In situ roofing composite and method

The invention comprises a built-up roof material that has a composite membrane that is formed and affixed to the roof substrate in a single step. The membrane comprises a sheet of heat-resistant, non-woven polyester sandwiched between layers of asphalt. The upper asphalt layer is caused to flow through the polyester and meld with the lower layer of asphalt to form a homogeneous composite.

FIELD OF THE INVENTION 
This invention relates to roofing construction materials and methods, and 
more particularly to an in situ roofing composite and method of 
fabricating same. 
BACKGROUND OF THE INVENTION 
In recent times, the use of asphalt-impregnated polyester sheet for roofing 
construction has been found to provide excellent results. The polyester 
sheeting is generally treated with asphalt and other water-resistant 
materials in the factory, because of the difficulties experienced with 
applying water-proofing materials to the polyester at the roof site. 
Untreated, non-woven polyester sheet does not generally withstand heat, and 
does not easily absorb hot asphalt. 
Untreated, polyester sheet has been used with asphalt in cold-process 
roofing systems, wherein the asphalt is modified with latex or 
polypropylene and sprayed in a cold liquid state upon the polyester sheet. 
The cold process roofing systems have not been entirely satisfactory, 
because they tend to remain tacky for many months. This tackiness hinders 
the completion, repair and/or inspection of the roof, since the roof 
cannot be walked upon while tacky. 
Even where hot asphalt systems have been contemplated with the use of 
polyester sheet, the asphalt generally requires torching on the roof, 
which is an unsafe, fire-hazardous procedure. 
Therefore, most roofing applications using polyester materials have been 
with a polyestermat, i.e., a factory asphalt-impregnated polyester sheet. 
The drawback of using factory impregnated polyester sheeting, however, is 
the high cost and inconvenience of shipping and handling these heavy rolls 
of material. 
The present invention contemplates the construction of a roof using a 
polyester-hot asphalt or coal tar process at the roofing site, without the 
aforementioned disadvantages. 
Hot, built-up roofing can now use plain, non-woven polyester sheet for the 
reasons that the polyester is now being manufactured with a resin 
treatment that assists the polyester to withstand the temperature (450 
degrees F.) of hot asphalt and other hot-applied water-proofing 
ingredients. 
In addition, torching the asphalt on the roof is no longer necessary with 
the advent of a new hot pumping system, wherein the asphalt is pumped in a 
hot fluid state to the roof. 
The advantages of building-up a roof with hot water-proofing ingredients 
and polyester sheeting are many. 
The rolls of plain, non-woven polyester sheet are light in weight and 
inexpensive to purchase and ship. 
Plain polyester rolls are easier to work with, and a single, light-weight 
ply is often all that is required to produce an efficacious roof 
construction. 
According to this invention, the polyester and asphalt layers can be melded 
together and simultaneously directly attached to the roof substrate as a 
composite membrane. This inventive method of forming and affixing a 
composite membrane simultaneously, in situ, not only reduces the costs of 
fabrication, but also provides a roof of better quality and adhesion. 
The inventive method and construction will be explained in more detail, 
hereinafter. 
The composite membrane technique of this invention can be used with 
different roof substrates and overlays of foam, such as polyurethane and 
isocyanurate, to provide a roof composite construction of exceptional 
durability. 
DISCUSSION OF RELATED ART 
The use of a woven polyester sheet for cold process roof systems using an 
emulsion of latex and asphalt is shown in German Pat. No. 2200881. This 
technique is not similar to this invention in that a cold process is used 
rather than a hot process, and a woven rather than a non-woven sheet of 
polyester is utilized. Such a system using an asphalt emulsion will remain 
tacky, and as such, is not practical. 
In the U.S. Pat. No. 4,230,762, issued to Iwasaki et al; on Aug. 15, 1978, 
a non-woven fabric which is impregnated at the factory with asphalt, is 
described. This patent does not suggest using a plain, unpregnated 
polyester sheet in situ. As previously described, factory impregnated 
material is expensive to ship due to the added weight, and is further 
difficult to handle. 
In U.S. Pat. No. 3,369,958, issued to H. Fleeman on Feb. 20, 1968, an 
embossed sheet of polythene or polyvinyl chloride is suggested as a 
material which can withstand the heat generated by hot asphalt roofing 
techniques. This patent does not suggest the specific use of polyester 
sheeting. Also, this patent does not suggest the flow of asphalt through 
the sheet to form a composite membrane, and one which can be directly 
applied in one step. 
BRIEF SUMMARY OF THE INVENTION 
This invention features a built-up, in situ roofing composite having a 
membrane that is both formed and affixed to a roof substrate in a single, 
simultaneous step. The roofing composite comprises a first layer of 
water-proofing ingredients applied to a roof substrate. The ingredients 
can be selected from a group consisting of asphalt, modified asphalt and 
coal tar. 
Over this first layer, at least a single ply of non-woven polyester 
sheeting is laid. The polyester sheet has an approximate weight in the 
range of 4 to 14 ounces per square yard. Preferably, the polyester has a 
weight of approximately 5.5 to 7.5 ounces per square yard. 
A second layer of water-proofing ingredients is applied over the polyester. 
The second layer of ingredients is allowed to flow through the polyester 
and meld with the first layer, thus forming a built-up composite membrane 
that is affixed to the roof substrate. 
Over the membrane composite is applied a heat resistant layer of material, 
such as gravel, foam or a layer of mastic followed by granules. The foam 
may be a polyurethane or an isocyanurate. Similarly, the roof substrate 
may comprise a foam. 
The polyester sheet may be embossed prior to its installation to give the 
sheeting improved suppleness and adhesion. 
The composite roofing made in the above manner exhibits a durability 
uncommon with present day techniques and is substantially split-resistant. 
It is an object of the invention to provide an improved roof composite and 
method of fabricating same. 
It is another object of this invention to provide a roof composite that 
includes a membrane that is formed and affixed to the roof substrate in a 
single, simultaneous step. 
These and other objects of the invention will be better understood and will 
become more apparent with reference to the subsequent detailed description 
considered in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
Generally speaking, the invention features a built-up, in situ roofing 
composite, wherein a water-proof membrane is formed and affixed to a roof 
substrate in a single fabricating step. The composite and method of its 
fabrication will be described with reference to FIGS. 1 through 3, wherein 
like elements have been assigned the same designation for the sake of 
brevity. 
Now referring to FIG. 1, a roof composite 10 attached to a roof substrate 
11 is illustrated in a sectional view. The composite 10 is made up of 
several layers of materials, the first of which is a layer of asphalt 12. 
The asphalt can be applied in a temperature range of between 350 degrees 
F. to 480 degrees F. depending on the type of asphalt used, i.e., dead 
level, flat or steep. Modified asphalt (treated with latex) as well as 
coal tar may be used for layer 12. 
Preferably a steep asphalt is applied. The asphalt is heated to 450 degrees 
F. in a temperature-controlled bulk tanker. The tanker keeps the asphalt 
at a constant temperature, critical for successfully applying polyesters. 
Using a bulk tanker also enables the crew to start the job as soon as they 
get to the site, rather than having to wait for the asphalt to heat up. It 
provides a steady supply of hot asphalt, keeping production rates high. 
Plus, the tanker eliminates smoke and fumes, is safer than kettles, and 
uses less propane. 
The asphalt is pumped up to an asphalt spreader or a small hot lugger. One 
mechanic spreads about 50 pounds per square feet of the hot asphalt with a 
mop. 
Over the asphalt layer 12 is disposed a layer 13 of resin-treated, 
non-woven polyester. The resin treatment allows the polyester to withstand 
the heat of the asphalt. 
As the asphalt is mopped onto the roof substrate 11, another worker unrolls 
a 50 lb. roll of the polyester sheeting into the asphalt layer 12. 
Another worker then covers the polyester sheet layer 13 with another 50 
pounds per square feet of asphalt, thus forming layer 14. The asphalt 14 
is allowed to penetrate the polyester layer 13. 
The polyester sheet is 68 mils thick, so it requires a lot of asphalt to 
fill the polyester layer 13. 
The asphalt layer 14 is broomed into the polyester layer 13 to ensure good 
penetration. The asphalt is broomed sideways across the polyester, so that 
the polyester is not stepped on by the worker, and the underlayer of 
asphalt 12 is not displaced. 
The penetrating asphalt layer 14 melds with the underlayer 12 and then 
rises back up through the polyester layer 13. 
When the asphalt layer 14 is "broomed-in", a polyester and asphalt 
composite membrane is formed and securely attached to the roof substrate 
11 all in one step. 
The asphalt layer 14 must be shielded from the harmful ultraviolet rays of 
the sun. Also, the polyester layer 13 must be kept cool. Therefore, a 
heat-resistant insulating layer is required over the asphalt layer 14. 
FIGS. 1 through 3 show three different ways of covering the membrane 
composite. 
FIG. 1 illustrates a first method wherein a mastic layer 15 is coated over 
asphalt layer 14, and then a layer of ceramic granules 16 is embedded in 
the mastic layer 15. 
The mastic layer 15 comprises asphalt in a solvent, such as mineral 
spirits. Asbestos or fiberglass may be added to the mastic composition. 
The granules 16 are poured into a ground-level machine manufactured by 
Kold-King of Denver, Colo. that pumps them to the roof and sprays them 
over the mastic layer 15. 
In FIG. 2, a layer 17 of gravel is directly applied on top of the asphalt 
layer 14. 
In FIG. 3, a layer 18 of foam is applied over the asphalt layer 14. The 
foam can be a polyurethane or an isocyanurate made by the Upjohn Company. 
The substrate 11 of the roof can be the roof top surface or it may comprise 
a foam applied over the top surface. The foam for the substrate 11 can 
also be a polyurethane or isocyanurate. 
The foam in layers 11 and/or 18 can be sprayed or applied in blocks or 
sheets. 
The polyester sheeting can be laid in single, double or triple ply. The 
polyester sheet can range in weight from 4 to 14 ounces per square yard. 
The resin-treated non-woven polyester sheet is made by the Hoechst Company, 
New Jersey under the tradename of Trivera.RTM.. 
Another polyester sheet that can be used in hot-roofing systems is made by 
Du Pont Co. of Wilmington, Del., called Reemay Hot. This sheet is a 
polyester and fiberglass laminate. 
The granules 16 are type 11 made by the 3 M Company of Bellmede, N.J. 
Granules can also be purchased from GAF Corporation. 
The mastic can be purchased from the Monsey Corporation of East Rutherford, 
N.J. 
The asphalt can be purchased from the Exxon Corporation. 
The roof composite of this invention is substantially split-resistant. This 
is very significant, since the major cause of failure in contemporary 
roofing is splitting. 
Having thus described the invention, what is desired to be protected by 
Letters Patent is presented by the subsequently appended claims.