CA3194410A1 - Stackable interlocking structural foam blocks for supporting stairs and other hardscape block systems - Google Patents

Abstract

Provided herein are various embodiments of stackable interlocking support blocks formed of rigid foam, for forming multi-course support systems for assembling hardscape stairs, and stair systems including such multi-course support systems and multiple concrete step blocks and/or concrete landing blocks supported thereby.

Description

STACKABLE INTERLOCKING STRUCTURAL FOAM BLOCKS FOR SUPPORTING
STAIRS AND OTHER HARDSCAPE BLOCK SYSTEMS
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to United States Provisional Patent Application Serial No.
63/412,810 entitled "EXTERIOR LANDSCAPE STAIRS STRUCTURAL FRAMEWORK USING
HIGH DENSITY STYROFOAM" filed on October 3, 2022.
FIELD OF THE INVENTION

[0002] The present disclosure relates generally to hardscape construction, and more particularly to techniques and systems useful for constructing stairs and other hardscape block systems from modular precast concrete blocks, copings and panels.
BACKGROUND OF THE INVENTION

[0003] For many years, landscape contractors have constructed outdoor steps to provide pedestrian access to buildings, raised patios, or any outdoor landscape that involves significant changes in grade.

[0004] While various techniques for constructing outdoor steps are known, including uses of hardscape blocks, improvements are desirable.
SUMMARY OF THE INVENTION

[0005] In accordance with an aspect, there is provided a stackable interlocking support block, the interlocking support block comprising: a rigid foam body comprising: a top side and a bottom side opposite the top side; a front side and a rear side opposite the front side;
and a first side and a second side opposite the first side; a vertical interlock system integral with the rigid foam body and comprising:
a top side interlocking structure associated with the top side and comprising, between the front side and the rear side, a first plurality of parallel ridges each having a front-rear depth of Wk and extending between the first side and the second side, each of the first plurality of parallel ridges spaced from each other by a gap having a front-rear depth of Wg, wherein a front edge of a frontmost of the parallel ridges of the first plurality of parallel ridges is spaced from the front side by a front-rear depth of 51 = k*Wk + (k-0.5)*Wg and a rear edge of the rearmost of the parallel ridges of the first plurality of parallel ridges is spaced from the rear side by a front-rear depth of S2 = (1+0.5)*Wk + l*Wg, wherein k and 1 are each integers greater than 0; a bottom side interlocking structure associated with the bottom side and comprising, between the front side and the rear side, a second plurality of parallel ridges each having the front-rear depth of Wk and extending between the first side and the second side, each of the second plurality of parallel ridges spaced from each other by a gap having the front-rear depth of Wg, wherein a front edge of a frontmost of the parallel ridges of the second plurality of parallel ridges is spaced from the front side by a front-rear depth of S3 = (m+0.5)*Wk + m*Wg and a rear edge of the rearmost of the Date Recue/Date Received 2023-03-28 parallel ridges of the second plurality of parallel ridges is spaced from the rear side by a front-rear depth of S4 = n*Wk + (n-0.5)*Wg, wherein m and n are each integers greater than 0;
and a horizontal interlock system integral with the rigid foam body and comprising: an overhang-type lateral interlock interface associated with the front side and having a front-rear depth of N; and an underhang-type lateral interlock interface associated with the rear side and having a front-rear depth of at least N.

[0006] In an embodiment, k and 1 are equal.

[0007] In an embodiment, m and n are equal.

[0008] In an embodiment, k and m are equal.

[0009] In an embodiment, 1 and n are equal.

[0010] In an embodiment, k = 1= m = n.

[0011] In an embodiment, k = 1= m = n = 1.

[0012] In an embodiment, at least one of k, 1, m, and n is different from the others.

[0013] In an embodiment, each of the ridges and the gaps has sloped walls.

[0014] In an embodiment, a distance Yt between midpoints of adjacent ridges is a nonzero integer multiple of 25 millimetres (mm).

[0015] In an embodiment, N = p * (0.5*Wk + 0.5*Wg), wherein p is an integer greater than 0.

[0016] In an embodiment, the overhang-type lateral interlock interface comprises: a first planar surface extending from a first end at the front side upwardly and rearwardly to a second end; and a second planar surface extending vertically downwardly from the second end to the bottom side; and the underhang-type lateral interlock interface comprises: a third planar surface extending from a third end at the rear side downwardly and frontwardly to a fourth end, the third planar surface being parallel to the first planar surface; and a fourth planar surface extending vertically upwardly from the fourth end to the top side.

[0017] In an embodiment, the first planar surface and the third planar surface have the same length.

[0018] In an embodiment, a distance between the top side and the first end equals the distance between the bottom side and the third end.

[0019] In an embodiment, each gap of the top side interlocking structure has a uniform top-bottom height that is equal to or greater than a top-bottom height of the ridges of the bottom side interlocking structure.

[0020] In an embodiment, each gap of the top side interlocking structure has a non-uniform top-bottom height that is no less than a top-bottom height of the ridges of the bottom-side interlocking structure.

[0021] In an embodiment, each gap of the top side interlocking structure has a sloped floor.

[0022] In an embodiment, the sloped floor slopes downwards from a point that is intermediate the first and second sides towards each of the first and second sides.

[0023] In accordance with an aspect, there is provided a multi-course support system for assembling hardscape stairs, the multi-course support system comprising a first course comprising a plurality of the stackable interlocking support blocks horizontally interlocked with each other; at least a second course Date Recue/Date Received 2023-03-28 comprising a plurality of the stackable interlocking support block horizontally interlocked with each other and stacked atop and vertically interlocked with adjacent ones of the stackable interlocking support blocks of the first course in a stepped configuration.

[0024] In accordance with another aspect, there is provided a stair system comprising: the multi-course support system; and a plurality of concrete step blocks and/or concrete landing blocks supported by the multi-course support system.

[0025] Various embodiments are described.
BRIEF DESCRIPTION OF THE FIGURES

[0026] Embodiments will now be described more fully with reference to the accompany drawings, in which:

[0027] FIG. 1 is a front perspective view of a set of steps, or stairs, formed using stacked hardscape blocks against a dwelling, in accordance with the prior art;

[0028] FIG. 2 is a front perspective view of a stage of the set of steps of FIG. 1 being constructed, in accordance with the prior art;

[0029] FIG. 3 is a front perspective view of another stage of the set of steps of FIG. 1 being constructed, in accordance with the prior art;

[0030] FIG. 4 is a front perspective view of another stage of the set of steps of FIG. 1 being constructed, in accordance with the prior art;

[0031] FIG. 5 is a side view of the set of steps of FIG. 1, with a hardscape block having been worked out of place over time to be off horizontal;

[0032] FIG. 6 is a front perspective view of the set of steps of FIG. 1 with several hardscape blocks having been worked out of place over time to be off horizontal, in accordance with the prior art;

[0033] FIG. 7 is a side view of the set of steps of FIG. 1 showing fill underlying the hardscape blocks and the pressures the fill imparts on the dwelling, in accordance with the prior art;

[0034] FIG. 8 is a side view of the set of steps of FIG. 1 showing fill becoming compacted over time resulting in instabilities and shifts which can cause the hardscape blocks overlying the fill to be worked out of place over time, in accordance with the prior art;

[0035] FIG. 9 is a rear perspective view of a stackable interlocking support block for a multi-course support system, according to an embodiment;

[0036] FIG. 10 is a first side elevation view of the support block of FIG. 9;

[0037] FIG. 11 is a side sectional view of a stair system incorporating a multi-course support system comprised of multiple of the stackable support blocks of FIG. 9, supporting concrete stair blocks;

[0038] FIG. 12 is an magnified side sectional view of a portion of the stair system of FIG. 11;

[0039] FIG. 13 is a side section view of a portion of an alternative stair system having a concrete stair block with a narrower step depth than that of FIG. 12;

Date Recue/Date Received 2023-03-28

[0040] FIG. 14 is a first side elevation view of multiple of the support blocks of FIG. 9 being stacked in a bond pattern;

[0041] FIG. 15 is a magnified first side elevation view of a portion of FIG.
14 with arrows representing the directions in which interblock movement is inhibited by both the vertical and horizontal interlock systems;

[0042] FIG. 16 is a side view of the stair system of FIG. 11 and a dwelling wall against which the stair system abuts, during a stage of its assembly using multiple of the stackable interlocking support block of FIG. 9 and concrete stair blocks supported thereby;

[0043] FIG. 17 is a first side view of the stackable interlocking support block of FIG. 9 showing a severing point of the support block for arrangement within the stair system of FIG. 16 during assembly;

[0044] FIG. 18 is a side view of the stair system of FIG. 11 and a dwelling wall against which the stair system abuts, during another stage of its assembly;

[0045] FIG. 19 is a side view of the stair system of FIG. 11 and a dwelling wall against which the stair system abuts, during another stage of its assembly;

[0046] FIG. 20 is a magnified first side view of the stackable interlocking support block of FIG. 9 showing height and width of the ridges, as well as sloped walls of the ridges and the gaps separating the ridges;

[0047] FIG. 21 is a side sectional view of an alternative stair system incorporating an alternative multi-course support system comprises of multiple of the stackable support blocks of FIG. 9, supporting concrete stair blocks and landing features;

[0048] FIG. 22 is a side view of a site being prepared for installation of a stair system;

[0049] FIG. 23 is a side view of a stage of assembly of the stair system at the site prepared as in FIG.
22;

[0050] FIG. 24 is a simplified front perspective view of placement of one of the stackable support blocks of FIG. 9 of a first course, with respect to a wall at the site of FIG.
22;

[0051] FIG. 25 is a side view of another stage of assembly of the stair system at the site prepared as in FIG. 22, with a simplified depiction of the stackable support blocks;

[0052] FIG. 26 is a simplified front perspective view of placement of several of the stackable support blocks of FIG. 9 of the first course, with respect to the wall at the site of FIG. 22;

[0053] FIG. 27 is a side view of another stage of assembly of the stair system at the site prepared as in FIG. 22, with a simplified depiction of the stackable support blocks;

[0054] FIG. 28 is a simplified front perspective view of placement of several of the stackable support blocks of FIG. 9 of the first course and one of a second course, with respect to the wall at the site of FIG. 22;

[0055] FIG. 29 is a simplified front perspective view of placement of several of the stackable support blocks of FIG. 9 of the first course and several of the second course, with respect to the wall at the site of FIG. 22;

Date Recue/Date Received 2023-03-28

[0056] FIG. 30 is a simplified front perspective view of placement of several of the stackable support blocks of FIG. 9 of the first course and several more of the second course, with respect to the wall at the site of FIG. 22;

[0057] FIG. 31 is a simplified front perspective view of placement of several of the stackable support blocks of FIG. 9 of the first course and several more of the second course, with respect to the wall at the site of FIG. 22, the stackable support blocks also supporting one level of stacked concrete blocks for forming one step/landing feature of the stair system;

[0058] FIG. 32 is a simplified front perspective view of placement of several of the stackable support blocks of FIG. 9 of the first course, several more of the second course, and two of a third course, with respect to the wall at the site of FIG. 22, the stackable support blocks also supporting two levels of stacked concrete blocks for forming two step/landing features of the stair system;

[0059] FIG. 33 is a simplified front perspective view of placement of several of the stackable support blocks of FIG. 9 of the first course, several more of the second course, and two of a third course, with respect to the wall at the site of FIG. 22, the stackable support blocks also supporting three levels of stacked concrete blocks for forming three step/landing features of the stair system;

[0060] FIG. 34 is a simplified front perspective view of a fully assembled stair system resulting from the progressive placement and stacking of several of the stackable support blocks of FIG. 9 to support placement and stacking of concrete blocks as depicted from FIGS. 22 to 32, and additional hardscape features including interlocking bricks/stones for forming a top landing and a bottom patio feature;

[0061] FIG. 35 is a front view of an alternative stackable support block having gaps with non-uniform top-bottom height for supporting the movement of fluid to the sides of the alternative stackable support block;

[0062] FIG. 36 is a magnified first side view of a portion of the alternative stackable support block of FIG. 35;

[0063] FIG. 37 is a magnified first side elevation view of portions of the support blocks of FIG. 9 interlocking horizontally and vertically in a bond pattern, and showing dimensions of potential alternative configurations of top side interlocking structures;

[0064] FIGS. 38 to 42 are magnified first side elevation views of portions of alternative support blocks with respective alternative configurations of top side interlocking structures;

[0065] FIG. 43 is a magnified first side elevation view of portions of the support blocks of FIG. 9 interlocking horizontally and vertically in a bond pattern, and showing dimensions of potential alternative configurations of bottom side interlocking structures; and

[0066] FIGS. 44 to 47 are magnified first side elevation views of portions of the support blocks of FIG.
36 with respective alternative configurations of bottom side interlocking structures.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Date Recue/Date Received 2023-03-28

[0067] The present application is directed to stackable interlocking support blocks formed of rigid foam, such as an expanded polystyrene (EPS) product, a polyisocyanurate product, and/or an extruded polystyrene (XPS) product, for forming multi-course support systems for assembling hardscape stairs, and to stair systems including such multi-course support systems and multiple concrete step blocks and/or concrete landing blocks supported thereby.

[0068] As disclosed above, for many years, landscape contractors have constructed outdoor steps to provide pedestrian access to buildings, raised patios, or any outdoor landscape that involves significant changes in grade. While steps can be constructed of wood, steel, or other materials, one common method is to use precast concrete retaining wall blocks or natural stone blocks to create the general form of the steps, and either coping units (caps) or specialized step units to act as treads for the steps.

[0069] FIG. 1 is a front perspective view of a set S of steps, or stairs, formed using stacked hardscape blocks against a dwelling, in accordance with the prior art. To construct set S of steps, a contractor forms a three-sided box against the dwelling wall (outside wall of a home, for example, underneath a doorway), with the units being stacked on either side of the steps to create sidewalls, and the cap units or step units placed between them to serve as treads. FIG. 2 is a front perspective view of a stage of the set S of steps of FIG. 1 being constructed with blocks B (referring generally to the concrete or stone blocks in FIG. 2), in accordance with the prior art. These are placed atop a large pad, typically of gravel, as the first course. FIG. 3 is a front perspective view of another stage of the set S of steps of FIG. 1 being constructed, in accordance with the prior art, and FIG. 4 is a front perspective view of yet another stage of the set S of steps of FIG. 1 being constructed, in accordance with the prior art. As the second and third courses are placed, including coping units and/or step units to form the treads, the interior of the structure is filled with gravel G and compacted. The process continues with stacking of the wall units to form the sidewalls, filling the inside with gravel and compacting, and progressively placing the step units course after course to form the stairs until the desired height is reached.

[0070] While this method of construction of sets of steps is common, there are drawbacks which can result in in poor performance of the construction over the long term. One drawback is that there is a lack of compaction of the gravel infill material within/supporting the steps.
Compaction of the gravel infill material is critical to long term performance of the set of steps.
Without good compaction, the step treads tend to settle and move over time due to repeated loading at the front of the step from pedestrian traffic. In the case of constructing a retaining wall, in contrast to constructing steps, the area behind the retaining wall blocks is large and open. This large open area enables a contractor to use sufficiently sized compaction equipment, such as a walk-behind diesel plate compactor or the like, to sufficiently compact gravel. However, in the case of step construction, the interior space is typically very small and constrained, particularly as the steps go higher. In many cases, a contractor is not able to use sufficiently-sized compaction equipment, such as a plate compactor, within this area. As a result, smaller, less effective equipment and methods are used, such as manual tamping. However, as a result Date Recue/Date Received 2023-03-28 of the space constraints limiting how effective gravel compaction can be done, the necessary gravel compaction is often not achieved.

[0071] When necessary gravel compaction is not achieved, repeated impact loads on the front edge of a step, causes the treads to be pounded down into the somewhat uncompacted gravel infill, causing the step to tilt forward over time. Depending on where the main path of use is on the steps, tread units can settle unevenly side to side as well as front to back. The settling can creates an unsafe and unattractive structure. FIG. 5 is a side view of the set S of steps of FIG. 1, with a hardscape block having been worked out of place over time to be off horizontal, in accordance with the prior art. FIG. 6 is a front perspective view of the set S of steps of FIG. 1 with several hardscape blocks having been worked out of place over time to be off horizontal, in accordance with the prior art.

[0072] Another major challenge when constructing exterior steps against an existing structure, such as a dwelling, is the lateral and vertical load the steps and the underlying gravel impart onto the structure.
With the method of step construction described above, a contractor can be piling tons of gravel against an existing structure, resulting in significant lateral loads. FIG. 7 is a side view of the set S of steps of FIG. 1 showing fill G underlying the hardscape blocks and the pressures the fill G and the weight of the overlying blocks themselves impart on the dwelling, in accordance with the prior art.

[0073] While basement walls may be designed for earth pressures, above grade walls may not have been designed with withstand such loads. Furthermore, in most typical residential construction, the soil/fill that is backfilled around the basement walls of the house or structure is not well engineered and is very often susceptible to settlement over time. In the case of traditional outdoor step construction, or other types of landscape construction that raises the grade such as a raised patio, the additional vertical load that is applied by the tons of gravel fill is significant and can also lead to significant settlement.
FIG. 8 is a side view of the set S of steps of FIG. 1 showing fill becoming compacted over time resulting in instabilities and shifts which can cause the hardscape blocks overlying the fill to be worked out of place over time, in accordance with the prior art.

[0074] It is an object of an aspect of this description to obviate or mitigate one or more of the above-described disadvantages of step construction.

[0075] In the present description, particular configurations of stackable interlocking support blocks formed of rigid foam and having density and size sufficient to support multiple courses of concrete or stone block, steps and other hardscape components, are described and shown in interaction to form a multi-course support system for constructing hardscape stairs.

[0076] FIG. 9 is a rear perspective view of a stackable interlocking support block 10 for a multi-course support system, according to an embodiment. FIG. 10 is a first side elevation view of support block 10. In this embodiment, support block 10 includes a rigid foam body having a top side 12 and a bottom side 14 opposite top side 12, a front side 16 and a rear side 18 opposite front side 16, and a first side 20 and a second side 22 opposite first side 20. In this embodiment, the rigid foam body is formed of high density expanded polystyrene (EPS), cut or molded with the features described herein. It will be Date Recue/Date Received 2023-03-28 appreciated that support block 10, which may be referred to as an EPS
Framework, or EPSF, may be used with other like blocks in various configurations to construct hardscape stairs or may be used in other applications such as for raised patios or elevated walkways. In the present description, applications in the construction of stairs will be explained in particular detail.

[0077] Support block 10 includes a vertical interlock system that is integral with the rigid foam body.
As will be described, the vertical interlock system enables support block 10 to vertically interlock with like support blocks 10 on adjacent courses of a multi-course support system.
The relative dimensions of features of the vertical interlock system are provided to enable support block 10 to be stacked in various bond patterns, offset to accommodate the placement and support of concrete and/or stone hardscape components as will be described.

[0078] In this embodiment, the vertical interlock system includes a top side interlocking structure 120 associated with top side 12. The top side interlocking structure includes, between front side 16 and rear side 18, a first plurality of parallel ridges 122 (or ribs) each having a front-rear depth of Wk and extending between first side 20 and second side 22. The first plurality of parallel ridges 122 both provide interlocking functions and support functions for supporting a stone/concrete block. Each of the first plurality of parallel ridges 122 is spaced from each other by a gap 124 that has a front-rear depth of Wg. In this embodiment, a front edge of a frontmost of the parallel ridges of the first plurality of parallel ridges (the leftmost of ridges 122 in FIG. 10) is spaced from front side 16 by a front-rear depth of Wk + 0.5*Wg. Furthermore, a rear edge of the rearmost of the parallel ridges of the first plurality of parallel ridges 124 (the rightmost of ridges 122 in FIG. 10) is spaced from rear side 18 by a front-rear depth of 1.5*Wk + Wg. These relative dimensions are also shown in FIG. 15, below.

[0079] The vertical interlock system of support block 10 also includes a bottom side interlocking structure associated with bottom side 14. The bottom side interlocking structure includes, between front side 16 and rear side 18, a second plurality of parallel ridges 142 (or ribs) each having the front-rear depth of Wk and extending between first side 20 and second side 22. Each of the second plurality of parallel ridges is spaced from each other by a gap 144 having the front-rear depth of Wg. In this embodiment, a front edge of a frontmost of the parallel ridges 142 of the second plurality of parallel ridges (the leftmost of ridges 142 in FIG. 10) is spaced from front side 16 by a front-rear depth of 1.5 *Wk + Wg. Furthermore, a rear edge of the rearmost of the parallel ridges 142 of the second plurality of parallel ridges is spaced from rear side 18 by a front-rear depth of Wk +
0.5*Wg. It will be appreciated that front side 16 is the maximum extent of support block 10 to the left (in FIG. 10) and rear side 18 is the maximum extent of support block 10 to the right (in FIG.
10). These relative dimensions are also shown in FIG. 15, below.

[0080] In this embodiment, each of the ridges 124, 144 and gaps 122, 142 has sloped walls useful for easing interlocking during stair construction of and reducing interactions between sharp edges.

[0081] Support block 10 also includes a horizontal interlock system integral with the rigid foam body.
In this embodiment, the horizontal interlock system includes an overhang-type lateral interlock interface Date Recue/Date Received 2023-03-28 160 associated with front side 16 and having a front-rear depth of N, and an underhang-type lateral interlock interface 180 associated with rear side 18 and having a front-rear depth of at least N. In this embodiment, N is equal to 0.5Wk + 0.5Wg. However, N may be larger than this, and in general may be p * (0.5Wk + 0.5Wg), where p is an integer greater than 0.

[0082] In this embodiment, overhang-type lateral interlock interface 160 includes a first planar surface 162 extending from a first end at front side 16 upwardly and rearwardly to a second end, and a second planar surface 164 extending vertically downward from the second end to bottom side 14. Also, underhang-type lateral interlock interface 180 includes a third planar surface 182 extending from a third end at rear side 18 downwardly and frontwardly to a fourth end, and a fourth planar surface extending vertically upwardly from the fourth end to top side 12. In this embodiment, first planar surface 162 and third planar surface 182 have the same length, and a distance between top side 12 and the first end equals the distance between bottom side 14 and the third end. These aspects are also shown in FIG. 15.

[0083] It will be appreciated that, because support block 10 is formed of a rigid foam body, it is lightweight and easy to manipulate for stacking and interlocking when forming stairs. Its light weight compared with gravel fill is very useful for reducing pressure against a dwelling wall, and its rigidity is very useful because it is not as subject to compaction over time as is only lightly-compacted gravel.
However, the lightness of support block 10 also makes it subject to jarring and being shifted out of place when being stepped around, backfilled around, and the like during actual construction. As such, the horizontal interlock system and the vertical interlock system are very useful for inhibiting shifting of a support block out of its initial place relative to an adjacent support block with which it is horizontally interlocked during construction, easing the process of construction and reducing opportunities for frustration.

[0084] Support block 10 is usable as a multi-course support system for a stair system constructed using the multi-course system to support precast concrete, natural stone, or other type of cladding system ("the cladding"). Such cladding is typically modular and acts as the protective shield and to provide the aesthetics for the structure. Examples of this type of cladding include a precast concrete retaining wall system, concrete pavers for landing areas, natural stone blocks and/or pavers, etc. Support block is configured to perform several functions during and after the step/fill construction, and to solve many of the problems discussed above in connection with prior art systems.

[0085] FIG. 35 is a front view of an alternative stackable support block having gaps with non-uniform top-bottom height for supporting the movement of fluid to the sides of the alternative stackable support block;

[0086] FIG. 36 is a magnified first side view of a portion of the alternative stackable support block of FIG. 35;

[0087] FIG. 36 is a magnified first side elevation view of portions of the support blocks of FIG. 9 interlocking horizontally and vertically in a bond pattern, and showing dimensions of potential alternative configurations of top side interlocking structures;

Date Recue/Date Received 2023-03-28

[0088] FIGS. 37 to 41 are magnified first side elevation views of portions of the support blocks of FIG.
36 with respective alternative configurations of top side interlocking structures;

[0089] FIG. 42 is a magnified first side elevation view of portions of the support blocks of FIG. 9 interlocking horizontally and vertically in a bond pattern, and showing dimensions of potential alternative configurations of bottom side interlocking structures; and

[0090] FIGS. 43 to 46 are magnified first side elevation views of portions of the support blocks of FIG.
36 with respective alternative configurations of bottom side interlocking structures.

[0091] Support block 10 is continuous throughout its width to enable 2D
cutting with common hot-wire or CNC cutting machines. Furthermore, the support block height H is dimensioned to match the step rise and cladding unit height. It will be appreciated that typical step risers range between 150mm-200mm, depending on building code requirements.

[0092] FIG. 11 is a side sectional view of a stair system SS incorporating a multi-course support system comprised of multiple of the support blocks 10, and supporting concrete stair blocks C, B. In particular, in this embodiment a segmental retaining wall (SRW) block B and a coping or cap unit C are set directly on the front of the ridged (ribbed) surface of an underlying support block 10.
It will be noted that the depth of support block 10 is, in this embodiment, more than twice the depth of the step (the tread depth) to enable a bond pattern with the support blocks 10 in an adjacent course above it. The SRW block height is equal to the height H of the support blocks 10.

[0093] FIG. 12 is a magnified side sectional view of a portion of the stair system SS. The location of the interlocking ridges is related of the depth of the chosen SRW or cladding system. Again, in the case of landscape steps as in this embodiment, this depth is commonly known as tread depth. While relationships between aspects of the ridges 122, 144 and gaps 124, 144 on top side 12 and bottom side 14 have been described above, it may also be observed that in this embodiment the location of the first gap 144 on bottom side 14 relative to the first ridge 122 on top side 12 is X1 = N + D + Wk + 0.5*Wg, where D is the maximum possible tread depth of the SRW block or cladding unit, Wk is the width of the ridges 122/142 and Wg is the width of the grooves 124, 144. Accordingly, with uniform ridge widths and gap widths, subsequent ridges 122/142 are spaced equally apart a distance Yt. Yt is established to accommodate the typical incremental depths of the system and provide for sufficient interlock between units. It is typical for tread depths to be provided in increments of 25mm, such as 250mm, 275mm, 300mm, and so forth.

[0094] FIG. 13 is a side section view of a portion of an alternative stair system SSam having a concrete block B coping C providing a narrower step depth than that D of stair system SS in FIG. 12. That is, in relation to that of stair system SS, with stair system SSam, tread depth is reduced by using an SRW
block that is D ¨ 2 (Yt), where Yt is the incremental offset/spacing of the teeth. As indicated above, a typical increment in SRW Systems is 25mm, so in this example, by moving support block 10 forward by 2 ridges 124, there is accommodated a 250mm tread depth instead of the 300mm tread depth of stair system SS.
Date Recue/Date Received 2023-03-28

[0095] To continue to create a structural fill volume using the multi-course support system, additional support blocks 10 are stacked and both horizontally and vertically interlocked in a bond pattern to fill the entire volume. FIG. 14 is a first side elevation view of multiple of the support blocks of FIG. 9 being stacked in a bond pattern. To ensure continuity of ridges over the entire depth of the fill area, the ridges must continually line up as they are joined front to back. Xf represents a distance between rear side 18 of a leftmost support block 10 and the centre of a first ridge 142 to enable that first ridge 142 to align with a corresponding gap in an adjacent support block 10 in the course below. It will be appreciated that Ro represents the centre-to-centre distance of gaps 124, 144.

[0096] When adjacent support blocks 10 are interlocked both horizontally and vertically, the units are secured in two directions. FIG. 15 is a magnified first side elevation view of a portion of FIG. 14 with arrows representing the directions in which interblock movement is inhibited by both the vertical and horizontal interlock systems. FIG. 15 also shows and explains a number of the interrelated features referred to above.

[0097] In the situation of a stair system, support blocks 10 are often abutting an existing structure, such as a dwelling. As such, support blocks 10 are configured to be cut to various sizes to fit and be re-used in the multi-course support structure. FIG. 16 is a side view of stair system SS and a dwelling wall against which stair system SS abuts, during a stage of its assembly using multiple of the stackable interlocking support block of FIG. 9 and concrete stair blocks (C, B, for examples) supported thereby.
As shown in FIG. 16, a bottom course requires exactly 3 support blocks 10 to complete a base. On the next course, the support blocks 10 are offset a distance equal to the tread depth (TD). As such, the last support block 10 (the one closest to the wall), is cut to fit, where the cut piece would have a length Q
equaling the difference between the total depth D of support block 10 and TD.
Therefore, Q = D ¨ TD.
FIG. 17 is a first side view of the stackable interlocking support block 10 showing a severing point V
for arrangement within the stair system SS during assembly.

[0098] FIG. 18 is a side view of stair system SS and a dwelling wall against which the stair system abuts, during another stage of its assembly, and FIG. 19 is a side view of stair system SS during another stage of its assembly. To enable the cut-off piece of the support block 10 (the piece left over after Q) to be reused on the next course, it may be rotated/flipped front-rear so as to turn the underhang-type horizontal interlock interface 180 to serve thereafter as an overhang-type horizontal interlock interface 160. By having the interlocking ridges 122, 142 and gaps 124, 144 on both top side 12 and bottom side 14, support block 10 may be made compatible with other like support blocks on different courses and on the same course.

[0099] In this embodiment, ribs 122, 142 are dimensioned and positioned balance the need for stable interlock against a capacity to support the vertical load of concrete/stone cladding on the multi-source support structure of which it is a part. FIG. 20 is a magnified first side view of support block 10 showing height Rh and width Rw of ridges 122, as well as sloped walls Ra of ridges 122 and of gaps 124 separating ridges 122. To reduce the applied pressure on a ridge 122 from a load such as a wall block Date Recue/Date Received 2023-03-28 or cladding with live loads), the width Rw of ridges should be sufficiently large, while taking into consideration the need to make the offset increment Yt as minimal as possible to adapt to various tread depths. A further constraint is the sloping edges of the ridges 122 (Ra), which are useful for helping guide support blocks 10 from above into place. To maximize the width Rw of ridges 122/142 and therefore maximize the bearing capacity of support blocks 10, it was determined that the height of the ridges Rh should be as small as possible without compromising the interlocking ability. It was found that an approximate Rw to Rh ratio of 4:1 provided a useful balance taking into account the factors explained above.

[0100] Due to the relative dimensions of support block 10, it may be stacked with other like blocks to accommodate various configurations of stair systems. For example, support blocks 10 may be stacked to be set back further than an SRW depth or cladding depth a landing or a wider step area is desired.

[0101] FIG. 21 is a side sectional view of an alternative stair system SSalt2 incorporating an alternative multi-course support system comprised of multiple support blocks 10, supporting concrete stair blocks C/B and landing features Ul and U2. As shown in FIG. 21, a gravel infill material can in fact be used to fill zones between support blocks 10 and support pavers in these U1/U2 regions.

[0102] Support block 10 can perform several functions during and after the step construction. Stages of step construction for forming stair system SSa1t2 are hereafter explained in relation to FIGS. 22 to 34.

[0103] FIG. 22 is a side view of a site being prepared for installation of stair system SSa1t2. A base excavation is typically the first step in the stair system construction process. Typically, soil would be excavated to a depth of 300mm or more below the proposed bottom step grade, or as required to reach competent subgrade, shown as Wd. The width of the excavation would typically be the required step width plus an additional 150-200mm around the perimeter to allow the gravel base to extend beyond the limits of the structure. A gravel base with a minimum 150-200mm thickness would typically be compacted to the required density.

[0104] FIG. 23 is a side view of a stage of assembly of stair system SSa1t2.
In particular, if required to ease the levelling process, a base course (a layer of concrete base units) can be set down to create a level area that would evenly support the support blocks 10 and concrete sidewalls.

[0105] FIG. 24 is a simplified front perspective view of placement of one of the support blocks 10 of a first course, with respect to a wall. This first support block 10 would be placed the required distance out from the abutting structure based on the overall step dimensions.

[0106] FIG. 25 is a side view of another stage of assembly of stair system SSa1t2, with a simplified depiction of the support blocks 10 (in particular, only some ridges 122 of support blocks 10 are shown) and showing additional support blocks 10 interlocked horizontally behind the first support block 10 towards the wall. FIG. 26 is a simplified front perspective view of placement of several support blocks of the first course, with respect to the wall.

[0107] FIG. 27 is a side view of another stage of assembly of stair system SSa1t2, and FIG. 28 is a simplified front perspective view of placement of several support blocks 10 of the first course and one Date Recue/Date Received 2023-03-28 of a second course. This next course of support blocks 10 are offset a distance equal to the block/tread depth as.

[0108] FIG. 29 is a simplified front perspective view of placement of several support blocks 10 of the first course and several of the second course, and FIG. 30 is a simplified front perspective view of placement of several support blocks 10 of the first course and several more of the second course.
Adjacent units are thus interlocked as shown, to fill the subsequent course.
If a depth to be filled is not a multiple of the depth of a support block 10, a support block 10 can be easily cut to fit, using for example a hot-knife/wire, a utility knife, or some other tool.

[0109] FIG. 31 is a simplified front perspective view of placement of several support blocks 10 of the first course and several more of the second course. The support blocks 10 also supporting one level of stacked concrete blocks C/B for forming one step/landing feature of stair system SSa1t2. The first row of blocks and coping units (treads) are placed directly on top of the first row of SRW or cladding blocks.

[0110] FIG. 32 is a simplified front perspective view of placement of several support blocks 10 of the first course, several more of the second course, and two of a third course, the support blocks 10 also supporting two levels of stacked concrete blocks C for forming two step/landing features of stair system SSa1t2. The second course of support blocks 10 are thus placed, with the offset relative to the support blocks 10 below equalling the tread depth.
101111 It will be appreciated with reference to the above that a support block 10 acts as a both a form and a guide for the rest of the step construction. In contrast to prior art landscape step construction, where an installer would attempt to both compact and level the gravel infill material in this very tight space (i.e. typically too tight for a vibratory compactor), the multi-course support system made of multiple support blocks 10 provides a level bearing surface, a low-compressibility bearing surface within the specified load constraints, and a horizontal guide for placement of concrete blocks and other hardscape components. Therefore, due to its lightness, physical shape, and configuration, support block can be used to replaces three (3) important tasks that an installer contractor is expected to achieve within a very tight space. That is, levelling each step with compacted gravel is a time-consuming task and, if not done correctly, will result in uneven steps and potential trip hazards in time. Furthermore, compaction of this levelling course is equally as difficult given the tight space constraints. Inadequate compaction using traditional step building methods tends to result in settlement over time, poor aesthetics, and potential hazards for pedestrians. Also, using the front side 16 of a support block 16 as a horizontal guide, the need for string lines and other alignment tools is reduced or eliminated. As such, it will be appreciated that the support block 10, and multi-course support systems made therefrom, saves considerable time, resources, and energy during the construction of steps, and additionally provides long term benefits in the performance of the steps over their life.
[0112] FIG. 33 is a simplified front perspective view of placement of several support blocks 10 of the first course, several more of the second course, and two of a third course, with respect to the wall, the stackable support blocks also supporting three levels of stacked concrete blocks for forming three Date Recue/Date Received 2023-03-28 step/landing features of stair system SSa1t2. In this stair system, this represents the last course of blocks/coping units.
[0113] FIG. 34 is a simplified front perspective view of fully assembled stair system SSalt2 resulting from the progressive placement and stacking of several support blocks 10 to support placement and stacking of blocks as depicted from FIGS. 22 to 32, and additional hardscape features including interlocking bricks/stones for forming a top landing and a bottom patio feature.
[0114] It should be observed that, with the support block 10, and multi-course support systems formed therefrom, there is little to no outward lateral pressure on stair sidewalls, since the support blocks 10 transfer all loads vertically to the foundation pad. This is yet another benefit; the support block 10 and multi-course support systems described herein structurally apply little to no lateral load to either step sidewalls or the foundation wall of a dwelling against which a stair system is being constructed.
[0115] While embodiments have been described, alternatives are possible.
[0116] For example, while embodiments of the stackable interlocking support block disclosed herein include a gap with a width Wg that is about equal to the width Wk of the ridges, gaps may have a width Wg that is an integer multiple of the width Wk of the ridges, such that a given gap may accommodate not just one ridge but two ridges with a gap in between. Alternatives are possible.
[0117] Furthermore, while embodiments of the stackable interlocking support block disclosed herein include gaps having a uniform top-bottom height that is at least the same or greater that the height of the ridges, so as to at least accommodate receiving the ridges from a like support block in an adjacent course, a non-uniform top-bottom height of the gaps is possible. Provided that the minimum top-bottom height is at least the same or greater than the height of the ridges, a maximum top-bottom height may be even greater than the minimum. FIG. 35 is a front side view of a stackable interlocking support block 200, according to an alternative embodiment. FIG. 36 is a first side view of the support block 200. Support block 200 is similar to support block 10 described herein. As shown, support block 200 includes a top side 212 and a bottom side 214 opposite top side 212, a front side 216 and a rear side 218 opposite front side 216, and a first side 220 and a second side 222 opposite first side 220. A vertical interlock system has a top side interlocking structure 230 associated with top side 212 and a bottom side interlocking structure 240 associated with bottom side 214. Top side interlocking structure 230 has a plurality of ridges 232 and gaps 234 between ridges 232. However, with support block 200, gaps 234 have non-uniform top-bottom heights, in particular sloping floors 236 that can guide moisture to first side 220 and second side 222 thereby to reduce the chance of moisture, such as from rainfall, remaining atop support block 200. As such, gaps 234 can function also as drainage channels. In this embodiment, the midpoint of the gaps between the first side 220 and the second side 222 have the highest elevation of floor 236, and the floor slopes downwards from the midpoint towards each of the first side 220 and the second side 222, in an inverted "V" shape. Alternatives are possible in which a highest elevation of floor 236 is not at the midpoint. For example, an alternative configuration of floor may enable a slope to run away from a dwelling against which a stair system is positioned thereby to Date Recue/Date Received 2023-03-28 channel moisture flow away from the dwelling. For mass manufacturing, formation of support block 220 with such drainage channels may be beneficially done entirely within a specialized mold, rather than first molding support block 220 and then cutting finer features with a hot wire or other post-molding shaping system.
[0118] Further, while embodiments have been shown in which the front edge of the frontmost ridge on the top side is spaced a distance Si = Wk + 0.5*Wg from the front side, a larger spacing from the front side to the front edge of the frontmost ridge on the top side is possible in alternative embodiments, provided the spacing enables the stacking of a like block on top with vertical interlock. To an extent, therefore, this spacing can be generalized such that the front edge of the frontmost ridge on the top side is spaced a distance of Si = k*Wk + (k-0.5)*Wg from the front side, where k is an integer greater than 0. Thus, the embodiments shown previously have k = 1, but if k = 2 or k = 3 or k is some other integer greater than 0, the correct spacing to enable course-on-course bonded interlock should continue.
[0119] FIG. 37 is a magnified first side elevation view of portions of support blocks 10 interlocking horizontally and vertically in a bond pattern, and showing dimensions of potential alternative configurations of top side interlocking structures. For example, k may be 1, 2, 3 or some other nonzero integer. It will be appreciated that if k is too great, however, support of an overlying step block by the support block or the ability to vertically interlock with a support block in an adjacent course may be impaired. Therefore, while k may indeed be an integer value greater than 1 if desired, there may be a limit to how great, in practice, k can actually be.
[0120] Similarly, while embodiments have been shown in which the rear edge of the rearmost ridge on the top side is spaced a distance S2 = 1.5*Wk + Wg from the rear side, a larger spacing from the rear side to the rear edge of the rearmost ridge on the top side is possible provided the spacing enables the stacking of a like block on top with vertical interlock. To an extent, therefore, this can be generalized such that the rear edge of the rearmost ridge on the top side is spaced a distance of S2 = (1+0.5)*Wk +
l*Wg from the rear side, where 1 is an integer greater than 0. Thus, the embodiments shown previously have 1 = 1, but if 1 = 2 or 1 = 3 or 1 is some other integer greater than 0, the correct spacing to enable course-on-course bonded interlock should continue. Different values of 1 are shown in FIG. 37. For example, 1 may be 1, 2, 3 or some other nonzero integer. It will be appreciated that if 1 is too great, however, support of an overlying step block by the support block or the ability to vertically interlock with a support block in an adjacent course may be impaired. Therefore, while 1 may indeed be an integer value greater than 1 if desired, there may be a limit to how great, in practice, 1 can actually be.
[0121] FIGS. 38 to 41 are magnified first side elevation views of portions of alternative support blocks 301, 302, 303, 304 with respective alternative configurations of top side interlocking structures. In support block 301, k = 2 and 1= 1. In support block 302, k = 2 and 1= 2. In support block 303, k = 1 and 1= 2. In support block 301, k = 1 and 1= 3. Alternatives are possible.
[0122] Similarly, while embodiments have been shown in which the front edge of the frontmost ridge on the bottom side is spaced a distance S3 = 1.5*Wk + Wg from the front side, a larger spacing from Date Recue/Date Received 2023-03-28 the front side to the front edge of the frontmost ridge on the bottom side is possible provided the spacing enables the block to be stacked on top of a like block with vertical interlock. To an extent, therefore, this can be generalized such that the front edge of the frontmost ridge on the bottom side is spaced a distance of S3 = (m+0.5)*Wk + m*Wg from the front side, where m is an integer greater than 0. Thus, the embodiments shown previously have m = 1, but if m = 2 or m = 3 or m is some other integer greater than 0, the correct spacing to enable course-on-course bonded interlock should continue.
[0123] FIG. 42 is a magnified first side elevation view of portions of support blocks 10 interlocking horizontally and vertically in a bond pattern, and showing dimensions of potential alternative configurations of bottom side interlocking structures. For example, m may be 1, 2, 3 or some other nonzero integer. It will be appreciated that if m is too great, however, stable placement atop the ground or placement atop and/or vertical interlock with another support block in an adjacent course may be impaired. Therefore, while m may indeed be an integer value greater than 1 if desired, there may be a limit to how great, in practice, m can actually be.
[0124] Similarly, while embodiments have been shown in which the rear edge of the rearmost ridge on the bottom side is spaced a distance S4 = Wk + 0.5Wg from the rear side, a larger spacing from the rear side to the rear edge of the rearmost ridge on the bottom side is possible provided the spacing enables the block to be stacked on top of a like block with vertical interlock. To an extent, therefore, this can be generalized such that the rear edge of the rearmost ridge on the bottom side is spaced a distance of S4 = n*Wk + (n-0.5)*Wg from the rear side, where n is an integer greater than 0. Thus, the embodiments shown previously have n = 1, but if n = 2 or n = 3 or n is some other integer greater than 0, the correct spacing to enable course-on-course bonded interlock should continue. Different values of n are shown in FIG. 42. For example, n may be 1, 2, 3 or some other nonzero integer. It will be appreciated that if n is too great, however, stable placement atop the ground or placement atop and/or vertical interlock with another support block in an adjacent course may be impaired. Therefore, while n may indeed be an integer value greater than 1 if desired, there may be a limit to how great, in practice, n can actually be.
[0125] FIGS. 43 to 46 are magnified first side elevation views of portions of alternative support blocks 305, 306, 307, 308 with respective alternative configurations of bottom side interlocking structures. In support block 305, m = 2 and n = 1. In support block 306, m = 2 and n = 2. In support block 307, m =
1 and n = 2. In support block 308, m = 1 and n = 3. Alternatives are possible.
[0126] Clauses [0127] Clause 1. A stackable interlocking support block, the interlocking support block comprising:
[0128] a rigid foam body comprising:
[0129] a top side and a bottom side opposite the top side;
[0130] a front side and a rear side opposite the front side; and [0131] a first side and a second side opposite the first side;
[0132] a vertical interlock system integral with the rigid foam body and comprising:

Date Recue/Date Received 2023-03-28 [0133] a top side interlocking structure associated with the top side and comprising, between the front side and the rear side, a first plurality of parallel ridges each having a front-rear depth of Wk and extending between the first side and the second side, each of the first plurality of parallel ridges spaced from each other by a gap having a front-rear depth of Wg, wherein a front edge of a frontmost of the parallel ridges of the first plurality of parallel ridges is spaced from the front side by a front-rear depth of Si = k*Wk + (k-0.5)*Wg and a rear edge of the rearmost of the parallel ridges of the first plurality of parallel ridges is spaced from the rear side by a front-rear depth of S2 =
(1+0.5)*Wk + l*Wg, wherein k and 1 are each integers [0134] a bottom side interlocking structure associated with the bottom side and comprising, between the front side and the rear side, a second plurality of parallel ridges each having the front-rear depth of Wk and extending between the first side and the second side, each of the second plurality of parallel ridges spaced from each other by a gap having the front-rear depth of Wg, wherein a front edge of a frontmost of the parallel ridges of the second plurality of parallel ridges is spaced from the front side by a front-rear depth of S3 = (m+0.5)*Wk + m*Wg and a rear edge of the rearmost of the parallel ridges of the second plurality of parallel ridges is spaced from the rear side by a front-rear depth of S4= n*Wk + (n-0.5)*Wg, wherein m and n are each integers greater than 0;
[0135] and [0136] a horizontal interlock system integral with the rigid foam body and comprising:
[0137] an overhang-type lateral interlock interface associated with the front side and having a front-rear depth of N; and [0138] an underhang-type lateral interlock interface associated with the rear side and having a front-rear depth of at least N.
[0139] Clause 2. The stackable interlocking support block of clause 1, wherein k and 1 are equal.
[0140] Clause 3. The stackable interlocking support block of clause 1, wherein m and n are equal.
[0141] Clause 4. The stackable interlocking support block of clause 1, wherein k and m are equal.
[0142] Clause 5. The stackable interlocking support block of clause 1, wherein 1 and n are equal.
[0143] Clause 6. The stackable interlocking support block of clause 1, wherein k = 1= m = n.
[0144] Clause 7. The stackable interlocking support block of clause 6, wherein k = 1= m = n = 1.
[0145] Clause 8. The stackable interlocking support block of clause 1, wherein at least one of k, 1, m, and n is different from the others.
[0146] Clause 9. The stackable interlocking support block of clause 1, wherein each of the ridges and the gaps has sloped walls.
[0147] Clause 10. The stackable interlocking support block of clause 1, wherein a distance Yt between midpoints of adjacent ridges is a nonzero integer multiple of 25 millimetres (mm).
[0148] Clause 11. The stackable interlocking support block of clause 1, wherein N = p * (0.5 *Wk +
0.5*Wg), wherein p is an integer greater than 0.

Date Recue/Date Received 2023-03-28 [0149] Clause 12. The stackable interlocking support block of clause 1, wherein the overhang-type lateral interlock interface comprises: a first planar surface extending from a first end at the front side upwardly and rearwardly to a second end; and a second planar surface extending vertically downwardly from the second end to the bottom side; and wherein the underhang-type lateral interlock interface comprises: a third planar surface extending from a third end at the rear side downwardly and frontwardly to a fourth end, the third planar surface being parallel to the first planar surface; and a fourth planar surface extending vertically upwardly from the fourth end to the top side.
[0150] Clause 13. The stackable interlocking support block of clause 10, wherein the first planar surface and the third planar surface have the same length.
[0151] Clause 14. The stackable interlocking support block of clause 10, wherein a distance between the top side and the first end equals the distance between the bottom side and the third end.
[0152] Clause 15. The stackable interlocking support block of clause 1, wherein each gap of the top side interlocking structure has a uniform top-bottom height that is equal to or greater than a top-bottom height of the ridges of the bottom side interlocking structure.
[0153] Clause 16. The stackable interlocking support block of clause 1, wherein each gap of the top side interlocking structure has a non-uniform top-bottom height that is no less than a top-bottom height of the ridges of the bottom-side interlocking structure.
[0154] Clause 17. The stackable interlocking support block of clause 14, wherein each gap of the top side interlocking structure has a sloped floor.
[0155] Clause 18. The stackable interlocking support block of clause 15, wherein the sloped floor slopes downwards from a point that is intermediate the first and second sides towards each of the first and second sides.
[0156] Clause 19. A multi-course support system for assembling hardscape stairs, the multi-course support system comprising: a first course comprising a plurality of the stackable interlocking support block of clause 1 horizontally interlocked with each other; at least a second course comprising a plurality of the stackable interlocking support block of clause 1 horizontally interlocked with each other and stacked atop and vertically interlocked with adjacent ones of the stackable interlocking support blocks of the first course in a stepped configuration.
[0157] Clause 20. A stair system comprising: the multi-course support system of clause 19; and a plurality of concrete step blocks and/or concrete landing blocks supported by the multi-course support system.

Date Recue/Date Received 2023-03-28

Claims (20)

WHAT IS CLAIMED IS:

1. A stackable interlocking support block, the interlocking support block comprising:
a rigid foam body comprising:
a top side and a bottom side opposite the top side;
a front side and a rear side opposite the front side; and a first side and a second side opposite the first side;
a vertical interlock system integral with the rigid foam body and comprising:
a top side interlocking structure associated with the top side and comprising, between the front side and the rear side, a first plurality of parallel ridges each having a front-rear depth of Wk and extending between the first side and the second side, each of the first plurality of parallel ridges spaced from each other by a gap having a front-rear depth of Wg, wherein a front edge of a frontmost of the parallel ridges of the first plurality of parallel ridges is spaced from the front side by a front-rear depth of S1 =
k*Wk + (k-0.5)*Wg and a rear edge of the rearmost of the parallel ridges of the first plurality of parallel ridges is spaced from the rear side by a front-rear depth of S2 =
(1+0.5)*Wk + l*Wg, wherein k and 1 are each integers greater than 0;
a bottom side interlocking structure associated with the bottom side and comprising, between the front side and the rear side, a second plurality of parallel ridges each having the front-rear depth of Wk and extending between the first side and the second side, each of the second plurality of parallel ridges spaced from each other by a gap having the front-rear depth of Wg, wherein a front edge of a frontmost of the parallel ridges of the second plurality of parallel ridges is spaced from the front side by a front-rear depth of S3 = (m+0.5)*Wk + m*Wg and a rear edge of the rearmost of the parallel ridges of the second plurality of parallel ridges is spaced from the rear side by a front-rear depth of S4 = n*Wk + (n-0.5)*Wg, wherein m and n are each integers greater than 0;
and a horizontal interlock system integral with the rigid foam body and comprising:
an overhang-type lateral interlock interface associated with the front side and having a front-rear depth of N; and an underhang-type lateral interlock interface associated with the rear side and having a front-rear depth of at least N.

2. The stackable interlocking support block of claim 1, wherein k and 1 are equal.

3. The stackable interlocking support block of claim 1, wherein m and n are equal.

4. The stackable interlocking support block of claim 1, wherein k and m are equal.

5. The stackable interlocking support block of claim 1, wherein 1 and n are equal.

6. The stackable interlocking support block of claim 1, wherein k =1= m =
n.

7. The stackable interlocking support block of claim 6, wherein k =1= m = n = 1.

8. The stackable interlocking support block of claim 1, wherein at least one of k, 1, m, and n is different from the others.

9. The stackable interlocking support block of claim 1, wherein each of the ridges and the gaps has sloped walls.

10. The stackable interlocking support block of claim 1, wherein a distance Yt between midpoints of adjacent ridges is a nonzero integer multiple of 25 millimetres (mm).

11. The stackable interlocking support block of claim 1, wherein N = p *
(0.5*Wk + 0.5*Wg), wherein p is an integer greater than 0.

12. The stackable interlocking support block of claim 1, wherein the overhang-type lateral interlock interface comprises:
a first planar surface extending from a first end at the front side upwardly and rearwardly to a second end; and a second planar surface extending vertically downwardly from the second end to the bottom side;
and wherein the underhang-type lateral interlock interface comprises:
a third planar surface extending from a third end at the rear side downwardly and frontwardly to a fourth end, the third planar surface being parallel to the first planar surface; and a fourth planar surface extending vertically upwardly from the fourth end to the top side.

13. The stackable interlocking support block of claim 10, wherein the first planar surface and the third planar surface have the same length.

14. The stackable interlocking support block of claim 10, wherein a distance between the top side and the first end equals the distance between the bottom side and the third end.

15. The stackable interlocking support block of claim 1, wherein each gap of the top side interlocking structure has a uniform top-bottom height that is equal to or greater than a top-bottom height of the ridges of the bottom side interlocking structure.

16. The stackable interlocking support block of claim 1, wherein each gap of the top side interlocking structure has a non-uniform top-bottom height that is no less than a top-bottom height of the ridges of the bottom-side interlocking structure.

17. The stackable interlocking support block of claim 14, wherein each gap of the top side interlocking structure has a sloped floor.

18. The stackable interlocking support block of claim 15, wherein the sloped floor slopes downwards from a point that is intermediate the first and second sides towards each of the first and second sides.

19. A multi-course support system for assembling hardscape stairs, the multi-course support system comprising:
a first course comprising a plurality of the stackable interlocking support block of claim 1 horizontally interlocked with each other;
at least a second course comprising a plurality of the stackable interlocking support block of claim 1 horizontally interlocked with each other and stacked atop and vertically interlocked with adjacent ones of the stackable interlocking support blocks of the first course in a stepped configuration.

20. A stair system comprising:
the multi-course support system of claim 19; and a plurality of concrete step blocks and/or concrete landing blocks supported by the multi-course support system.