CA1309825C - Energy dissipation structure for securing lightweight roofing elements - Google Patents

Abstract

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ABSTRACT

A wind resistant inverted built-up roof construction is provided comprising a roof deck 9 a waterproof membrane overlying said roof deck, a plurality of closed cell foam plastic insulating material overlying said membrane, and a plurality of paving blocks overlying and supported by said insulating members in edge-to-edge relationship. A
plurality of resilient members is secured relative to said membrane and extend past the insulating blocks. A
plurality of hold-down plates respectively overlie a plurality of the paving blocks, and each plate is aligned with and secured to one of said resilient members in order resiliently to hold said paving blocks in place.

34,537-F

Description

~3~9825 1 ~

ENERGY DISSIPATION STRUCTURE
FOR SECURING LIGHTWEIGHT ROOFING ELEMENlS

For many years it was the universal practice to construct roofsi with a waterproo~ layer or membrane on the outer surface thereo~. Sueh roo~ing is still used in many installations, but has many disadvantages. The waterproof membrane, which may be built-up sheet materia} and asphaltic or bitumin, or which may be a single sheet o~ waterproo~ material, is exposed to extreme temperature variations, as much as 200F, to ultraviolet radlation, and to physical abrasion, all o~
- which have a detrimental ef~ect on the life o~ the roofing.
It has baen common practice for many years to provide insula'cion in roof construction, and when insulation i~ provided below th~e waterproof membrane, in the roofing system outlined above, it is necessary to provide a second waterproo~ membrane below the insulation to pr0vent moisture from within the building from condensing in the insulation and inhibiting or d stroying the insulating qualitie An alternative up-side down roo~ing construction i~ known in which the insulation is ~ ~:
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applied over the waterproof membrane, qee for example U.S. Patents 3,411,256 and 3,763,614. In this alternative roof construction the waterproof membrane, which may be a built~up membrane or a single waterproof layer such as a thermoplastic or an elastomer, is ~ applied directly to the surface of the roof. Blucks of foam plastic insulation are then applied over the waterproof me~brane. STYROFOAM (Trademark of The Dow Chemical Company) brand foam polystyrene plastic insulation is a superior product for such use. It is a tough, closed-cell, rigid plastic foam having excellent moisture resistance and high compressive strength.
The foam polyqtyrene plastic insulation placed over the waterproofing membrane rather than under the membrane protects the membrane from the effects of thermocycling, temperature extremes, and physica~
abuse, thus reducing maintenance and prolonging the life of the entire roofing system. It ha~ been found that the membrane so protected remains stable at temperatures below 100F even in hot summer weather. In fact, under normal conditions, the temperature of the membrane will remain within 15 to 20F of the building's inside temperature.
Typically, a polymeric fabric is installed over the foam to stabilize the system, and crushed stone or gravel ballast is applied to counteract the buoyancy of the insulation boards, to provide flammability resistance to the roof surface, and to shield ~he foam and fabric from ultraviolet radiation. As an alternative, paving blacks may be used in place of stone, particularly if traffic is to be expected on the roo~.

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In some such inverted roofing installations ut:llizing lightweight concrete paving blocks over foam plastic insulation, there is a tendency for the wind to lift the paviny blocks and insula~ion, and even to blow them from the roof deck. This is particularly true if each paving block and insulation slab is not thoroughly anchored to the roof deck. The situation can be particularly bad when the foam insulation and lightweight paving blocks are placed over unattached, single-ply membranes. The single-ply membranes can be pressurlzed from below, due to building pressures and/or wind pressure getting beneath the membrane. When such pressurization occurs, the membrane will tend to blllow or to form a balloon, and dump ~he paving blocks and insulation off the sur~ace and expose them to the wind.
It would be desirable to utilize energy dissipation means anchoring llghtweight concrete paving blocks on top of foam plastic insulation in an inverted built-up roof system.
More particularly, it would be desirable to provide energy dissipation means which is anchored to the underlying waterproQfing membrane wlthout interrupting the lntegri~y of the waterproofing membrane lying on top of the deck.
In accordance with the present broad invention there ls provided a wind-resistant built up roof construction compLis.ing a roof deck, a waterproof membrane overlying sa~d roof deck, a plurality of insulating members overlying sald membrane and comprising block~ of closed cell foam plastic resin materlal, a plurality of paving blocks overlying and supported by said insulating members in edge-to-edge relationship~ a plurality of ~ 3 ~

6~93-4221 resilient members secured relative to said membrane and exkending outwardly thereo~, a plurality of hold-down membexs each overlying a plurality of said paving blocks and aligned with one of said resilient members, and said resilient members including means extending between adjacent paving blocks and intarconnecting each hold-down member and a respective resilient member in order resllien~ly to hold said pavin~ blocks in place for permitting movement of the paving blocks under wind loads without substantial movement of the waterproof membrane relative to said deck.
In particular, this invention preferably uses a spring or other elastic means which is anchored -to the waterproofing membrane by means maintalning the integrity of a waterproof membrane overlying the deck. The spring or elastlc means extends above foam plastic insulating slabs overlying the waterproof membrane and is connected to a respective plate overlying the junction of three or four lightweight concrete paving blocks.
When a wind tends to lift the paving blocks and/or the foam plastic insulating slab, the spring or elastic means allows the paving blocks and ~he Poam plas~ic insula~ing slab to rise a limited extent, thus relievlng strains in the system. Upon diminution or cessation of the wind, the springs or other elastic elements return the paving blocks and insulating slabs ~o their normal position. The foam insulating slabs and concrete paving blocks can be separate, or they may be in~egral. For example, extruded polystyrene foam with a nominal 3~8 inch thick facing oP
latex modified concrete mortar (see U.S.

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Patent 4,067,164) can be used inqtead of the separate insulating slabs and paving blocks.
The present invention will best be understood with reference to the ~ollowing speci~ication when taken in connection with the accompanying drawings wherein:
Figure 1 is a partial perspective view o~ a roofing system constructed in accordance with the pre~ent invention;
Figure 2 is a cross-3ectional view taken, for example, substantially along the line 2-2 in Figure l;
Figure 3 i5 ,a perspective view of the parts shown in Figure 2;
Figure 4 is a view similar to Figure 2 showing the paving block~ a~ raised by a .wind;
Figure 5 is a view similar to Figure 1 showing a modification o~ the invention;
Figure 6 is a cross sectional view taken sub tantially along the line 6-6 in Figure 5;
Figure 7 is an enlarged view of the central portion of Figure 6; and Figure 8 is a view on a further enlarged scale of a portion of Figure 7, but showing the paving blocks a~ raised by the wind.
Turning now in greater partlcularity to the drawings, and ~irst to Figures 1 to 4~ there wlll be seen a built-up roof construction identified generally 34,537-F _~_ ~3~2~

by the numeral 10. The roof construction includes a roof deck 12 comprising a plurality of edge-to-edge wood boards 14 supported by suitable joists or girders (not shown). The roof deck 12 could equally well be o~
steel construction, or it could be concrete slab, suitably supported. A waterproof membrane 16 lies on and is qupported by the roof deck 12. This membrane could be a built-up construction compri~ing sheet material with asphalt or bitumin, or it could be a single waterproof layer, such as of thermoplastic material. An elastomeric material of a single thicknes~ al~o is a possibility, and the membrane is so illustrated.
Blooks or slabs of foam plastic insulation 18 lie on the membrane 16, and optionally may be cemented thereto. Alternatively, the cement blocks and in~ulation may be integral as roof insulation mentioned earlier. The insulation preferably comprises foam poly~tyrene plastic re~in. The concrete paving blocks substantially abut one another in edge and end relationship. The concrete paving blocks preferably utilize a lightweight aggregate, and preferably are reinforced by means such as continuous web or screen me3h, or chopped strands of fibers, although plastic such as polypropylene can be used. A fiber length of - 1~4 in~h t~ 1 in~h i~ prefera~le. The co~cr~e preferably i~ modified containing a latex, such as 3 styrene-butadiene latexl or an acrylic latex. Other latexes could be used. The paving blocks preferably are on the order of 1 inch thick and are on the order of 3 ~eet by 6 Peet. The thickness of the foam insulating panels depends on the degree of insulating quantity de~ired, but typically would be on the order of 1 to 6 inches. The polystyrene foam 34,537-F -6- ~

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, ~3~9825 is of the closed cell variety for moisture resistance, and the panels preferably are on the order oP 2 ~eet by 4 feet, although other~dimensions are contemplated.
The foam panels may simply be butted together, or may be interconnected by a shiplap or tongue and groove - construction.
The concrete blocks 20 may be laid ~o that the junctions between blocks may be in the nature of four-way Qrossovers. ~owever, prePerably adjacent blocksare oPPset longitudinally as shown in Figure 1 so that the intersection~ among adjacent blocks are in the nature of T-intersections. Each intersection is covered by a thin steel plate which preferably is round or rectangle in outline, and which is corrosion-resistant, being galvanized, or stainless steel, although other corro3ion-resistant metals or materials may be qati~factory. As may be seen in Figures 2 to 4, one end 24 of a spring 26, pre~erably a helical spring, is secured to a respective disk or plate 22, such as by welding. The spring also is corrosion-resistant, and may be galvanized steel or stainless steel. The upper end 24 of the spring Pit~ through an opening 28 between block~ This apening may be formed by notching the block~, or by qimply spacing the blocks slightly. The spacing illustrated in Figures 2 and 4 is greater than is actually ne~ ry~ a~d is P~r p~rp~se~ o~
illu~tration. Most of each spring 30 extends through a 3 vertical hole 30 through the foam plastic insulation 18, and this may be formed by slightly spacing adjacent blocks oP insulation, but prePerably is a specially-formed tubular hole through the insulation. The lower end 3Z of each spring is formed by the terminating hook 349 and this hook fits over a crosspin 36 in an 34~537-F -7--, 3~1~82~

~8--upwardly opening recess 38 in an upstanding boss 40 formed integrally with the membrane 160 The undersurface of the foam plas~ic insulation may be recessed at 42 to accommodate the boss. However, the boss is somewhat exaggerated in size in the drawings for purpo~es of illustration and the compressibility of the elastomeric substance of the membrane and of the foam plastic insulation may be enough to accommodate without the neces~ity of providing a specific recess 42.
Normally the springs 26 and disk3 or plates 22 hold the concrete blocks 20 d~wn flat on top of the foam insulation 18, and hold the insulation down tight against the membrane 16. However, in the case of a strong wind which might tend to raise and blow off the blocks 20, the blocks may raise up against the forces of the springs 26 as shown in Figure 4. The foam insulating slabs 18 may also rise, although this is not specifically illus~rated. This relieves ~tresses on the roofing system, and upon diminution or subsiding of the wind, the concrete blockq 20 will again be pulled down on top of the foam plastic insulation slabs as shown in Figures 1 and 2.
A modification of the invention is shown in Figures 5 to 8. Many of the parts are the same as or similar to those previously disclosed and are identified by sl~ilar reference numerals with the addition of the suffix a to avoid repetition of de~cription. The distinction lies in the anchoring or hold-down structure which uses an elastic material rather than a metallic spring, and which uses a two piece metal or plastic structure for anchoring to the roof deck without disturbing the integrity of the 34,537-F -~-:L30~825 membrane. Thus, as seen in Figures 6 to 8, the hold-down structure comprises a hollow anchor block 44 o~
metal or plastic const~uction having a flat bottom wall or floor 46 with a screw shank 48 secured to the bottom thereof by suitable means such as welding or cementing `~ for securing the box or body 44 to the boards 14a o~
the roof deck 12a. The body 44 further includes a ~lat top wall 50 parallel to the bottom wall or floor 46, and a serrated or pleated side wall 52. The side wall 52 may qimply consist of alternating hills and valleys, but more preferably is arranged a~ a screw-threaded ridge and valley. The membrane 16a is provided with an up~tanding portion 54 fitting over the body 44. This may be accomplished by using a heat-softenable pla~tic resin for the membrane, or the membrane may be manufactured with upstanding portions thereon. An ela~tomeric rubber membrane such as ethylene-propyIene-diene or butyl rubber will ~tretch over the hold-down structure.
An outer shell 56 substantially conforms to the exterior o~ the body or box 44 and comprises a flat top wall 58 and a serrated or pleated side wall 60 having alternating ridge~ and valleys. The outer shell 56 grips the upstanding portion 54 of the membrane 16a about the body or box 44O Assembly is not difficult in th~ ea~ o~ a s-c~th~a~d sid~ w~ll. If si~ply alternating ribs and valleys are provided parallel to 3 one anotherl then either the ribs and valleys must not be too deep, or the side wall must have vertical slots to allow it to expand to ratchet over the body or box 44.
A vertical tubular shank 62 extends between confronting concrete blocks 20a. The thickness o~ the 34,537-F _g_ ~3~982~

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shank may require notching of the blocks, although they may simply be spaced apart a bit farther than in the first embodiment o~ the invention. The tubular shank 62 is made of an elastic material 9 preferably an ~lastomeric or rubber-like material which has an upper generally circular ~lange integral with the shank and bonded to the lower ~ace of a respective disk or plate 22a. Similarly, there is an integral lower ~lange 66 on the vertical tubular shank 52 which is bonded to the upper face of the top wall 58 o~ the outer shell 56.
Norma~ly the parts are held in the position shown in Figures ~ and 7 with the concrete blocks 20a resting on top of the foam plastio insulation slabs 18a, and the latter lying on the upper surface of the membrane 16a. In the case of a wind that might tend to raise the concrete blocks 9 the~ vertical tubular shank 62 will stretch to allow the blocks to rise as shown in Figure 8. The insulating slab may also rise, although this is not specifically illustrated. Upon diminution or ce~sation of the wind, the elasticity oY the material of the vertical tubular shank 62 will again return the parts to the position shown in Figures 6 and 7.
It will be observed that the modification of the invention shown in Figures .5 to 8 has an added advantage o~ anchoring the membrane 16a to the roo~
deck 12a without requiring adhesives~ this being accomplished by the gripping of portions of the membrane by the bodies 44 and outer shells 66 at spaced locations.
In both embodiments of the invention illustrated, the overlying disks or plates 22, 22a span :
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joints of the concrete paving blocks to hold them down resiliently by means of the corresponding spring or elastic member. The concrete blocks are held down without disturbing the integrity o~ the waterproof diaphragm. The resulting roof construction is wind-~ resistant in that the concrete paving blocks can rise up against the resilient ~orce of the springs or elastic members to relieve stresses in the roo~ing system. The resilient anchoring structure promptly restores the concrete paving blocks and the foamplastic insulation if necessary to rest position on the rooY deok.
The specific examples of the invention a~
herein 3hown and described are for illustrative purposes only. Various changes in structure will no doubt occur to those skilled in the art and will be understood as forming a part of the present invention in~ofar as they fall within the spirit and soope of the appended claims.

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Claims (11)

1. A wind-resistant built up roof construction comprising a roof deck, a waterproof membrane overlying said roof deck, a plurality of insulating members overlying said membrane and comprising blocks of closed cell foam plastic resin material, a plurality of paving blocks overlying and supported by said insulating members in edge-to-edge relationship, a plurality of resilient members secured relative to said membrane and extending outwardly thereof, a plurality of hold-down members each overlying a plurality of said paving blocks and aligned with one of said resilient members, and said resilient members including means extending between adjacent paving blocks and interconnecting each hold-down member and a respective resilient member in order resiliently to hold said paving blocks in place for permitting movement of the paving blocks under wind loads without substantial movement of the waterproof membrane relative to said deck.

2. A roof construction as set forth in Claim 1 wherein each hold-down member comprises a flat plate.

3. A roof construction as set forth in Claim 2 wherein each flat plate comprises a disk.

4. A roof construction as set forth in Claim 1 wherein said membrane is secured to said roof deck and wherein said membrane is provided with a plurality of anchors to which said respective resilient members are secured.

5. A roof construction as set forth in Claim 1 wherein each resilient member comprises a spring.

6. A roof construction as set forth in Claim 4 wherein each resilient member comprises a spring.

7. A roof construction as set forth in Claim 1 wherein each resilient member comprises an elastic member.

8. A roof construction as set forth in Claim 7 wherein each hold-down member comprises a flat plate, and said resilient member is attached to the lower surface of said plate.

9. A roof construction as set forth in Claim 1 and further including a plurality of base members disposed under said membrane and anchored to said deck, a like plurality of overlying members each respectively gripping a section of said membrane to one of said base members, said resilient member respectively being connected to said overlying members.

10. A roof construction as set forth in Claim 9 wherein each resilient member comprises an elastic member.

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11. A roof construction as set forth in Claim 10 wherein each hold-down member comprises a flat plate, and each elastic member is attached to a respective flat plate and to a respective overlying member.

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