WO2001096678A2

WO2001096678A2 - Method of constructing and adhering a composite roofing product

Info

Publication number: WO2001096678A2
Application number: PCT/US2001/019086
Authority: WO
Inventors: Fred A. Fensel; Frank Janoch; Mark Ricigliano
Original assignee: The Garland Company Inc.
Priority date: 2000-06-15
Filing date: 2001-06-15
Publication date: 2001-12-20
Also published as: WO2001096678A3; AU2001269817A1

Abstract

A composite roof structure having two strata is supported by a roof substrate (3), which may be either a deck of a new roof or may be a previous roof. The stratum directly atop the roof substrate (3) is foamed-in-place insulation (8), with a lower surface thereof directly adhered to the roof substrate (3). The second stratum is a roofing membrane (5) having a bottom and a top surface, the bottom surface adhered to the upper surface of the insulation (8) by a pressure sensitive adhesive (1) initially disposed on the bottom surface of the membrane (5).

Description

METHOD OF CONSTRUCTING AND ADHERING A COMPOSITE ROOFING

PRODUCT

The present invention relates to a construction of a composite roofing product in which a sprayed-in-place foam insulation is covered by a water-tight self-adhering modified bituminous membrane. The invention also relates to attaching such a composite roofing product to a roof substratum or deck. The invention may be used in association with both new roofs and in re-roofing applications.

Background of the Invention In constructing a typical roof, a substratum or roof deck is applied to the structural elements of the building. Roof deck materials are typically comprised of wood, metal, or concrete. An optional insulation stratum may be applied atop the roof deck underneath the waterproof roofing membranes. One such insulation stratum would consist of insulation stock boards, typically in 4 ft by 4 ft or 4 ft by 8 ft size. These boards would be attached to the substratum by means of adhesives or mechanical attachment. Typical conventional roof membranes are rubber or bituminous-based products. Polyurethane foam ("PUF") roofing as used in the industry and as a component of the present invention differs from the conventional rubber or bituminous-based roofing products in that a rigid sprayed in- place polyurethane foam is applied to the substrate acting as both a waterproof roofing membrane stratum and an insulation stratum. Such a sprayed in-place rigid polyurethane foam lacks protection from ultraviolet radiation ("UV"), so it would typically be covered by a UV protective coating such as an acrylic, silicone, or polyurethane, etc, or, gravel or another mineral aggregate to form what is known as a Polyurethane Foam Roof. While the use of sprayed in-place foam as a waterproof roofing membrane is known in the art, it has never been customary practice to combine them with a conventional roofing membrane acting as a cap sheet to provide a single roofing system.

The conventional waterproof roofing membranes known in the prior art comprise two basic categories: 1) rubber or single ply; and 2) bituminous-based, modified bitumen or asphaltic sheets, as well as built-up roofing ("BUR").

The rubber or single ply waterproof roofing membranes are sheet products with a thickness ranging from about 30 to about 60 mils. Some may be reinforced with fabric. The primary materials used include EPDM rubber, HYPALON, poly(vinyl chloride) and others. The bituminous-based, modified bitumen and asphaltic membrane products are, of course primarily bitumen or asphalt, but they may be modified by at least one of the following: atactic polypropylene (APP), amorphous polyoelfin (APO) or styrene- butadiene-styrene (SBS). They typically range in thickness from 50 to 200 mils and are completed coated and are waterproof. These membranes may also contain secondary modifiers, such as styrene-ethylene (SE), styrene-isoprene-styrene (SIS), or styrene- ethylene- butadiene-styrene (SEBS). These membranes will typically have backing materials on the bottom side that act as a parting agent in manufacturing/processing. These backing materials must also allow and provide adequate adhesion between the substratum and membrane in the composite roof membrane construction. Backing materials may include limestone, silica, quartz, coal slag, or other similar mineral type materials as well as matting made of polyester, glass fiber or other materials. Top surfacing materials may comprise these same materials, although one difference may be the use of a UV protective coating or the use of a white or colored ceramic coating roofing granule as the top surfacing material. The asphaltic sheet products will be similar to modified bitumens, except that they contain no polymer asphalt modifiers. BUR sheet products are the same as the asphaltic sheet products, but much thinner in the range of 15 to 40 mils, not independently watertight, coated with parting agents on both sides, and always used in a ply/single construction with asphalt. Self-adhering membranes are waterproofing membranes of the type described above, but which have a pressure sensitive adhesive on the bottom side of the sheet material. Usually these are asphaltic based compounds that contain SBS, SIS, tackifying resins, oils, anti-oxidants, and other ingredients. These membranes may be just plain filled asphalt or modified bitumen. While it is not known art or common practice to combine a bituminous based roofing membrane with a sprayed in-place foam roofing, especially a polyurethane foam, it is known to combine a rubber-based roofing membranes to sprayed in-place foam. For example, U.S. Pat. 4,996,812 to Venable teaches an EPDM rubber roofing membrane with a fleece backing being adhered atop a sprayed in-place polyurethane foam roofing through use of a sprayed polyurethane foam adhesive. The fleece backing is apparently needed to promote adhesion between the EPDM membrane and the adhesive.

While the prior art teaches both the use of conventional rubber- or bitumen-based membrane roofing, sprayed in-place polyurethane foam roofing, and, to a limited extent, fleece-backed EPDM rubber membrane adhered with polyurethane foam adhesive to sprayed in-place polyurethane foam or insulation board stock, the prior art does not teach the application of conventional bitumen-based membrane roofing, and particularly, self- adhesive bitumen-based membrane roofing, atop sprayed-in-place foam insulation to provide a composite roofing system.

Summary of the Invention

This advantage and other advantages of the present invention are provided by a composite roof structure supported by a roof substrate. The composite roof structure comprises two strata: a first stratum of foamed-in-place insulation, a lower surface thereof directly adhered to the roof substrate and an upper surface; and a second stratum of roofing membrane having a bottom and a top surface, the bottom surface adhered to the upper surface of the insulation by a pressure sensitive adhesive initially disposed on the bottom surface of the membrane.

Brief Description of the Drawings

The present invention will be best understood when reference is made to the detailed description of the invention and the accompanying drawings, wherein identical parts are identified by identical reference numbers and wherein: FIGURE 1 is a perspective view of a foam insulation being applied to the roof deck;

FIGURE 2 is a side sectional view of the present invention as applied to a roof; and

FIGURE 3 is a top plan view of the present invention as shown in Fig. 2 with sections peeled back to reveal underlying strata.

Detailed Description of the Preferred Embodiment

Roof Preparation The present invention may be used atop a roof substrate, which could comprise a new roof deck of a structure in some instances and may comprise a previous roof in other instances. In either case, proper preparation of the surface onto which the present invention is to be installed is considered vital to the successful installation. The present invention will be understood through reference to Figs. 1 through 3. All surfaces to be covered must be clean, dry, and sound. All wet areas must be eliminated and loose materials removed. When roofing over an existing gravel built-up roof (BUR), all loose gravel must be removed and dirt and debris vacuumed or blown off. In the case of an existing polyurethane foam roof, having a sprayed in-place rigid foam covered with a UV protective coating such as silicone coating or any other coating on which good adhesion would not be able to be achieved, the surface coating and top surface of the foam must be scarified, or removed by mechanical means of cutting, and, or grinding. The scarfication remains must be thoroughly removed and cleaned. Existing metal roofs or decks should be clean and free of rust, oil, or dirt. Quite often insulation board stock is mechanically attached to provide a level surface on which to apply the system covering or spanning the flutes of a metal roof system. This same philosophy is also applied over single ply roofs or other substrates where obtaining proper adhesion of the sprayed in-place polyurethane foam would be a problem. Wood decks and thoroughly cured concrete decks often require a primer to be applied before applying the foam.

Foam Insulation In one aspect of the invention, a two component polyurethane is used. The foam insulation 8 of Fig. 1 is composed of polyol and diisocyanurate components pumped from drums and mixed within the body of an applicator gun 2. The mixed components are then discharged onto the substratum 3. A wide range of polyurethane foam systems for roofing are available from many different manufacturers in various densities, each exhibiting different temperature limitations, combustibility characteristics, etc. A typical installation thickness will range from about 0.5 inch per pass to about 2.5 inches per pass. A directory of suppliers of these materials can be readily obtained, such as from the Directory &

Buyers' Guide to Polyurethane Foam Insulation Systems published by the Spray

Polyurethane Foam Division, The Society of the Plastics Industry Inc., Washington DC.

In this particular aspect of the invention being described, the foam insulation 8 will be of the closed cell type and will have these approximate physical requirement characteristics as required by the Polyurethane Foam Contractors Division, The Society of the Plastics Industry, Inc., Washington, DC:

Properties ASTM Test Value Units

Density(sprayed in place) D-1622 2.8-3.0 lbs/ cubic ft

Compressive Strength D-1621 40 psi(minimum) lbs/in.

Closed Cell Count D-2856 90% (minimum) % Value

R-Value 6.2 aged Flammability E-84 <75

Smoke E-84 <450

In the composite roof system of the present invention, the base waterproofing/insulating stratum should exhibit a compressive strength in the range of from about 20 to about 40 pound per square inch. The standards for flammability and smoke are used solely to measure and describe properties of products in response to heat and flame under controlled laboratory conditions. This numerical flame spread rating is not intended to reflect hazards presented by this or any other material under actual fire conditions. The physical characteristics of the foam insulation 8 as described above have been set by the industry, however, foam with densities as low as about 2.2 lbs/ft³ and compressive strengths down to 30 psi have been found acceptable, and a suitable foam will be able to be selected for a particular situation, including accommodation of local building codes, by one of ordinary skill. This type of rigid spray polyurethane foam insulation is considered as the waterproof membrane or component in traditional PUF Roofs which receive a reflective topcoat or protective coating to shield the foam from UV radiation which would otherwise rapidly degrade it. Specifications for PUF Roofs require application of at least a protective base coat within 2 to 24 hours after foam application. This same specification should be met if construction scheduling does not allow for the self adhering modified bitumen membrane to be applied within that time frame.

Membranes The modified bitumen sheet used to cap the sprayed in-place foam of the present invention will have a layer of pressure sensitive adhesive on a bottom surface thereof. Typically, the pressure sensitive adhesive will be coated onto the bottom surface of the modified bitumen membrane during manufacture. In such a case, it will be typical to cover the adhesive layer with a release liner over it to allow for manufacturing, rolling, and to prevent coating adhesion degradation. In the aspect of the invention being described, the pressure sensitive adhesive is usually asphaltic based, however, although not necessarily a requirement. It will be well known to those of skill in this art to embed roofing granules in the top surface of the modified bitumen sheet, that is, the surface opposed to the surface bearing the adhesive. The presence of the granules in the sheet, while not critical to the operation of the present invention, does provide a roofing surface which is more desirable to the customer.

Application of the Membrane to the Insulation As shown in Figure 2, the rigid spray polyurethane foam insulation 8 which has been applied to the roof deck 3 is now the substratum onto which the self-adherent modified bitumen membrane cap sheet 5 is applied. The pressure sensitive self adhesive 1 can be viewed in Figure 2 and 3. A top view with sections peeled away of this system is displayed in Figure 3. To apply the self-adhering modified bitumen membrane, the release liner is peeled away and the membrane laid in place with the application of pressure to ensure contact. This application of pressure may be assisted by the use of a weighted roller.

Uses of the Present Invention The present invention provides a hybrid composite roofing system which is, in essence, two conventional roofing systems combined into one. This composite system is novel over either traditional roofing system because the polyurethane stratum provides an insulating monolithic seal waterproofing base layer in one step, and the waterproofing layer of self-adhering modified bitumen membrane provides durability, traffic resistance and puncture resistance that PUF roofing lacks by itself. It also provides the UV protection provided by required traditional coatings in PUF roofing. Providing a self-adhering membrane eliminates the use of adhesives at the installation site. Often the use of different adhesives may result in compatability issues, application issues, job and application cleanliness issues, seam issues, etc.

In many applications of the present invention, the sprayed in-place polyurethane foam stratum is a foamed in-place polymeric cellular material with a density of at least 2.2 lbs/ft³ and compressive strength greater than 30 psi. Quite often, depending on roof construction scheduling, the surface of this base waterproofing/insulating layer of polyurethane foam of this composite roofing system will receive a UV protective coating that will not interfere with subsequent application of the self adhering modified bitumen sheet. This will be done in cases where the polyurethane foam will be left unprotected from UV for a period of greater than 24 hours. The top waterproofing layer of self-adhering modified bitumen cap sheet is then applied by setting the roll in place after the release liner on the self adhesive bottom surface of the sheet is removed. Most often the side laps and end laps will be manufactured free of parting agent or material that will prevent or interfere with adhesion of the self adhesive on application the successive modified bitumen sheet in roof construction. These areas free of parting agent will usually have release liner which would have to be removed to allow manufacture. In certain instances, a primer may need to be utilized at side or end laps that have surface materials that would interfere with the self adhesive.

While the present invention has been described according to the best mode known to the inventors, the scope and extent of the invention is not to be measured by the written description, but is instead to be determined by the scope of the claims attached to and made a part hereof.

Claims

CLAIMS What is claimed is:

1. A composite roof structure supported by a roof substrate, comprising: a stratum of foamed-in-place insulation, a lower surface thereof directly adhered to the roof substrate and an upper surface; and a stratum of roofing membrane having a bottom and a top surface, the bottom surface adhered to the upper surface of the insulation by a pressure sensitive adhesive initially disposed on the bottom surface of the membrane.

2. The composite roof structure of claim 1 wherein an intermediate coating of an ultraviolet protectant is interposed between the upper surface of the insulation and the pressure sensitive adhesive.

3. The composite roof structure of claim 1 wherein the roofing membrane is a modified bitumen sheet.

4. The composite roof structure of claim 1 wherein the top surface of the roofing membrane has roofing granules embedded therein.

5. The composite roof structure of claim 1 wherein the pressure sensitive adhesive is asphalt based.

6. The composite roof structure of claim 1 wherein the insulation stratum comprises a polyurethane.

7. The composite roof structure of claim 6 wherein the polyurethane foamed in place from a polyol and a di-isocyanurate.

8. The composite roofing structure of claim 1 wherein the insulation stratum is a closed-cell material with a density of at least about 2.2 pounds per cubic foot and a compressive strength of at least about 30 pound per square inch.

9. A method of installing a roofing system on a building having a substratum prepared for receiving the roofing system, comprising the steps of: applying a stratum of foamed-in-place insulation atop the prepared substratum; allowing the foamed-in-place insulation stratum to achieve a substantial portion of its final cure, as demonstrated by density and compressive strength; and adhering a stratum of roofing membrane having a lower surface provided with a pressure sensitive adhesive predisposed thereon to an upper surface of the cellular insulation.

10. The method of Claim 9, wherein the step of applying the foamed-in-place insulation stratum is followed by the step of applying a coating of a UV protectant on the upper surface of the insulation stratum.