Patent Application
20110265407
The principles disclosed herein relate generally to providing a roofing ventilation system, and more particularly to an above deck roofing ventilation system and related methods of installing a ventilating roofing system.
Conventional roofing absorbs solar energy from the sun and undesirably transfers the heat to the attic. As the sun heats a roof, the sun's radiant energy makes the roof hot. A large portion of this heat travels by conduction through the roofing materials to the attic side of the roof. The hot roof material then radiates its gained heat energy onto the cooler attic surfaces, including the air ducts and the attic floor. As a result, the attic becomes very hot during the day, causing higher interior temperatures and resulting in higher cooling costs. Typical roofing materials can absorb more than 70 percent of the solar energy that falls on them. Roofs having dark roofing materials, which tend to absorb more of the sun's solar energy, may become as hot as 190° F. on a sunny day. Even lighter colored roofing materials (e.g. white or green) can become as hot as 175° F.
Currently, home and building construction encourages the use of attic space to provide ventilation to help remove attic heat in the summer months and moisture from the attic in winter months. In most cases, heat flows through the attic by a combination of conduction, convection, and radiation. Conduction transfers heat from a hotter location within a material or assembly to a colder location. Convection occurs when a liquid or gas is heated by a surface, becomes less dense, and rises (natural convection), or when a moving stream of air absorbs heat from a warmer surface (forced convection). Radiant heat travels away from a surface and heats anything solid that absorbs the incident energy. Radiant heat transfer occurs because warmer surfaces emit more radiation than cooler surfaces.
It is useful, and in many locales a building code requirement, that the attic area of a building be provided with a means to permit air exchange. Cooler air is sucked up into the attic as hot air is vented out through the top of the roof through roof vents, turbine vents, ridge vents, or power ventilator exhaust fans. Ventilation prevents undue heat buildup, which can render the living quarters of the building uncomfortable and impose unreasonable energy requirements for cooling. Proper ventilation of the attic area also tends to preserve the structural integrity of the roof and roof coverings. Some examples of attic vents include roof ridge vents, soffit vents, and gable vents.
In the last few years ventilation studies have shown that attic ventilation may not be advantageous in all climates. The heat generated by the roof causes the attic to get hot, which in turn provides heat load on the cooled building interior spaces. A ventilation system that moves the ventilation from the attic space to where the heat is generated would be beneficial. These principles are described below for removing a significant portion of the heat absorbed by the roof covering before it can be radiated to the attic space.
Disclosed herein are an above deck ventilation system for a roof, and related methods of installation, having a ventilation medium sandwiched between a roof deck and a roof covering providing air channels between the roof deck and the roof covering. In one embodiment, a roofing system is provided, and may comprise a roof deck and a roof covering. In addition, the roofing system may comprise a ventilating medium disposed between the roof deck and the roof covering, where the ventilating medium may have a plurality of open air chambers disposed between a top sheet and the bottom sheet and traversing the length of the ventilation medium.
In one embodiment, a roofing system incorporating the principles disclosed herein may comprise a roof deck, a roof covering, and a ventilating medium. The ventilating medium is disposed between the roof deck and the roof covering, and comprises one or more open air chambers between the roof deck and the roof covering.
In another embodiment, a composition roofing shingle incorporating the principles disclosed herein may comprise a first layer comprising a headlap area, a buttlap area and a common bond area between the headlap and buttlap areas. The first layer has an interior surface and an exterior surface, wherein only the exterior surface of only the buttlap area of the first layer provides at least an initial portion of an exposure surface of the shingle while the exterior surface of the headlap, and common bond areas of the first layer are configured to be overlapped by a portion of a second shingle. In addition, in such an embodiment, the shingle may also comprise a ventilating medium attached to the first layer at a top edge of the headlap area that is opposite its common bond area, and extending across the headlap area of the shingle. In such embodiments, the ventilating medium comprises one or more open air chambers between the roof deck and the roof covering.
In other aspects, methods of installing a ventilated roof are also disclosed. In one embodiment, such a method may comprise preparing a roof deck of a structure, which may include placing a roofing membrane on the roofing deck to help seal the deck. The method could then include placing a ventilating medium on the roof deck, wherein the ventilating medium comprises one or more open air chambers such as those discussed above. Then the method could include affixing roof coverings to a top surface of the ventilating medium. Moreover, such a method may include placing the roofing membrane on the ventilating medium, and the roof coverings on the membrane. Still further, the installation method could include placing a roofing membrane both above and below the ventilating medium.
In accordance with the disclosed principles, an above deck ventilation system is provided, see
The roof covering 30 may be shingles or similar exterior building materials and are secured to the roof deck 20 to finish sloping portions of the roof 100 in accordance with conventional construction practices. The roof covering 30 may be shingles or roll roofing. Shingles and roll roofing are designed to withstand exposure to weather and the elements. In some embodiments, the roof covering may be, but is not limited to, asphalt shingles, metal shingles, polymer based shingles, wood shingles, cement tile shingles, clay tile shingles or any suitable roof covering. Asphalt shingles and roll roofing generally contain the same basic components which provide protection and long term wear associated with asphalt roofing products. Asphalt shingles are typically manufactured as strip or three tab shingles, laminated shingles, interlocking shingles, and large individual shingles in a variety of weights and colors. Asphalt shingles may include an organic felt or fiberglass mat base on which an asphalt coating is applied. The organic felt or fiberglass mat base gives the asphalt shingle the strength to withstand manufacturing, handling, installation and servicing activities, and the asphalt coating provides resistance to weathering and stability under temperature extremes. An outer layer of mineral granules is also commonly applied to the asphalt coating to form a weather surface which shields the asphalt coating from the sun's rays, adds color to the final product, and provides additional fire resistance.
In some embodiments, the ventilating medium 40 has a bottom sheet 24 for engaging a surface of the roof deck 20, a top sheet 26 for engaging the roof covering 30, and sides 28 that form longitudinally-extending side edges of the ventilating medium 40. Moreover, the upper and/or lower surfaces of the ventilating medium 40 may include means for hold the ventilating medium 40 to the roof deck, and/or a mechanism for helping to hold the roof coverings to the top of the ventilating medium 40. For example, the ventilating medium 40 may comprise protrusions extending on the upper and/or lower surfaces. In other embodiments, the ventilating medium 40 may include adhesive on its upper and/or lower surfaces. Of course any such mechanism may be employed on the ventilating medium 40.
A plurality of cell walls 23 are provided between the top sheet 26, the bottom sheet 24 and sides 28 in fixed positions. The cell walls 23 form cells 22 creating paths of ventilation extending longitudinally from a first end 32 of the ventilating medium 40 to a second opposing end 34. The cells 22 are sandwiched between the top sheet 26 and bottom sheet 24 and sides 28. The cells 22 provide an insulating space generally containing air. In some embodiments, the cell walls 23 can be made of an air impermeable material, such as plastic, cardboard, metal, or the like, or of an air permeable material. If an air impermeable material is utilized, perforations can be made through the cells 22 to provide ventilation passageways. Alternatively, the cell walls 23 can be provided as discontinuous, spaced-apart strips that provide a path of ventilation there between. Permeable cell walls 23 can include those made of a plastic or metal mesh material or fabric material such as a non-wicking hydrophobic material or a non-woven fabric. Preferably, the permeable cell wall 23 materials provide a multiplicity of closely spaced openings permitting a flow of air therethrough, but preventing the infiltration of weather, insects and the like.
In some embodiments, the cells 22 are located in side-by-side relation. In other embodiments, the cells 22 are located in a two layer stacked relation (double wall), one on top of the other. In some embodiments, the cells 22 may be formed in a regular array or in an irregular array. The shape of the separate cells 22 or cavities of the ventilation medium 40 may be of any shape, including for instance, square (see
The ventilating medium 40 is of sufficient thickness to allow the heat from the roof covering 30 to be transferred by air out of the roof 100 without the heat being radiated into the attic space. In some embodiments, the height of the ventilating medium 40 ranges from about 0.5 inches to about 4 inches, more preferably from about 0.75 inches to about 2 inches. In a preferred embodiment, the ventilating medium 40 is a panel having a width ranging from about 1 to about 8 feet, more preferably 4 feet and a length ranging from about 1 to about 24 feet long, more preferably about 8 feet. If sold in panels, the ventilating medium 40 preferably is sold in standard construction sizes. In other embodiments, the ventilating medium 40 may be sold in a roll form. In some embodiments, the ventilating medium 40 has an R-value (an indication of it's resistance to heat flow) ranging from about R1 to about R10, more preferably from about R2 to about R5.
The ventilating medium 40 should not affect the fire resistance performance of the roof covering 30. The roof covering preferably meets the UL790 and/or ASTM E108 roofing fire performance standards. The ventilating medium 40 may be made out of any material with sufficient strength to support a roof covering in all kinds of weather conditions such as: polyethylene, ultra-high molecular weight polyethylene (UHMWPE); high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene, low-impact polystyrene, high-impact polystyrene, acetal, polyvinyl chloride (PVC), (poly-)acrylonitrile-butadiene-styrene (ABS), polyamide, polyester, polycarbonate, (poly-)styrene-butadiene-styrene (SBS), (poly-)styrene-butadiene-rubber (SBR), styrene-olefin block polymers (SEBC), acrylic, nylon, polyether imide (PEI), polyurethane and or any other suitable thermoplastic or thermoset plastic. Rigid cellulosic reinforced plastic or similar materials may also be used. In some embodiments, the ventilating medium 40 has a composite strength in compression sufficient to support the overlying roof covering 40.
In some embodiments, the ventilating medium 40 may be multi-wall polycarbonate panels used in the construction of greenhouses, such as those sold under the name Unitrex® SUNLITE manufactured by H & F Manufacturing, Solexx™ manufactured by Adaptive Plastics Inc., or Lexan® manufactured by G.E. Plastics.
The illustrated exemplary shingle 100 includes a first shingle layer 110 providing the overall length and width of the shingle 100. Although a single layer shingle 100 is illustrated, any type of shingle may be employed with the disclosed principles, such as double layer strip shingles, or three-layer composite shingles. In addition, the term “layer” as used here does not necessarily mean that each layer is manufactured separately and later adhered together. Instead, the shingle 100 may be of a single final piece, manufactured of first and second laminate layers (or even more) making the shingle 100 appear as if it is distinct adhered layers.
The shingle 100 includes the buttlap area 130 and headlap area 150 mentioned above, as well as the common bond area 140 of the shingle 100 between these two areas. As a result, the first shingle layer 110 includes the buttlap area 130, the common bond area 140, and the headlap area 150 of the shingle 100. The exterior surface of the first shingle layer 110 provides a large portion of the exterior surface of the shingle 100, and typically includes predetermined decorative shapes cut into the buttlap area 130.
In addition, the exemplary shingle 100 also includes the ventilating medium 40 located in the headlap area 150, adjacent to the common bond area 140 on the interior surface of the first shingle layer 110. In accordance with the disclosed principles, the ventilating medium 40 may be adhered to the headlap area 150. In addition, however, the ventilating medium 40 may alternatively be formed into and/or as part of the first shingle layer 110. Providing the ventilating medium 40 to the back of an asphalt shingle provides resistance to the thermal transfer of heat from the shingle to the roofing deck, which when then be transferred to the building's attic space. As is well known, lower attic temperatures reduce the load on air-conditioning equipment, which in turn reduces overall utility costs for the building.
In an exemplary embodiment, the ventilating medium 40 is provided in sheet form, and is adhered to the backside of an asphalt shingle 100 headlap area 150 starting at a top edge of the headlap area 150 that is opposite its common bond area 140 (typically the nail zone for shingle installation), and extending across the headlap area 150 an amount substantially equal to the exposure surface of the shingle 100. For example, such a ventilating medium 40 could be from just a few millimeters thick to 1″ or more thick depending on the shingle design an desired application. Of course, any advantageous ventilation thickness may be employed, for example, up to several inches thick if desired. Accordingly, no limitation to any particular thickness is intended or should be implied.
Still further, in some embodiments, a roofing membrane may also be incorporated into a roofing system or method of installation in accordance with the disclosed principles. For example, a roofing membrane may be placed directly on the roof deck, and then the ventilating medium placed on top of the roofing membrane. Alternatively, a roofing membrane may be placed directly on the ventilating medium, and then the roof coverings placed on top of the roofing membrane. In still other embodiments, a membrane may be used on both sides of the ventilating medium 40.
As in other embodiments discussed above, the shingles 100a, 100b in
In advantageous embodiments of the disclosed shingles 100a, 100b, the length of the ventilating medium 40a, 40b from the top edge opposite the common bond area should typically not be more than 0.5 inch less than the shingle's final exposure after the roof installation is complete (i.e., with the overlap of other installed shingles). With this shingle design and overlay during installation, the ventilating medium 40a, 40b will substantially abut each from shingle to shingle, thereby allowing the ventilating chambers, which are oriented from the top edge of the shingle down to the common bond area, to align in order to allow ventilation from shingle to shingle across the roof deck 20. In this manner, the ventilating medium 40a, 40b will completely cover the roof deck 20, and thereby increases the insulation R-value of the overall shingled roof. It should be noted that the shingles 100a, 100b illustrated in
Moreover, ventilating medium 40a provided at substantially the same width as the shingles' 100a, 100b exposure surface also allows shingle sealant to be kept uncovered while being stored in the bundle before application. This sealant is typically present on the bottom surface of the second shingle 100b (i.e., the underside of the buttlap area of shingle 100b) to allow its adherence to the exposed headlap surface of the shingle 100a below it. Thus, the ventilating medium 40a, 40b present on the back/underside of the headlap area above the common bond area still allows the upper shingle 100b to be applied and fastened in a normal fashion over the lower shingle 100a. Thus, the ventilating medium 40a, 40b does not interfere with the fastening area or the shingles 100a, 100b sealing to one another after installation. Even further, the ventilating medium 40a, 40b itself may include an adhesive or other sealant, which may also be used to adhere the shingles 100a, 100b to the roof deck 20.
To simulate a ventilated attic, two (2) 2′×2′ roof decks were constructed at 1:1 slope, with fully enclosed attic spaces insulated on all sides with RU20 foam board. Slots, approximately 1″, were cut at the eave and ridge of the attic to simulate attic ventilation. One roof deck was outfitted with black asphalt shingles applied directly to deck. On the other roof deck to simulate a deck having the disclosed invention, a ventilating medium 40 was installed directly to the deck with the black asphalt shingles applied on top of the ventilating medium 40. The ventilating medium 40 was 1″ (25 mm) thick clear Unitrex® Polycarbonate SUNLITE panels from H & F Manufacturing (www.hfmfgcorp.com). Thermocouples were placed at the following locations of both decks: a) shingle surface; b) roof deck surface (exterior); c) roof deck surface (interior; attic space); and d) center of attic space. A final thermocouple was placed to measure ambient temperatures. The roof decks were exposed to daytime climate conditions by situating the roof decks in an orientation to maximize sun exposure. For these simulated ventilated attics, one with a ventilating medium 40 and one without, data was collected at 10 minute intervals for several days. See
To simulate a non-ventilated attic, the same two (2) 2′×2′ roof decks discussed above had the attic ventilation openings blocked. The roof decks were again exposed to daytime climate conditions by situating the roof decks in an orientation to maximize sun exposure. For these simulated attics with no ventilation, one deck with a ventilating medium 40 and one without, data was collected at 10 minute intervals for several days. See
After reviewing the data gathered using the examples set forth above, and in accordance with the disclosed principles, the data revealed that the ventilating medium 40 removes a significant portion of the heat absorbed by the roof covering 30 before it is radiated into the attic. Importantly, the ventilating medium 40 has reduced the temperature at all areas of the roof and attic. Furthermore, this was the case whether the attic itself was ventilated or not. In some embodiments, the thickness of the ventilating medium 40, color of the roof covering 30 and type of roof covering 30 may determine the amount of heat reduction in the attic space
While various embodiments in accordance with the disclosed principles have been described above, it should be understood that they have been presented by way of example only, and are not limiting. Thus, the breadth and scope of the invention(s) should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the claims and their equivalents issuing from this disclosure. Furthermore, the above advantages and features are provided in described embodiments, but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages.
Additionally, the section headings herein are provided for consistency with the suggestions under 37 C.F.R. 1.77 or otherwise to provide organizational cues. These headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure. Specifically, a description of a technology in the “Background” is not to be construed as an admission that technology is prior art to any invention(s) in this disclosure. Neither is the “Summary” to be considered as a characterization of the invention(s) set forth in issued claims. Furthermore, any reference in this disclosure to “invention” in the singular should not be used to argue that there is only a single point of novelty in this disclosure. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby. In all instances, the scope of such claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings herein.
