Technical field

The invention relates generally to the field of roofing and decking assemblies used in the field of construction. Particularly, aspects of the invention relate to wind vented roof systems comprising a thermally insulated metal deck, a roofing membrane, and pressure equalizing vents to hold the membrane in place.

Background

Outer exterior surfaces of buildings must be protected from environmental forces such as wind and rain. Roofing membranes composed of polymeric materials are used for waterproofing of flat or slightly sloped roofs whereas sloped roofs are typically covered with roof shingles. Low-slope roof assemblies are typically composed of a roofing membrane, a rigid insulation and/or cover board, and a roof deck. The roofing membrane is typically applied directly on the top of the insulation board, which is used to improve the thermal insulation properties of the roof assembly. Alternatively, the roofing membrane can be secured to a cover board, which is applied on top of the insulation board. In ventilated and cold roof designs, the insulation board can also be located below the roof deck.

Commonly used materials for the roofing membranes include plastics, in particular thermoplastics such as plasticized polyvinylchloride (p-PVC), thermoplastic olefins (TPE-O, TPO), and elastomers such as ethylenepropylene diene monomer (EPDM). The roofing membranes are typically delivered to a construction site in form of rolls, transferred to the place of installation, unrolled, and adhered to the substrate to be waterproofed. Roofing membranes must be securely fastened to the roof substrate to provide sufficient mechanical strength to resist the shearing forces applied on it due to high wind loads. In a mechanically attached roof system, the roofing membrane is fastened to the roof substrate by using screws and/or barbed plates. In fully adhered roof systems, the roofing membrane is adhered to the roof substrate indirectly by using an adhesive composition, such as a solvent- or water-based contact adhesive. In ballasted roof systems, the roofing membrane is not anchored or adhesively adhered to the roof substrate but “ballasted” with a stone material, typically gravel. Mechanical fastening enables high strength bonding, but it provides direct attachment to the roof substrate only at locations where a mechanical fastener affixes the membrane to the surface, which makes mechanically attached membranes susceptible to flutter. Using adhesives to adhere the membrane increases the installation costs and there is a growing concern over volatile organic compounds (VOCs) contained in solvent-based adhesives being released into the environment during installation of the roofing membrane. Water-based adhesives may be preferred in terms of environmental aspects, but their use is practically restricted to temperatures of 5 °C and above. Fully adhered membrane systems are also difficult to recycle due to the different materials used in the adhesives and membranes. Ballasted roofs are relatively inexpensive, but the weight added to the building can be a concern in some cases.

Use of pressure equalizing vents to hold the roofing membrane in place provides an alternative to the mechanically fastened, fully adhered, and ballasted roof systems. These types of roof systems are also known as “vented roofs”. US 4223486 discloses use of pressure equalization system for automatically transferring vacuum uplift forces on the top side of a loose laid roofing membrane covering a plurality of insulation blocks to the underneath side of the roofing membrane. The system comprises a plurality of one-way valves in communication with a space between a lower surface of the roofing membrane and an upper surface of insulation blocks, which valves can equalize the positive air pressure between the loose laid membrane and the insulation blocks with the under pressure that occurs on the top of the roofing membrane when wind is blowing across the roof. The one-way valves are thus able to prevent uplift of the roofing membrane. Another patent US 4608792 discloses a vented roof using a suction device driven by wind or electrical motors or a combination of both to create a vacuum in the space between the roof substrate and the roofing membrane, which is causes the membrane to be held in place.

A vented roof system based on the use of an air conduit and suction means requires that the space between the insulation layer and the roofing membrane is airtight. In traditional metal deck roof systems, such as the one disclosed in US 5584153, the insulation layer is mechanically fastened to peaks of a corrugated metal sheet by using screws that penetrate through the whole assembly into the metal sheet, which is anchored to a roof beam. The seams formed between longitudinal edges of the adjacent insulation panels are not sealed and, therefore, no airtight space is created between the roofing membrane and the insulation layer. For the above discussed reasons, the use of pressure equalizing vents to hold a loose laird roofing membrane in place in an insulated metal deck roof system has not been possible.

It would be desirable to provide a metal deck roof system that enables the use of pressure equalizing vents to hold a loose laid roofing membrane which at least partially eliminates the use of mechanical and adhesive bonding means. The novel type of metal deck roof system would preferably also enable easier installation with reduced costs compared vented roof systems of prior art.

Summary

In embodiments, an object of the present invention is to provide a vented roof system comprising a thermally insulated metal deck covered with a roofing membrane. Another object of the present invention is to provide a vented roof system that enables fast installation and improved recycling of the roofing membrane.

Embodiments of the invention are directed to a roof system that includes a roof framework, a plurality of roof panels, a roofing membrane covering at least a portion of an upper major surface of the roof panels, and at least one roof vent that is capable of equalizing pressure beneath the roofing membrane. Each roof panel of the roof system includes an insulation layer that is arranged between inner and outer skins.

It was surprisingly found out that roof panels comprising an insulation layer bonded between inner and outer skins and longitudinal edges, wherein the roof panels are designed in such a manner that two panels can be connected to one another by a form-fit connection, enable providing a roof system where an airtight space is formed between the roofing membrane and the roof panels. Furthermore, the presence of an air-tight space between the roofing membrane and the roof panels enables the use of pressure equalization vents to hold the roofing membranes in place.

One of the advantages of the roof system in embodiments of the present invention is that the roofing membrane can be easily recycled since no adhesives have been used to bond the membrane to the roof structure.

Another advantage is that the use of roof panels with inner and outer skins eliminates installation of multiple layers and the involved labor.

Brief Description of the Drawings

Fig. 1 shows a cross-section of a vented roof system comprising a roof framework (2), a plurality of roof panels (3), a roofing membrane (4) covering the upper major surface of the roof panels (3), and a plurality of roof vents (5) installed on the upper major surface of the roof panels (3). Fig. 2 shows a cross-section of a roof panel (3) comprising an insulation layer (6) arranged between inner and outer skins (7, 8) and longitudinal edges (9, 10) with a tongue and groove configuration.

Detailed Description

This disclosure is directed to a roof system that includes: i. A roof framework (2), ii. A plurality of roof panels (3), iii. A roofing membrane (4) covering at least a portion of an upper major surface of the roof panels (3), and iv. At least one roof vent (5) capable of equalizing pressure beneath the roofing membrane (4), wherein each roof panel (3) comprises an insulation layer (6) arranged between inner and outer skins (7, 8).

Substance names beginning with "poly" designate substances which formally contain, per molecule, two or more of the functional groups occurring in their names. For instance, a polyol refers to a compound having at least two hydroxyl groups. A polyether refers to a compound having at least two ether groups.

The term “polymer” designates a collective of chemically uniform macromolecules produced by a polyreaction (polymerization, polyaddition, polycondensation) where the macromolecules differ with respect to their degree of polymerization, molecular weight and chain length. The term also comprises derivatives of said collective of macromolecules resulting from polyreactions, that is, compounds which are obtained by reactions such as, for example, additions or substitutions, of functional groups in predetermined macromolecules and which may be chemically uniform or chemically non- uniform.

The term “molecular weight” refers to the molar mass (g/mol) of a molecule or a part of a molecule, also referred to as “moiety”. The term “average molecular weight” refers to number average molecular weight (Mn) of an oligomeric or polymeric mixture of molecules or moieties. The molecular weight may be determined by gel permeation chromatography (GPC) using polystyrene as standard, using styrene-divinylbenzene gel with porosity of 100 Angstrom, 1000 Angstrom and 10000 Angstrom as columns and, depending on the molecule, tetrahydrofurane as a solvent, at 35°C, or 1 ,2,4-trichlorobenzene as a solvent, at 160 °C.

The term “melting temperature” refers to a temperature at which a material undergoes transition from the solid to the liquid state. The melting temperature (Tm) is determined by differential scanning calorimetry (DSC) according to ISO 11357-3 standard using a heating rate of 2 °C/min. The measurements can be performed with a Mettler Toledo DSC 3+ device and the Tm values can be determined from the measured DSC-curve with the help of the DSC-software. In case the measured DSC-curve shows several peak temperatures, the first peak temperature coming from the lower temperature side in the thermogram is taken as the melting temperature (Tm).

The term “glass transition temperature” (T _g ) refers to the temperature above which temperature a polymer component becomes soft and pliable, and below which it becomes hard and glassy. The glass transition temperature (T _g ) is determined by dynamical mechanical analysis (DMA) as the peak of the measured loss modulus (G”) curve using an applied frequency of 1 Hz and a strain level of 0.1 %.

The “amount or content of at least one component X” in a composition, for example “the amount of the at least one acrylic polymer AP” refers to the sum of the individual amounts of all acrylic polymers AP contained in the composition. Furthermore, in case the composition comprises 20 wt.-% of at least one acrylic polymer AP, the sum of the amounts of all acrylic polymers AP contained in the composition equals 20 wt.-%.

The term “layer” refers in the present disclosure to a sheet-like element having upper and lower major surfaces, i.e., top and bottom surfaces, defining a thickness of the layer therebetween. A layer can have a length and width of at least 5 times, at least 15 times, or even at least 25 times, greater than the thickness of the layer.

The term “room temperature” designates a temperature of 23 °C.

In embodiments, the roof system of the present invention includes a plurality of roof panels comprising an insulation layer arranged between and bonding with inner and outer skins.

In some aspects, the roof panels can be designed in such a manner that two panels can be connected to one another by a form-fit connection to enable providing a roof system where an airtight space is formed between the roofing membrane and the roof panels. The term “form-fit connection” generally refers to a connection between two or more components via mechanical interlocking.

In some embodiments, each roof panel has longitudinal edges with a tongue and groove configuration to enable mating of adjacent roof panels along their longitudinal edges. Examples of roof panels with this type of mating are described in U.S. Patent No. 11 ,299,889, which is incorporated by reference herein.

According to one or more embodiments, at least one of the longitudinal edges of each roof panel has at least one groove comprising a sealant to ensure an air- and vapor-tight connection between mated roof panels. The composition of the sealant is not particularly restricted. Any type of conventional sealant materials including, for example, butyl rubber-, epoxide-, polyurethane-, and silicone-based sealants can be used, particularly butyl rubber-, polyurethane-, and silicone-based sealants.

According to one or more embodiments, the inner and outer skins of the roof panels are metal sheets, such as aluminum or steel sheets.

In some embodiments, the skins can have a thickness of 0.05 - 10 mm, 0.1 - 5 mm, or 0.15 - 3.5 mm.

The roofing membrane can be adhesively or mechanically secured to the primary exterior surface of the plurality of roof panels to provide a waterproof seal to the roof system. According to one or more embodiments, the roofing membrane is adhesively or mechanically secured to the outer skin of the plurality of roof panels.

According to one or more embodiments, the roof panels are mechanically and/or adhesively secured to a frame or truss forming the roof framework.

In such construction, the roof panels are directly secured to the roof framework forming an insulated roof deck without use of additional layers, such as a corrugated metal sheet. The structure reduces the number of individual layers installed on the roof and consequently reduces installation time and involved labor.

According to one or more embodiments, the roof system further comprises a vapor barrier arranged between the roof framework and the plurality of roof panels.

Such vapor barriers are known to a person skilled in the art in the field of roofing. These types of membranes are installed below an insulation layer and used to prevent water vapor from getting into a wall from the inside of the building structure. A vapor barrier typically has a Sd value of > 10 m or even > 100 m, wherein the Sd value refers to the equivalent air layer thickness measured according to ISO 12572 standard.

In some embodiments, the insulation layer of the roof panel is a foam panel having a closed cell structure. Suitable foam panels having a closed cell structure include, for example, molded expanded polystyrene (EPS) foam panels, extruded expanded polystyrene (XPS) foam panels, polyurethane foam panels (PUR), and polyisocyanurate (PIR) foam panels.

In embodiments, the foam panel can have a thickness determined by using the measurement method as defined in DIN EN 1849-2 standard of 5 - 500 mm, 10 - 350 mm, or 25 - 150 mm.

According to one or more embodiments, the foam panel is selected from a group consisting of molded expanded polystyrene (EPS) foam panel, an extruded expanded polystyrene (XPS) foam panel, a polyurethane foam panel (PUR), or a polyisocyanurate (PIR) foam panel. In embodiments, the foam panel can have a density of 10 - 150 g/l, 15 - 100 g/l, or 25 - 75 g/l.

According to one or more embodiments, the roof system comprises a first plurality of fasteners securing the adjacent roof panels together along the longitudinal edges and a second plurality of fasteners securing the plurality of roof panels directly to and only to a frame or truss forming the roof framework.

The first plurality of fasteners secures the adjacent roof panels together with one another along the longitudinal edges. The first plurality of fasteners can be spaced from one another along the longitudinal edges at a distance apart from about four to 10 inches on center.

The second plurality of fasteners are spaced from each other, transverse to the longitudinal axis, at a distance apart from one another of about four to 10 inches on center. A plurality of washers can be positioned on each of the second plurality of fasteners. The plurality of washers can have a diameter of about a half inch to three inches, for example.

According to one or more embodiments, the roof system further comprises a third plurality of fasteners securing the longitudinal edges of each of the plurality of the roof panels directly to and only to a frame or truss forming the roof framework, and in some aspects the third plurality of fasteners can be aligned with the second plurality of fasteners.

The third plurality of fasteners is in line with the second plurality of fasteners, thus, transverse to the longitudinal axis. The washers may have a circular or polygonal configuration.

The roof system further comprises at least one roof vent configured to equalize pressure beneath the roofing membrane.

Generally, any type of vent capable of equalizing wind uplift pressure is suitable for use in the present invention.

In embodiments, each roof vent comprises at least one air conduit interposed between the upper major surface of the roof panels and the lower major surface of the roofing membrane for permitting flow of gas in a space between the plurality of roof panels and roofing the membrane, and a suction mechanism operably connected to said air conduit for withdrawing air from said air conduit thereby reducing the pressure between said roofing membrane and said plurality of roof panels and creating a hold down force on said roofing membrane.

In embodiments, the suction mechanism can be selected from a wind driven rotatable turbine, a wind operated venturi, and a powered air moving device.

Suitable roof vents comprising an air conduit and suctions mechanism are commercially available, for example, under the trade name of VADA vent from VADA LLC; under the trade name of VT2 vent from VT Technology; and from Windsmart under the trade name of Windforce 365 vent. Suitable vents are also disclosed in U.S. Patent No. 10,571 ,139, which is incorporated by reference herein.

The VADA vent is based on use of a ‘whirlybird' turbine, which derives power from wind blowing in any direction. The turbine spins a series of fans in the duct beneath the turbine, which actively pull air from beneath the membrane. By creating a negative differential pressure underneath the membrane, compared with atmospheric pressure above it, the vent ensures that the membrane stays attached to the surface. The V2T and Windforce 365 vents, unlike the “whirlybird” turbine vent, rely on the Venturi effect to create negative pressure, rather than moving parts.

There are some differences in effectiveness between the three above discussed vents at equalizing pressure under the roofing membrane but, in principle any of the commercially available vents can be used in connection with the roof system described herein.

According to one or more embodiments, the at least one roof vent is a modular roof vent comprising a base, a cup arranged in the base, a flexible membrane arranged in the cup, an airflow guide arranged on the base and the cup, and a cover on the air flow guide. The flexible membrane can allow air to flow through the vent when the pressure outside of the vent is less than the pressure inside the base and prevents air from flowing through the vent when the pressure outside of the vent is greater than pressure inside the base.

According to one or more embodiments, the at least one roof vent is a modular roof vent comprising a base having an internal shoulder spaced apart from a top of the base, a support cup on the internal shoulder and laterally restrained by the base, the support cup having a plurality of apertures at a base of the support cup to allow air to flow therethrough, a flexible membrane on the base of the support cup, an airflow guide on the base, and a cover on air flow guide, wherein the airflow guide can be attached to the base by at least one removable fastener. In some aspects, the flexible membrane can be supported so that is free to flex towards the airflow guide to allow air to flow from the base through the airflow guide but is prevented from flexing towards a bottom of the base to prevent air from flowing towards a bottom of the base, and wherein the internal shoulder prevents the support cup from moving towards a bottom of the base.

Such modular roof vents have the advantage that the parts of a vent are easily removable from another, which enables conducting modifications to the roof without having to remove the whole vent. Furthermore, the structure of the base allows a technician to effectively pass tools through the base to modify the roof, which means that the whole vent does not have to be removed in case only a portion of the roof under the vent must be modified.

According to one or more embodiments, the roof system comprises a first low wind load area where the roofing membrane is loose laid over the plurality of roof panels and a second high wind load area where the roofing membrane is mechanically or adhesively adhered to the plurality of roof panels, wherein the roof vents are installed only in the first low wind area.

The high wind load area can include at least zones at the corners and the perimeter of a roof.

The roofing membrane can be a single- or multi-ply-membrane. The term “single-ply membrane” designates in the present disclosure membranes comprising one single waterproofing layer whereas the term “multi-ply membrane refers to membranes comprising more than one waterproofing layer having same or different compositions. Single- and multi-ply membranes are known to a person skilled in the art and they may be produced by any conventional means, such as by way of extrusion or co-extrusion, calendaring, or by spread coating. According to one or more embodiments, the roofing membrane is a single-ply roofing membrane.

Suitable materials for the roofing membrane include plastics, such as plasticized polyvinylchloride (p-PVC), thermoplastic olefins (TPE-O, TPO), elastomers such as ethylene-propylene diene monomer (EPDM), and bitumen.

According to one or more embodiments, the roofing membrane comprises at least one waterproofing layer comprising at least 25 wt.-%, at least 35 wt.-%, at least 50 wt.-%, or at least 65 wt.-%, based on the total weight of the waterproofing layer, of at least one polymer selected from polyvinylchloride (PVC) resin, polyolefin, halogenated polyolefin, rubber, and ketone ethylene ester (KEE).

Suitable PVC resins for use as the at least one polymer include ones having a K-value determined by using the method as described in ISO 1628-2-1998 standard in the range of 50 - 85 or 65 - 75. The K-value is a measure of the polymerization grade of the PVC-resin and it is determined from the viscosity values of the PVC homopolymer as virgin resin, dissolved in cyclohexanone at 30° C.

Term "polyolefin" refers in the present disclosure to homopolymers and copolymers obtained by polymerization of olefins. Suitable polyolefins for use as the at least one polymer include, for example, thermoplastic polyolefins (TPO) and polyolefin elastomers (POE).

Especially suitable polyolefins include heterophasic propylene copolymers. These are heterophasic polymer systems comprising a high crystallinity base polyolefin and a low-crystallinity or amorphous polyolefin modifier. The heterophasic phase morphology consists of a matrix phase composed primarily of the base polyolefin and a dispersed phase composed primarily of the polyolefin modifier. Suitable commercially available heterophasic propylene copolymers include reactor blends of the base polyolefin and the polyolefin modifier, also known as “in-situ TPOs” or “reactor TPOs or “impact copolymers (ICP)”, which are typically produced in a sequential polymerization process, wherein the components of the matrix phase are produced in a first reactor and transferred to a second reactor, where the components of the dispersed phase are produced and incorporated as domains in the matrix phase. Heterophasic propylene copolymers comprising polypropylene homopolymer as the base polymer are often referred to as “heterophasic propylene copolymers (HECO)” whereas heterophasic propylene copolymers comprising polypropylene random copolymer as the base polymer are often referred to as “heterophasic propylene random copolymers (RAHECO)”. The term “heterophasic propylene copolymer” encompasses in the present disclosure both the HECO and RAHECO types of the heterophasic propylene copolymers.

Further suitable polyolefins include propylene homopolymers, for example, isotactic polypropylene (iPP), syndiotactic polypropylene (sPP), and homopolymer polypropylene (hPP), and propylene copolymers, especially propylene-a-olefin copolymers. Ethylene copolymers, for example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE), and ethylene copolymers, particularly ethylene- a-olefin copolymers, may also be suitable for us as the at least one polymer.

Suitable rubbers for use as the at least one polymer include, for example, styrene-butadiene rubber (SBR), ethylene propylene diene monomer (EPDM) rubber, butyl rubber, polyisoprene, polybutadiene, natural rubber, polychloroprene rubber, ethylene-propylene rubber (EPR), nitrile rubber, acrylic rubber, ethylene vinyl acetate rubber, and silicone rubber, and chemically crosslinked versions of the aforementioned rubbers.

The thickness of the roofing membrane is not particularly restricted, and it depends mainly on the material of the waterproofing layer as well as on the number of waterproofing layers in the roofing membrane. According to one or more embodiments, the roofing membrane has a thickness determined by using the measurement method as defined in DIN EN 1849-2 standard of 0.25 - 5 mm, 0.5 - 4.5 mm, 1 - 3 mm, or 1 - 2.5 mm.

In other aspects, the present invention is directed to a method for providing a roof system as described above including steps of:

I) Providing a roof framework,

II) Installing a plurality of roof panels to the roof framework,

III) Covering the plurality roof panels with a roofing membrane, and

IV) Installing a at least one roof vent capable of equalizing pressure beneath the roofing membrane, wherein each roof panel comprises an insulation layer arranged between inner and outer skins.

In some embodiments, the roof panels can be designed in such a manner that two panels can be connected to one another by a form-fit connection to enable providing a roof system where an airtight space is formed between the roofing membrane and the roof panels.

In some aspects, each roof panel has longitudinal edges with a tongue and groove configuration to enable mating of adjacent roof panels along their longitudinal edges.

According to one or more embodiments, at least one of the longitudinal edges of each roof panel has at least one groove comprising a sealant to ensure an air- and vapor-tight connection between mated roof panels.

According to one or more embodiments, the method comprises a further step of installing a vapor barrier to the roof framework before conducing step II) of the method. According to one or more embodiments, the roof frame comprises a first low wind load area where the roofing membrane is loose laid over the plurality of roof panels and a second high wind load area where the roofing membrane is mechanically or adhesively adhered to the plurality of roof panels, wherein the roof vent(s) are installed only in the first low wind area.