Patent Application
20200318345
This present invention relates generally to exterior wall board systems used in the construction of residential and/or commercial buildings that provide a water-resistive barrier and shear strength, and more particularly to a cement wall board system.
Building codes today require that certain walls of wood or steel framed buildings be capable of taking shear loads. Typically, ⅜ inch to ⅝ inch wood-based sheathing have been installed on the interior or exterior side of the framing studs to take such shear loads. It is common practice to install ½ inch to ⅝ inch thick drywall panels, such as gypsum wallboards, on the interior sides of the framing studs and a ⅞ inch stucco system or other suitable material with a water-resistive barrier on the exterior side of the framing studs.
In general, most wall board systems used in construction are susceptible to water and moisture intrusion, which can cause water damage and corrosion. Internal (hydration) cracks and external (stress) cracks, which can form as a result of installation error or building movement, can increase the amount of damage caused by the water intrusion.
Specifically, wood-based sheathing, lath and organic water-resistive barriers (such as building paper), which are used in typical stucco systems, are particularly susceptible to corrosion caused by water. For example, in a typical one-coat stucco system 100, wood-based sheathing such as plywood or OSB 110 is attached to studs/framing 120 using mechanical fasteners (not shown), as shown in
Similarly, in a three-coat stucco system 200 shown in
In both the one-coat and three-coat systems described above, water can infiltrate the stucco layers, which can cause corrosion of the lath, water-resistive barrier, and wood-based sheathing. Accordingly, a new type of exterior wall board system is needed to solve these problems.
In a typical Exterior Insulation Finish System (EIFS) shown in
Another problem with the aforementioned wall board systems is that the system is complicated and produces a lot of waste materials, which makes clean up more burdensome.
At least one embodiment of the present invention is directed towards a novel exterior cement wall board system that can provide shear strength, protection from water/moisture damage without using any wood-based sheathing and/or building paper or any other component that can suffer from water damage. Specifically, at least one embodiment of the present invention combines drainage channels with a structural board such as a cement board. In at least one embodiment, this is done by forming the cement or concrete compatible adhesive with the proper thickness and spacing behind the cement board. The cement board system does not require any metal lath, wood-based sheathing and/or building paper or any other component that can suffer from water damage. The system also reduces construction time, minimizes clean up, and is more durable than other exterior wall systems such as an EIFS.
These and other features and advantages will be apparent from a reading of the following detailed description and a review of the associated drawings. It is to be understood that both the foregoing general description and the following detailed description are explanatory only and are not restrictive of aspects as claimed.
The invention will be more fully understood by reference to the detailed description, in conjunction with the following figures, wherein:
The subject innovation is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerals specific details are set forth in order to provide a thorough understanding of the present invention. It may be evident, however, that the present invention may be practiced without these specific details.
As shown in
A fluid-applied water-resistive barrier 440 is adhered to the outer surface of the inner cement wall board 410. This fluid-applied water-resistive barrier 440 can be sprayed or rolled on the outer surface of the inner cement wall board 410 to a thickness of approximately 10-12 wet mils. Parex WeatherSeal can be used as the fluid-applied water-resistive barrier 440. Also, any fluid-applied water-resistive barrier that complies with IBC Section 1404.2 or IBC Section R703.2 can be used. A cement or concrete compatible adhesive 450 is applied to the fluid-applied water-resistive-barrier 440 to adhere an outer cement board 460 to the fluid-applied water-resistive barrier 440/inner cement wall board 410. For the outer cement wall board 460, a nominal ⅜ inch or ½ inch cement board that is functionally equivalent to the cement boards manufactured by Nehemiah Elite Wall Systems, Inc. can be used. An adhesive such as Teifs Base EIFS Basecoat & Adhesive can be used as the cement or concrete compatible adhesive. The cement or concrete compatible adhesive 450 is applied in an amount sufficient to adhere the outer cement board 460 to the water-resistive-barrier 440/inner cement board 410 such that drainage channels 470 are formed between the water-resistive barrier 440 and the outer cement board 460. That is, the drainage channels 470 are formed within the cement board system between the inner cement wall board 410 and the outer cement board 460.
The drainage channels 470 can drain water and moisture trapped within the board system, which can prevent water damage. The drainage channels 470 can be formed, for example, by applying the cement or concrete compatible adhesive 450 in the form of vertical strips spaced approximately ¾ to 1½ inches apart with each strip having a width and thickness of approximately ⅜ inch. The vertical strips extend substantially the entire height of the cement boards 410/460. Therefore, the system of the present invention forms a water-resistive barrier, and a drainage system to remove any water/moisture that occurs.
The cement board system described herein combines structural support through the cement wall boards and drainage by the drainage channels formed between the inner and outer cement boards. Also, said cement board system does not require any wood-based sheathing or organic water-resistive barriers that can be prone to water damage.
After the cement board system 400 is fastened to the studs 420, two (2) layers of approved base coat 480 with a fiberglass mesh 490 adhered therebetween can be applied to the outside of the outer cement board 460 in order to seal the outer cement board 460, as shown in
The system shown in
The cement board system 400 of the present invention can be used with a perforated starter track similar to a termination (weep) screed used in a typical stucco system at the bottom of the wall board system 400.
It should be understood that the invention is not limited by the specific embodiments described herein, which are offered by way of example and not by way of limitation. Variations and modifications of the above-described embodiments and its various aspects will be apparent to one skilled in the art and fall within the scope of the invention, as set forth in the following claims. For example, various similar materials can be used in the cement board system without departing from the scope of the invention.
