Roofing System

The present invention relates to a roofing system employing a roofing membrane secured to the roof deck.

Roofing systems employing roofing membranes are known in the art. In such systems, the roofing membrane is supplied in the form of long strips. An edge of the first strip of the roofing membrane is secured to the flashing at the outermost edge or flashing means of the roof, by various methods, including a suitable adhesive, such as tetrahydrofuran, and the free edge is secured to the top of the roof by means of suitable fasteners that penetrate through the membrane into the roof deck. The next strip is laid parallel to the first strip by placing one edge of the second strip over the fasteners in the first strip and sealing the two edges together by means of an adhesive or by heat welding. The free edge of the second strip is then secured to the roof deck by means of fasteners and the process is repeated until the entire roof is covered with parallel strips of roofing membrane. Generally, the roofing membrane comprises three-plies, namely, outer plies of a polymeric material heat-bonded to each other and to an inner ply of a fabric, plastic or glass scrim.

In conventional roofing systems, only one edge of each strip of membrane is secured to the roof by means of fasteners, and to insure that the roofing system will withstand wind forces that are encountered during use, a large number of fasteners per lineal foot are employed. The operation by which the strips of membrane are secured to the roof by means of the fasteners is labor intensive. Hence, the cost of the fasteners themselves and the labor costs of installing the fasteners represent a significant portion of the total cost of the roofing system.

The present invention now provides an improved roofing system that is less labor intensive and less costly. In the system of the present invention, a three-ply roofing membrane is employed, preferably comprising outer plies of a polymeric material and an inner reinforcement. One edge of each three-ply membrane terminates in a cover flap consisting of one ply of material and a two-ply base portion consisting of the two other plies of material. The single-ply cover flap and the two-ply base portion are integral with the remainder of the roofing membrane. The polymeric material may be an elastomer or a non-elastomeric plastic.

A roof constructed according to the invention, comprises parallel strips of the roofing membrane according to the invention, with the three-ply edge of one strip being inserted between the cover flap and base portion of the adjacent strip, in tongue-and-groove fashion, and fasteners secure the strips to the roof deck by penetrating through the edge of one strip having three integral plies and through the base portion of the adjacent strip and thence into the roof deck.

The present invention is illustrated in terms of a preferred embodiment in the accompanying drawings, in which:

FIG. 1 is a plan view of a plurality of roofing membranes secured together to form the roofing system according to the invention;

FIG. 2 is an enlarged view, in section, taken along lines 2--2 of FIG. 1;

FIG. 3 is a greatly enlarged view, in section, of a roofing membrane according to the invention;

FIG. 4 is a plan view, with parts broken away, illustrating how roofing membranes are joined together end-to-end;

FIG. 5 is an enlarged view, in section, taken along lines 5--5 in FIG. 4; and

FIG. 6 is an enlarged view, in section, taken along lines 6--6 in FIG. 4.

As can be seen in FIG. 1, the roofing system according to the invention, comprises a plurality of roofing membranes 2-7 joined together along their longitudinal extending edges; it will be understood that sufficient strips of membranes are employed so that the entire extent to the roof is covered. Strips 2-7 are secured together by fasteners 8 in a manner to be described in detail below. Each of strips 2-7 comprises outer plies of polymeric material, such as PVC, chlorinated polyethylene or Hypalon, and an innermost ply of a reinforcing scrim, such as a 10.times.10 scrim formed of 1,000 denier, polyester fibre. Strips 2-7 are provided in the form of large rolls, and the ends of adjacent strips are often offset, as in the case of strips 3 and 4.

Referring to FIG. 2, it can be seen that each fastener 8 secures two membrane strips to the roof, such as strips 2 and 3 and 4 and 3. Fasteners 8 pass through the strips 2, 3 and 4, 3 and through layer 9 of insulation and thence into roof deck 10. Each of the membrane strips 2-7 is formed in the same manner and strip 2 is shown in detail in FIG. 3. Roof deck 10 is shown as being made of wood, but the invention is operable with any roof deck, such as steel or concrete or any other suitable material.

Thus, the strip 2 has outer plies 2a and 2b of polymeric or elastomeric material bonded to each other and to the reinforcing scrim 2c. At one edge 2d of the strip 2, all three plies are bonded together, while at the opposite edge of the strip 2, the top ply 2a is separated from the other plies 2b and 2c. Plies 2b and 2c may be bonded to each other to form a base portion, as shown, or scrim 2c may loosely overlie the base 2b. Top ply 2a functions as a cover flap, which can be folded along fold line F. Strip 2 may suitably be from 30-60 mils thick, but the thickness will be determined by such factors as the stresses encountered, the required durability etc.

With reference to FIG. 2, the edge 3d of stip 3 lies between the cover flap 2a and the base portion 2b, 2c of strip 2, and fastener 8 thus penetrates the three plies of edge 3d of strip 3 and the two plies of the base portion 2b, 2c of strip 2. Cover flap 2a is secured to the top of edge 3d by means of an adhesive or heat-bonding in a conventional manner, to create a water-tight roofing system. The edge of strip 3 opposite from edge 3d likewise terminates in a cover flap 3a and a two ply base portion 3b, 3c, and fastener 8 penetrates the three plies of edge 4d and the two plies of base portion 3b, 3c before entering the insulation 9 and the roof deck 10.

Additional strips of roofing membrane are laid edge-to-edge as described above so that the entire width of the roof is covered.

The ends of the strips are joined together as shown in FIGS. 4-6. Here, strips 2, 3, 5 and 6 are shown for simplicity, it being understood that the same pattern of attachment is followed for the other strips. Strips 2 and 3 overlie strips 5 and 6, respectively.

As shown in FIG. 4, an end of strip 5 is placed under the end of strip 2 after the lower, right-hand corner of the strip 2 is first removed by cutting the base portion 2b, 2c along fold line F to the point where the end of strip 5 will be located, and then cutting base portion 2b, 2c perpendicular to fold line F to the edge of strip 2. Cover flaps 2a and 5a are raised as a unit, and edges 3d and 6d (FIG. 5) of strips 3 and 6 are placed between cover flap 5a and base portion 5b, 5c and the fastener 8' will thus pentrate the three plies of strips 3 and 6 and the two plies of base portion 5b, 5c. Cover flaps 2a and 5a will overlie fastener 8' and these are secured to each other and to strip 3 as described above. Strip 3 overlaps strip 6 in the same manner as strip 2 overlaps strip 5. Fastener 8" (FIG. 6) penetrates the three plies of strip 6 and the two plies of the base portion 5b, 5c and is covered by cover flap 5a.

Through the use of the present invention, both edges of each strip of roofing membrane are securely fastened to the roof. Further, the fasteners pass through five plies of membrane, rather than three plies as in the prior art systems. Hence, the number of fasteners per lineal foot of membrane may be reduced for a given set of forces acting on the membrane as compared to the prior art, thus reducing the cost of fasteners and the cost of labor to install them.