Patent Application
20070294976
As schematically shown in
The spray applied building construction coating material of the subject invention is a water-based elastomeric emulsion, such as but not limited to a water-based acrylic emulsion or an oil-based elastomeric emulsion, such as but not limited to a rubberized (elastomeric) emulsion. For many applications, the spray applied elastomeric building construction coating material of the subject invention is formulated or includes additives to cause a building wrap coating layer 22 formed with the spray applied building construction coating material to have an exposed surface 26 that is sufficiently textured to form moisture drainage and air flow passages for preventing or greatly reducing the accumulation and pooling of water between the textured surface 26 of the building wrap layer and the exterior cladding layer. The elastomeric emulsions forming these coating materials may include fillers to reduce product costs or enhance the performance of the coating emulsions, such as but not limited to chopped glass fibers, chopped plastic fibers, cellulose fibers, small nodules of glass, plastic, or cellulose fibers, or mixtures of one or more of these fibers, that can: a) function as a reinforcement and spanning material to facilitate the bridging of gaps with the spray applied elastomeric building construction coating material; and/or b) contribute to the formation of a textured surface on the building wrap coating layer formed with the coating material. At least some fillers can be incorporated into the emulsions as part of the elastomeric elastomeric coating material prior to spraying the elastomeric coating material. Other fillers, such as but not limited to chopped glass fibers, other chopped fibers, or small nodules of fibers can be sprayed concurrently with the elastomeric coating material and mixed with the elastomeric coating material as the coating material and the chopped fibers are applied to the surface of the sheathing layer to form an elastomeric coating layer reinforced with the chopped fibers.
In a first preferred embodiment of the spray applied elastomeric building construction coating material for forming building wrap layers with textured surfaces, the spray applied elastomeric building construction coating material is formulated so that, after being spray applied onto sheathing, the coating material comprises an exterior portion that forms the exterior facing surface of the coating material, an inner portion that is in contact with and adhered to the sheathing, and an intermediate portion between the exterior portion and the inner portion of the coating material. The composition of the spray applied elastomeric building construction coating material causes the exterior portion of the coating material to solidify at a different and faster rate than the rates at which the intermediate portion and the inner portion of the coating material solidify to form wrinkles in the exterior facing surface of the exterior portion of the coating material and the exterior facing textured surface 26 of the building wrap coating layer 22. When using an oil-based elastomeric emulsion as the coating material, tung oil may be included in the emulsion to cause the intermediate and inner portions of the coating material to dry or solidify at rates sufficiently slower than the rate at which the exterior portion of the coating material dries or solidifies to form a coating layer with a wrinkled, textured surface.
In a second preferred embodiment of the spray applied elastomeric building construction coating material for forming building wrap layers with textured surfaces, the spray applied elastomeric building construction coating material includes one or more particulate additives of particles that have an average size or diameter sufficiently large to form the exterior facing, textured surface 26 of the building wrap coating layer 22. Examples of particulate additives that may be used to create a textured surface on the building wrap coating layer are granules or glass spheres ranging from about 200 to about 600 micrometers in diameter, expanded polystyrene beads or bits ranging from at least 200 micrometers to more than 2500 micrometers (about 0.1 inches at their maximum dimension or diameter), fibrous nodules, and microcapsules of phase change material that typically are about 2 to 100 micrometers in diameter. These textured surface-generating additives can be mixed with the liquid spray emulsion of the coating material or added to the coating material as a separate concurrently applied spray.
In a third preferred embodiment of the spray applied elastomeric building construction coating material for forming building wrap layers with textured surfaces, the viscosity and thixotropy of the coating material can be adjusted so that the coating material can be sputter or splatter sprayed onto the exterior sheathing surface, in a fashion similar to a spray on wall board texture, to create a textured surface on the building wrap coating layer formed from the spray applied coating material. Just as in wallboard texture, the spray droplet size and amount of application controls the texture pattern from that of a light orange peel (the texture of an orange peel) to that of a heavily textured surface.
A preferred spray applied elastomeric building construction coating material product and system of the subject invention for bridging gaps in the sheathing layer uses a gap bridging fiber containing elastomeric coating material that is concurrently applied to gaps (preferably, all gaps) in the exterior sheathing layer as a first coating layer bridging these portions of the sheathing layer of a two coating layer system or a single coating layer bridging these portions of the sheathing layer. The ratio of fiber to elastomeric coating material in the fiber containing elastomeric coating material is sufficiently high so that the gaps are bridged with a coating layer containing a semi-continuous fiber web. The fibers utilized in the gap bridging fiber containing elastomeric coating material may be or include chopped glass fibers, chopped plastic fibers, cellulose fibers, small nodules of glass, plastic, or cellulose fibers, or mixtures of one or more of these fibers that function as a reinforcement and spanning material to facilitate the bridging of gaps with the spray applied elastomeric building construction coating material. For certain applications, the fibers may be contained in and sprayed with the elastomeric coating material. Where this form of application is precluded or not preferable, e.g. due to the amount of fibers to be included in the fiber reinforced coating layer being formed, the fibers can be sprayed concurrently with the elastomeric coating material and mixed with the elastomeric coating material as the coating material and the fibers are applied to the surface of the sheathing layer to form the fiber reinforced elastomeric coating layer. The exterior facing surface of the coating layer formed by the gap bridging fiber containing elastomeric coating material may be a smooth or textured surface and where the coating layer has a textured surface, the fibers may also contribute to the formation of the textured surface on the building wrap coating layer formed with the coating material.
Preferably, the gap bridging fiber containing elastomeric coating material of the subject invention will form a coating layer with a fiber web that has the ability to expand and contract with the sheathing layer with little or no degradation of the building wrap coating layer. This will enable the joints between sheets of sheathing, such as OSB sheathing, nonwoven glass mat faced gypsum sheathing board, and foam insulation sheathing, to expand and contract a few millimeters as these sheets transition between hot and cold and wet and dry without losing the desired waterproof, water vapor permeable, air barrier spray applied building wrap overlying the joints. For extreme applications, it may be beneficial to use fiber reinforcements that can stretch or elongate and contract e.g. the fibers are made of an elastic material, with the coating layer as the sheathing of the sheathing layer expands and contracts.
Where the gap bridging fiber containing elastomeric coating material is applied as the first coating layers of a two coating system, the first coating layers bridging the various gaps in the sheathing layer are permitted to dry and solidify sufficiently (a period of about one to several minutes) so that a second coating layer of an elastomeric coating material can be applied over and adhered to the first coating layers and the remainder of or other portions of the sheathing layer being coated to form a sprayed building wrap. In the two coating system, the elastomeric coating material forming the second coating layer may or may not contain the gap bridging fiber. Depending on whether a drainage plane or air wash is desired, the elastomeric coating material forming the second coating layer may or may not form an exterior facing textured surface. A uniform and sufficient amount of the second elastomeric coating material is applied to form the desired waterproof, water vapor permeable, air barrier spray applied building wrap over the entire surface of the sheathing layer and double reinforced waterproof, water vapor permeable, air barrier spray applied building wrap coating layers over and bridging the gaps in the sheathing layer. For the purposes of visualizing the finished two coating system, compare this operation to how interior wallboard is finished by first applying a paper or scrim tape over the joints and then covering the tape with a coating of wallboard mud. Similarly in the two coating operation of the subject invention, the first coating material is spray applied over the gaps in a sheathing layer to form, in-situ, spray-on tapes of the fiber containing elastomeric coating material. These on-site formed tapes are then covered with a second coating material that is spray applied over the on-site formed tape. The remainder of the sheathing layer is also spray coated with the second coating material to complete the formation of the spray applied building wrap.
Where the gap bridging fiber containing elastomeric coating material is employed as on-site formed, spray-on tapes to bridge gaps in an external sheathing layer, such as but not limited to oriented strand board (OSB) sheathing layers and foam insulation sheathing layers, the gap bridging fiber containing elastomeric coating material is concurrently spray applied over the various gaps in the exterior sheathing layer to bridge and close the gaps with a waterproof, water vapor permeable, air barrier coating layer (spray-on tapes). The spray-on tapes of the subject invention can be used to close the various gaps in an external sheathing layer with sheathing, such as oriented strand board (OSB) sheathing and foam insulation sheathing, and thereby form a waterproof, water vapor permeable, air barrier building wrap that can include only the spray-on tapes and sheathing. By closing the gaps in the exterior sheathing layer with the spray applied waterproof, water vapor permeable, air barrier coating layer of the subject invention, the labor intensive taping procedures normally employed to close these gaps is eliminated and the waterproofing, water vapor permeability, and air passage impedance of the exterior sheathing layer can be improved.
Preferably, the building wrap coating layer 22 has an air permeability of 0.004 cfm/ft2 [0.02 l/(s·m2)] @ 75 Pa or less when spray applied onto the exterior facing surface of the sheathing at a dry thickness of 0.12 inches or greater, more preferably at a dry thickness of 0.018 inches or greater, and most preferably at a dry thickness of 0.003 inches or greater. With regard to the building construction assemblies of the subject invention, such as the building construction assemblies 30, 50, and 60 of
Preferably, the building wrap coating layer 22 is waterproof at a dry thickness of about 0.12 inches, more preferably at a dry thickness of about 0.018 inches, and most preferably at a dry thickness of about 0.003 inches. Preferably, the building wrap coating layer has a water vapor permeability greater than 1 perm and more preferably, equal to or greater than 5 perms when spray applied onto the exterior facing surface of the sheathing layer at a dry thickness between 0.003 inches and 0.018 inches and preferably, at a dry thickness of up to 0.12 inches. While any level of emissivity is beneficial when combined with an air space intermediate the exterior surface of the building wrap coating layer and the interior surface of the cladding layer, preferably, the building wrap coating formed by the spray applied building construction coating material has an emissivity of less than 0.30, more preferably less than 0.10, and most preferably less than 0.045.
The spray applied elastomeric building construction coating materials of the subject invention may also include one or more of the following additives to further enhance the performance of the coating material and the building wrap coating layers formed with the coating material: termiticides(s), fungi growth inhibiting agent(s), phase change material(s), etc. The following are examples of fungi growth inhibiting agents that may be used in the spray applied building construction coating material of the subject invention: 2-(4-Thiazolyl) Benzimidazole (a chemical also known as “TBZ”), sold by Ciba Specialty Chemicals under the trade designation Iraguard F 3000; silver zeolyte sold by Rohm & Haas Company under the trade designation KATHON; and Zinc Pyrithione, sold by Arch Chemicals Inc. under the trade designation Zinc Omadine. The use of TBZ and Zinc Pyrithione together may have a synergistic affect to enhance the fungi growth resistance of the coating material.
Where it is desired to passively absorb and store excessive heat during a certain period (e.g. the day) and discharge heat during another period (e.g. the night) to maintain a more constant temperature within a building or room and conserve energy, the coating material of the subject invention can include one or more phase change materials, encapsulated within microcapsules, that latently store and release thermal energy. The microcapsules have shells that are preferably filled or substantially filled with the phase change material(s) and are typically about 5 to 10 mm in diameter. The microcapsule shells are impervious to the phase change material(s) in its/their liquid form, are not degraded by the phase change material(s), and can withstand the phase changes of the phase change material(s) (including the volume increases that occur during the melting cycle) without leaking. The phase change material(s) utilized in the microcapsules absorb energy (heat) during a melting cycle (fusion cycle) of the phase change material(s) where the phase change material(s) physically changes from a solid or crystalline form to a liquid form at a nearly constant temperature within the temperature range of about 65° F. (18° C.) to about 150° F. (66° C.) and release energy (heat) during a solidification or crystallization cycle where the phase change material(s) physically change from a liquid to a solid or crystalline form at a nearly constant temperature within the temperature range of about 65° F. (18° C.) to about 150° F. (66° C.). Due to the small volume increase and low vapor pressure exhibited when phase change material(s) physically change from a solid to a liquid, phase change material(s) are used in the microcapsules that undergo a solid to liquid phase change within this temperature range rather than a liquid to gas phase change, which would result in a huge volume increase. Paraffin waxes and other commercially available phase change materials may be used in the microcapsules that undergo solid to liquid and liquid to solid phase changes within the above temperature range and have a latent heat storage capacity of at least 160 J/g and preferably at least 180 J/g. The particular phase change material(s) selected for the microcapsules is selected in part for having its/their phase change occur at a desired temperature within the temperature range set forth above in this paragraph.
An example 30 of a typical building construction assembly of the subject invention, forming part of an exterior building wall 32, includes: an exterior wall sheathing layer 34 overlying and secured to the exterior facing surfaces of load-bearing, wall framing members 36 of the exterior building wall; the building wrap coating layer 22 spray applied to, overlying, adhered to, and coextensive with or substantially coextensive with the exterior facing surface of the sheathing layer 34; and an exterior wall cladding layer 38 overlying the exterior facing surface of the building wrap coating layer 22. As shown in
An example 50 of a typical building construction assembly of the subject invention, forming part of a sloped roofing system shown in
Another example 60 of a typical building construction assembly of the subject invention, forming part of an exterior building wall 62, includes: an exterior wall sheathing layer 64 overlying and secured to the exterior facing surfaces of load-bearing, wall framing members 66 of the exterior building wall; the building wrap coating layer 22 spray applied to, overlying, adhered to, and coextensive with or substantially coextensive with the exterior facing surface of the sheathing layer 64; and an exterior wall cladding layer 68 overlying the exterior facing surface of the building wrap coating layer 22. As shown in
In describing the invention, certain embodiments have been used to illustrate the invention and the practices thereof. However, the invention is not limited to these specific embodiments as other embodiments and modifications within the spirit of the invention will readily occur to those skilled in the art on reading this specification. Thus, the invention is not intended to be limited to the specific embodiments disclosed, but is to be limited only by the claims appended hereto.
