GB2179688A - Building system - Google Patents

Abstract

A building system for the construction of walls is provided comprising the employment of prefabricated blocks having compound shapes which are such that at least a majority thereof each exhibit projections and/or recesses arranged to co-operate interlockingly with the projections and/or recesses of other blocks can be assembled without the essential use of mortar or other intervening binding material. Illustrated blocks are basically T-shaped, having a hollow formation and being laid in the plane of a vertical wall, in horizontal courses in the wall. Each block is inverted relative to its immediate neighbours.The hollow interiors of the blocks may be filled with strengthening material or heat and sound insulating material and/or reinforcing bars may extend through aligned hollow interiors in the superposed courses. Compound-shaped corner and junction blocks are employed, where required. <IMAGE>

Description

SPECIFICATION Building system This invention seeks to provide a building system in which bricks or blocks are employed that are of com- pound shape, that is to say, are not basically re ctangularparallelepipeds.Theterm "brick(s) or block(s)" will be shortened to "block(s)" alonethroughoutthe greater part ofthe remainder ofthis doc umentforthesake of brevity.

According to the present invention, there is provided a building system for planar structures, such as walls, floors, roofs, paths and roads, th e system co m- prising the employment of prefabricated blocks hav ing compound shapes which are such that they co- operate interlockingly with other blocks ofthe system, whereby said interlocking blocks can be assembled withoutthe essential use of mortar or other intervening binding material, and comprising the following feature::- a basically T-shaped such block, the block being formed with keying recesses and keying projectionsforengagingwith keying projections and keying recesses, respectively, of other such blocks, the keying recesses and keying projections having bevelled engaging surfaces which are in the form of substantially closed loops.

The block may co-operate with other compoundshaped blocks to produce buildings or otherstruc- tures in which the various blocks strengtheningly support one another with interlocking co-operation, it being possible for the buildings or other structures to be completed, in some cases, without mortar or other binding material between the blocks or, in other cases, to employ a relatively small amountof mortar or other binding material between the blocks as compared with buildings and other structures produced from conventional blocks.

The system advantageously employs blocks which are pre-fabricated to a high degree of precision and the required fitting together and/or interlocking of the blocks will not be achieved, during the erection of a building or other structure, unless the individual blocks are correctly disposed relative to one another and register accurately. If a mistake is made in positioning a block relative to others that have already been laid, the error will almost immediately be very obvious and can quickly be corrected. No cutting or breaking of any block is necessary since the system includes the use of complementary blocks such as end blocks, corner blocks, junction blocks and soon.

In the case of a building or other structure having up rig ht walls, a minimum of checking is necessary upon the erection of those walls once the dimensions ofthe base ofthe building has been calculated and said base has been accurately marked out. An impor ta nt featu re of the system is the fact that the same block can be employed in the construction offloors and roofs as are used to erect walls thus producing a fully integrated building system in which, once an initial choice of the various possible block shapes has been made, the number of different shapes of prefabricated block that are actually employed in a single building orotherstructurecan bequitesmall.

For a better understanding of the invention, and to show how the same may be carried into effect, the various basic forms of building block which an ex ample of this system employs will now be separately described, except inasmuch as different shapes of block co-operate with one another, reference being madeto the accompanying drawings which, sim ilarly, are grouped to relate as far as possible to the different shapes of building block. Reference is made firstly to Figures 1 to 20 of the drawings which Fig uresshowtheuseofbuilding blocksthatarebasi- callyT-shaped. Figures 1 and 2 of the drawings show two walls of a building or other structure formed from such T-shaped blocks.It will be seen that, in each horizontal course of blocks, neighbouring blocks are alternately upright and inverted and that, in the structure of Figure 1, each block is inverted re lative to blocks which are verticallythereabove a ndl ortherebeneath whereas, in the structure shown in Figure 2, each block in each course has the same dis position as does each block which is vertically thereabove and/ortherebeneath. It will particularly be noted that, in both cases,theT-shaped blockscooperate to form a 900 junction between two upright walls without the need to employ blocks of any other shape.It will immediately be apparent that the horizontal limb or crossbar of each block is three units wideandthatthevertical limboruprightthereofis two units tall measured from the lowermost ex- trem ity thereof to the top of the horizontal limb or crossbar.

In fact, the basic T-shaped block of Figures 1 and 2 is given tapered projections and depressions as shown in Figure 3 and Figure 4 or is provided with projecting nibs and matching recesses as shown in Figure 5. The bevelled engaging surfaces of the tapered projections and depressions and ofthetapered nibs and recesses of Figures 3 to 5 are in the form of substantially closed loops each of which thus out lines either a projection or a recess (Figures 3 and 4), or outlines a projection and a recess (Figure 5). These projections and recesses provide a significantly improved and strengthened key between the blocks en abling them to be fitted satisfactorily together without the use of mortar or other binding material when a wholly or principally dry construction is required.It will be apparentfrom Figures3to 5 ofthe drawingsthatthe blocks which are being described are of hollow formation and it is noted that the projections and recesses co-operate with each other to form a satisfactory seal atthejoints between the blocks which is a considerable advantage if the hollow blocks areto befilled with an initiallyfoamed or liquid insulation material or with foamed or other concrete.

Figures 6,7,8,9 and 10 ofthe drawings illustrate the formation and use of blocks which may conveniently be known as Z-key, T-blocks. The various views which are given in each of Figures 6to 10 ofthe drawings adequately show the compound shape of each basicallyT-shaped block and the compound shape of the co-operating Z-key, T-block. Figure 9 shows, on the left, the co-operation between two such blocksAand B atthe90 junction between,for example, two uprightwalls whereas the right-hand side of Figure 9 shows the similar co-operation be tween two T-blocks of simpler non-keyed shape (compare with Figures 1 and 2).Figure 10 is a plan view illustrating the use of dove-tailed basicallyTshaped blocks in co-operation with basicallyZ- shaped blocks and a "corner" block designed to cooperate with two neighbouring Z-blocks at the 90" junction between, for example, two uprightwalls.

The basically T-shaped blocks of Figures 6 to 10 of the drawings are, in any construction employing them, keyedtotheir neighbours on all sides and this produces an equilibrium between the forces acting on each block, it being noted that Z-keyed blocks are usable in slab form as floors and also in slab form as roofs which latter can be employed either with, or without, additional supports.

There are four basic versions of the embodiment of the system which principally uses T-shaped building blocks, these fourversions having been found to be themostsatisfactoryas regards ease of construction, handling, simplicity, ease of production ofthe blocks, versatility in use of the blocks and the need to produce a minimum number of accessory blocks for use at, for example, wall ends, wall junctions and the like. The first of these fourversions is illustrated in Figures 1 and 2, the second in Figures 11 to 17,the third in Figure 32 andthefourth in Figures 18 and 19.

Itwill be apparent that all ofthe embodiments shown in Figures lotto 19 inclusive employ the basicallyTshaped blocks lying on their sides (i.e. with their uprights horizontally disposed) and thatthe blocks shown in the fourviews of Figure 17 are basicallyT shaped having surfaces that are to co-operate with those of other blocks either cylindrically concave or matchingly cylindrically convex.

In the version of Figure 18, each basically T-shaped block is ofelongate formation, the blocks of Figure 18 being un-keyed whereas those of Figure 19 are shaped to key together, it being noted that elongate blocks of basically L-shaped cross-section are required in the embodiments of both Figures 18 and 19 where wall ends are produced and T-shaped (in plan view) junctions between walls are made.

In each ofthefourversionsofthesystemwhich principally employT-shaped blocks, the blocks may be solid, wholly or partly hollow and may have plain and or patterned or othertextured surfaces. It will be apparentthat many different combinations of precise shape, size, materials, surface texturing and so on are possible that are too numerous to discuss individually. The particular type which is chosen will depend upon individual preference, climatic conditions, geographic situation and local traditions of building.It is noted that, whilst prefabricated con crntewill generally be employed and most blocks will be hollow in construction, other materials can equallywell be used, if preferred, such as pre- stressed concrete to form blocks usable for walls, floors, roofs and soon but a construction employing concrete is not essential and the blocks can be made from,forexample,glass-reinforced plastics materials, natural wood and/or plywood.

The use ofthe building system which has so far been described enables strong buildings or other structures to be made either in dry form orsemi-dry form using very much less mortar or other binding material than is employed in the formation oftraditi onal brick/block buildings and the like. The described system has considerable advantages as compared with traditional building systems and these advantages include stability both during and after erection of a building or other structure, ease of erection, sim- plicity in aligning the blocks without long experience of such work being necessary and with the use of an absolute minimum of auxiliary tools, measuring in strumentsandothergadgets.The blocks can be such as to interlock giving increased strength to the wall, floor, roof or the like which is being produced whilst simultaneously eliminating errors such as discrepancies in level and the formation of crooked, zig- zag, curved or other incorrectly disposed courses of blocks. The system is versatile since it can employ different forms of keying and interlocking and can employ any chosen one, or any chosen combination, of the different blocks that have already been descri bed and those that will be described below. As well as being very suitable for the construction of dwelling houses and other buildings, the system can be used for many other purposes such as, for example, the paving of roads, pathways, pavements and the likeandforthecladding of new or existing buildings.

Although the blocks will usually be formed from conventional concrete, they can, as has already been mentioned above, beformed from other materials which include, in addition to the examples already mentioned, light-weight concrete, clay, gypsum and synthetic plastics materials whether or not reinforced with glass fibre or the like. Where appropriate, buildings or other structures can be produced without mortar or other binding material between the blocks but grouted cavities can be included, where required, for strength and/or insulation. If required, a building or other structure can be formed in such a way as to be capable of being readily dismantlable by including therein removable keying blocks and/or removable locking bolts.Although re ferred to generally throughoutthis document as being "blocks" the fourth version that has so far been described with reference to Figures 18 and 19 of the drawings can be considered also as constituting panels. The blocks or panels may be given surface textures designed to simulate the use of a traditional method of construction when viewing the exposed surfaces of a building or other structure formed from such blocks or panels.

Figure 20 ofthe drawings somewhat diagrammatically illustrates the use of the basicallyTshaped blocks, arranged as shown in Figure 1, infor- ming an irregularly shaped structure having a plura lity of right-angled corners and a number of access openings to its interior. It will be seen that, at the margins ofthe access openings, additional L-shaped blocks or cm bod blocks are required to produce upright straight edges.

It has been found that, using principallythe basicallyT-shaped blocks to form a building or other structure, those blocks, when accurately produced, fittogetherinthe mannershown in Figures 3 and 4or Figure 5 of the drawings in such a way as automatically to prevent inaccuracies in horizontal or vertical disposition, provided onlythatthefoundation or footing is itself correctly disposed. The interengage mentofthe blocks automatically prevents vertical and horizontal inaccuracies from occurring and the fact that said blocks fit tightly together produces a strength which is comparable with that achieved by using traditional bricks or blocks that are connected to one another by mortar or other binding material.

Considerable time is, of course, saved by wholly or principally omitting mortar or other binding mat erials sincethe builders do not haveto waitforthe mortar or the like to set before the blocks can be relied upon for supporting purposes. Although the blocks are pre-fabricated, a building or other structurewhich isto be formed principallytherefrom is actually constructed in a very similar manner to the use oftraditional bricks and blocks exceptthat, generally speaking, mortar is used very sparingly, if at all.

The final building or other structure will not have the appearance of a monolithic concrete mass but rather the appearance of a somewhat differently patterned, but otherwise traditional, block or brick construction thus avoiding an alien external appearance which tends to discourage builders and the customers for their products. Builders that work substantially only in the traditional way will find no difficulty nor strangeness in using this system since the system comprises placing a large number of relatively small blocks in pre-determined positions relative to one another as is, of course, done when using traditional bricks and building blocks. The present system does not envisage the use of relatively large prefabricated panels as formsthe basis of a number of modern methods of building construction.

As well as being employed in the construction of actual buildings, paths, roads and the like and the cladding of new or existing buildings, this system can be employed in producing either permanent or temporary shuttering, basically T-shaped blocks which are formed from glass fibre reinforced plastics materials or wood being particularly suitable for shutteriiig purposes. If exceptional strength is required in the blocks, they may be formed from glass fibre reinforced concrete but the particular choice of material will naturally depend upon the nature ofthe building or otherstructure that is to be formed and the purpose for which it is required.The hollow interiors ofthe blocks can, for extra strength, be filled with concrete or cement grout and it is possible to insert reinforcing bars into those interiors, before pouring the concrete or grouting, and it has already been mentioned that the hollow blocks can be filled with insulation material, such as urea-formaldehyde foam, by either pouring or injection.

The system is particularly convenientforforming temporary buildings or other structures since the blocks and other necessary items can be supplied in a partialiy assembled condition with post units bolted to beam units merely requiring the interlocking blocks to be correctly positioned. Undersuch circumstances it is, of course, necessarythatprovision shouldbemadefordisassemblingthetemporary building or other structure in one of the ways briefly discussed above.

it will be realised thatthe blocks or panels that have been described can be provided in any required sizes although, in the case of blocks, it is desirable thatthe size and weight should not exceed that which can readily be handled by a single workman. The panels that have briefly been described with reference to Figures 18 and 19 ofthe drawings can, on the other hand, be of such a size that mechanical assistance is required to move them, it being possible to provide panels otherthan those shown in Figures 18 and 19 toform a rangeofmodularunitsthatarebasicallyof T-shaped cross-section together with accessary units as may be required at wall ends, wall junctions, the marginsofaccessopeningsandthelike.Thesecond and third version ofthe T-blocks may, if required, be substantially brick-sized and may be made from baked clay and other materials from which conventional bricks are formed. In a building or other structure using such bricks, it is desirable to groutthe junctions between them at regular intervals, as may be necessary having regard to the particular building or other structure that is being produced, or, in the case of hollow bricks of this form, to fill them with mortarto produce columns or pillars and to strengthen the construction at the junctions between walls.

When erecting a building orotherstructure using the first version of the T-blocks that has been described with reference to Figures 1 and 2 of the drawings, it wili be remembered that these blocks do not possess any interlocking or keying features and it is therefore desirable, although notabsolutelyes- sential in all cases, to use mortar, grouting orother binding material in each pair or tier of blocks, using further mortar, grouting or other binding material between superposed pairs or tiers of blocks. The blocks that are required at the corners and ends of walls are basically similarto the T-shaped blocks themselves onlytheform of keying or interlocking has, of course, to match that employed in the T- shaped blocks.Figures 7,8,9 and 10 of the drawings show various constructions that can be employed at junctions between walls, the references A and B being employed to desigate co-operating blocks that exhibit Z-keying. It will already be apparent that the blocks of the second version are assembled in a sim ilarwaytothose of the first version except that each T-shaped block has its upright limb substantially hor izontally, ratherthan substantially vertically, disposed.

In employing the third version to form a building or other structure, much the same technique is used as withthefirstversion butthe relative disposition of the blocks is different, T-shaped blocks being employed whose thicknesses can be varied, and in particular reduced, to allow different external patterns to be produced togetherwith different cross-sectional relative dispositions ofthe blocks. This third version of the system can, if desired, be combined with the second version, using the two versions alternately in successive tiers ofthe blocks. The fourth version that is shown in Figures 18 and l9ofthedrawingsem- ploys elongate panels, rather than blocks, but it is noted that these basicallyT-shapedcross-section panels are of significantly smaller widths than panels employed in known pre-fabricated building systems which has the result that the individual panels are not too heavy inweightand can, if desired, be keyed to one another eliminating, where appropriate, the use of mortar or grouting between the panels. If required, the strength of a wall or partition formed from such panels can be increased by employing a top beam that may, if required, be bolted or otherwise secured tothetopsofthe upright panels.

Asecond basic embodiment ofthis building system employs blocks that are notT-shaped but that co-operate with one another by way of keys that are substantially Z-shaped. Such blocks are particularly, but not exclusively, useful in forming prefabricated panels,partitionsandthelike,a minimum ormortar or other binding material being required atthejunctions between the blocks.

The shape of the Z-key can be varied but it has been found convenient to employfour basic forms of Zkey any of which will join the blocks quickly and effectivelytogetherwithout essentially employing any mortarorotherbinding material.

It is possible to build a wall or other structure employing Z-keyed blocks in a semi-dryform overlaying every tier of Z-keyed blocks with mortar or other binding material to secure the superposed tiers together in a conventional way. If a fully dry con- struction is preferred, it is desirable to incorporate end keying systems of substantially M-, substantially S-, or substantial ry Z-form into the blocks to ensure that a building or other structure can be erected quickly and accuractelywhilst automatically maintaining stability and both vertical and horizontal alignment.

Figure2 1 ofthe drawings shows various views of a block and illustrates the first, third and fourth versions ofthe Z-key, Figure22 gives various views of a number of blocks provided with the first version ofthe Z-keyfitted together, Figure 23 is an elevational view showing a hollow block, provided with the second version ofthe Z-key from which it will be seen how said block will interengage neighbouring similar blocks.

Figure24 is a plan view showing walls of a building that are formed by employing hollow blocks exhibiting the first version of the Z-key but Figure 24 also showsthe shapes of blocks that are required at a right-angled junction between two walls, two forms ofT-shaped junction between walls and a cruciform junction between fourwalls, Figure25showsfurtherdetailsofthe basic blocks and junction blocks that are illustrated in Figure 24 and additionally shows, in black, one blockthat is required at the end of an upright wall when said end should present a flat surface that extends per- pendicula rly between the opposite sidefaces ofthe wall, and Figure 26 illustrates hollow Z-keyed blocks which are used as permanent formwork forthe construc- tion of beamstogetherwith detailsofonewayoffit- tingthose blocks tqgether and, at the top ofthe Figure, the shape of auxiliary hollow blocks that may be used surroundinglyto support upright reinforcing rods orthe like that are interconnected by strengthening wires.

The Z-keyed blocks that have just been described can be employed in much the same situations as the basicallyT-shaped blocks discussed above and, to a large extent, havethe same advantages, ascompared with the bricks or blocks that are employed in conventional building systems, as do those pre viouslydescribed blocks.

There nowfollows a description oaf third basic embodiment of blocks employed ion a building system which blocks are dove-tailed and will here inafter be called, for the sake of brevity "dove" blocks. Such blocks are again particularly, but by no means exclusively, useful in constructing prefabricated panels, partitions and the like, very little, if any, mortar or other binding material being required atthejunctions between the blocks. The dove blocks again employ Z-keys for interengagement and, once again, these Z-keys may be varied in shape but conveniently are provided in four different versions as has already been described above with reference to Figures 21 to 26 ofthe drawings.

As already briefly described with reference to Figures 21 to 26 ofthe drawings, the dove blocks can advantageously be used in buildings or otherstructures of semi-dry form, each tier of Z-keyed dove blocks being overlaid with mortar or other binding material to secure it to the superposed tier in a sub stantiallyconventional manner. Again, if a substanti allyfullydryconstruction is required, itis preferable for the dove blocks to incorporate end keys of one of the same forms, and for the same purposes, as have already been mentioned with reference to Figures 21 to 26 of the drawings.

Each dove block is actually shaped to comprise two half Z4orm blocks of symmetrically identical form, the two halves being integrally produced. This form of block has the particular advantage that, in use, the forces acting on the opposite ends thereof will almost always substantially counterbalance one another so that a particularly structurally stable building will result.

The dove blocks have substantially the same ver- satility of usage, and advantages as compared with the bricks or blocks that are employed in conventional building systems, that have already been discussed above in regard to the version ofthe system which principally employs basicallyTshaped blocks.

Figure 27 of the drawings gives several different views of a hollow dove block just described, and Figure 28 is a plan view, somewhat similar to Figure 24, showing a plurality ofthe hollowdove blocks 4 employed in walls which also include mat chingly shaped cruciform connecting blocks 1, "half" wall end blocks 2, T-junction blocks 3 and rightangled corner blocks 5.

A description will now be given of ways in which the various forms of blockthat have so far been described can be employed in forming buildings and other structures. When basicallyT-shaped or other blocks ofthe kind that have been described, having Z-keys, are used in co-operation with one another, the Z-keys will effectively lock adjoining blocks together by directing the forces which act upon the junctions between the blocks and otherwise upon the blocks themselves in such a way as to enhance or reinforce the stability ofthe structure that is com- posed of said blocks.In particular, the Z-keys transform the tensile forces to which the described blocks or slabs are subject into compressive forces which latter forces will not normally crush building materials of the kind used to produce blocks, bricks and slabs unless said forces are excessively strong.

Figurss29, 30and310fthedrawingsillustrate three different forms offloorthat may be constructed using the building system. Figure 29 shows the employment of the previously described dove blocks or slabs arranged in a pre-cast concrete or steel beam or timber joist framework that is of matching cross sectional shape and that provides said beams or joists at pre-determined substantially regular intervals.

Figure 30 is similar to Figure 29 but shows the use of basically T-shaped blocks or slabs, arranged with their uprights in horizontal positions, in aframework that is similartotheframeworkof Figure 29. It will be noted that the basically T-shaped blocks exhibit Zkeys of substantially the kind shown in Figure 23 and that similarly keyed dove blocks or slabs are also em ployed to fill the gaps which would be left if T-blocks or slabs alone were used.

Figure 31 ofthedrawingsillustratestheemploy- ment of Z-keyed blocks arranged between the beams or joists of a framework that is similar to theframework of Figure 29 except that said beams or joists necessarily have a cross-section which matches those of the blocks or slabs with which they are to co-operate.

It is important, when using the blocks in one of the waysthat s illustrated in Figures 29 to 31 ofthe drawings that said blocks should be forced tightly against one another in a horizontal direction that is perpendicularto the lengths of the beams or joists of the co-operating framework. Under such circumstances, the blocks or slabs will co-operate effectivelywith one another to form a stablefloorin which no underneath support, between the beams or joists, is necessary. A tie beam may often advantageously be emplloyed to maintain the blocksfirmly pressed against one another as just described, such tie beam being either pre-cast or cast in situ. The use of a tie beam for this purpose is particularly advantageous when the blocks are in the form of roof slabs.

Obviously, there is a limit to the span of blocks which will remain reliably interconnected, without support, merely by the co-operation oftheir own interlocking portions, this limit being dependent upon the sizes of the blocks or slabs that are employed, the strength of the material from which they are made and the load that, in use, they will be called upon to bear.lt is again possible to employ pre-cast or pre-stressed beams in supporting co-operation with the blocks or slabs, the blocks or slabs ofafloororthe like that is formed in this way needing no mortar, grouting or other binding material.

When using blocks or slabs that have Z-keys as shown in Figure 31, those blocks or slabs have symmetrically identical Z-keys at their opposite sides for co-operation with the neighbouring blocks or slabs and/or with the similarly keyed beams orjoists ofthe supporting framework. In the case of basicallyTshaped blocks or slabs as shown in Figure 30, each blockorslab has Z-keys at its two opposite sides which keys are identical, but not symmetrically ident ical, to one another. These keys are to be found both at the opposite sides ofthe upright of each basically T-shaped block or slab and at the opposite ends of the horizontal limb or crossbarthereof.If necessary, further strengthening can be produced by forming Z keys orsubstantially right-angled S-keys on the sur- faces ofthe floor blocks or slabs that are substantially perpendicular to the surfaces carrying the keys that have already been mentioned. Examples of such surfaces are those which are shown as facing a viewer of Figure 29, 30 or 31 of the drawings at the foot of each such Figure.

Blocks or slabs that have Z-keys attheir opposite sides and that, as can be seen in Figure 31, arethems elves basically Z-shaped in cross-section, are advantageously employed in erecting buildings and other structures, the blocks or slabs co-operating, as shown in Figure 31, with the beams and/or joists of a framework. It can sometimes be an advantage to secure pre-cast or pre-stressed beams together to form a slab and this has the advantage that said beams or joists will be lighter in weightthan is conventional, thus avoiding the need for heavy lifting machinery and other mechanical handling equipment to move various parts of the building or other structure that is being erected into their appointed positions.Once again, the advantage that the blocks or slabs automatically position themselves relative to one another in both vertical and horizontal directions is immediately attained. Also, since no mortar or other binding material is really necessary between the auto matically interlocking blocks or slabs, a roof can be placed on a building orotherstructureerected using this system without having to wait for mortar or other binding material to set and attain a required degree of strength.

When using the dove blocks to produce a floor or the like as shown in Figure 29, each block has Z-keys at its opposite sides and is inverted relative to its immediate neighbour(s). The form of construction is basically very similar that illustrated in Figure 31 and, similarly, the dove blocks can be formed as precast and pre-stressed slabs.

It remains only to emphasise that the various forms of key, which most of the blocks, slabs and panels that have been described exhibit, are intended for interlocking purposes rather than forjoining the blocks, slabs and panels together. The keys redirect the forces to which the blocks and soon are subject, when in use, in such a way as to strengthen the junctions between them and to strengthen the blocks, slabs and panels themselves. No mortar or other binding material is really necessary in most cases although, as has been described, there are circumstances in which the use of a minimum quantity thereof is advantageous. The blocks, slabs or panels can be formed from almost any material that has the required strength, durabiiity, resistance to the climate in which it will be used and that is not inherently hazardous (i.e. an otherwise suitable material that is highly inflammable orthatomits poisonous fumes when exposed to fire would clearly not be satisfactory).

Examples of the various keys that have been described are illustrated in the accompanying drawings as follows. TheM-key is shown in Figure 15, the substantially right-angled S-key is shown in Figure 14, the arcuate-key is shown in Figure 17,thefirstversion ofthe Z-key is shown in Figures 6 and 27, thesecond version of the Z-key is shown in Figures 7, 13 and 23, the third and fourth versions of the Z-key are shown in Figures 21 and 22, a wedge key which has previously been referred to as being an auxiliary block required atwall end and the margins of access openings and the like is shown in Figures 16 and 19whilst Figures 3 and 4 show the previously mentioned projections and depressions, which also act as keys, and Figure 5 shows the previously mentioned nibs and recesses which similarly act as keys.

Claims (6)

1. A building system for planar structures, such as walls, floors, roofs, paths and roads, the system comprising the employment of prefabricated blocks having compound shapes which are such that they co-operate interlockingly with other blocks ofthe system, whereby said interlocking blocks can be assembled withoutthe essential use of mortar or other intervening binding material, and comprising the following feature:-a basically T-shaped such block, the block being formed with keying recesses and keying projections for engaging with keying pro jections and keying recesses, respectively, of other such blocks, the keying recesses and keying projections having bevelled engaging surfaces which are in the form of substantially closed loops.

2. A system as claimed in claim 1, wherein the crossbar and the stem of the basically T-shaped block are each one unit in width in the plane of the T, the crossbar is three units long and the dimension of the crossbar and the stem perpendicularly to said plane is substantiallyone unit

3. A system as claimed in claim 1 or 2,wherein said substantially closed loops lie in planes per pendicularto the longitudinal axis of the stem.

4. A system as claimed in claim 3, wherein said substantially closed loops are located at the free end ofthe stem, at the two surfaces of the cross bar in the angles of the T, and atthe surface of the crossbarfacing directly away from the free end of the stem.

5. Asystem as claimed in any preceding claim, wherein each substantially closed loop encircles either a keying recess our a keying projection.

6. A system as claimed in any one of claims 1 to 4 wherein each substantially closed loop encircles a keying recess and a keying projection.