CA2302795C

CA2302795C - Building wall humidity control system

Info

Publication number: CA2302795C
Application number: CA002302795A
Authority: CA
Inventors: Kenneth G. Dextras
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-03-22
Filing date: 2000-03-22
Publication date: 2002-07-30
Anticipated expiration: 2020-03-22
Also published as: US20020073628A1; CA2302795A1

Abstract

The invention relates to a system (and devices) for controlling the moisture in framed building walls by controlled forced ventilation. The object of the invention is to improve the long term structural performance of the wall by keeping the moisture in the wall cavity below acceptable levels. The invention can also be used to help identify possible water related breaches or defects in the wall at specific locations.

Description

Description Technical Field The invention relates to the exterior wall construction of frame buildings for residences, apartments, office buildings and the like. Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention.
Background of the Invention It is common in the method and materials used to construct frame building walls, that relatively airtight cavities are created such that natural ventilation of the said cavities is prevented or seriously reduced. Since frame building walls are not absolutely watertight, the net result over time is that excess moisture (or humidity) accumulates in the cavities thereby causing mould to form and eventually causing structural damage to the wall itself. Also, present day methods and materials effectively allow these moisture related problems to go on undetected for long periods of time.
The prior art does contain modifications to the common method and materials to generally improve air circulation such as described in Canadian application no.

2,148,626 by Fitzgibbon and in U.S. patent no. 4,393,633 by Charniga. However, all of these are strictly passive arrangements that do not measure, control or manage any specific parameters whatsoever.
Because of this, the net effect that the prior art systems could possibly have on any specific parameters, such as moisture content or relative humidity for instance, is unknown. Also, these systems require significant changes to the standard framing members which in turn poses a serious limitation on commercial feasibility.
The present invention is a system whereby specific parameters such as moisture content and relative humidity are measured, managed and controlled without significant changes to the standard framing arrangement.
Summary of the Invention The invention controls moisture in frame building walls by enabling dry interior air to pass through the wall cavity by means of a forced ventilation system that is controlled by a moisture control mechanism connected to moisture probes installed in the said cavity and which exhausts this air to the exterior. The system operates on demand such that when the probes detect that the moisture content or humidity in the cavity exceeds predetermined values, the control mechanism activates a fan which continues to operate until such time as the predetermined values are reached and upon reaching same, the mechanism then shuts off the fan. The air circulation is achieved by connecting the fan works to a series of specifically designed hollow headers and exhaust ports which form part of the wall itself but do not require significant changes to the standard framing arrangement of a conventional building wall.

Brief Description of the Drawings Figure 1 is a plan view showing a typical general arrangement of the present invention in a new construction application.
Figure 2 is a section view of the system of Figure 1.
Figure 3 is an enlarged detailed portion of Figure 2.
Figure 4 is a plan view showing a typical general arrangement of the present invention in a retrofit application.
Figure 5 is a section view of the system of Figure 4.
Figure 6 is an enlarged detailed portion of Figure 5.
Detailed Description Referring to Figures 1, 2 and 3, it can be seen that a typical new construction general arrangement is disclosed. A standard exterior load bearing wall is comprised of an exterior wall portion 1, an interior wall portion 2, a perforated hollow top plate header 3, a perforated hollow bottom plate header 4 and in the cavity thus defined, is found insulation 5, insulation spacers 6 and moisture/humidity probes 7. When the probes detect that the moisture or humidity in the cavity exceeds predetermined values, a moisture control mechanism 8 activates a fan 9 which draws dry interior air 10 and forces it through a connector pipe 11 and the components of the stud space defined above. The air is allowed to escape to the exterior by means of exhaust ports 12 located at the ends of the top plate header 3. Once the predetermined moisture/humidity values have been reached, the mechanism 8 shuts off the fan 9. In this way, the invention is able to keep the moisture/humidity levels in the cavity below acceptable levels thereby preventing mould growth and the structural damage associated with same.
Referring to Figures 4, 5 and 6, it can be seen that a typical retrofit general arrangement of the present invention is disclosed. This arrangement is essentially the same as the one described above except that the hollow top plate header 3 and the hollow bottom plate header 4, are constructed by cutting open and expanding inward the interior wall portion 2. Also shown is a different configuration for the insulation spacers 6, which, if used, may require a slightly higher capacity fan 9 to overcome the small increase in friction head loss at the interface of the insulation 5 and the inboard edges of the interior and exterior wall portions. With these changes and the same previously described control arrangement, this retrofit application can achieve the same objective of keeping the moisture/humidity levels in the cavity below acceptable levels thereby preventing mould growth and the structural damage associated with same.
Also, for both of the applications described above, the frequent automatic operation of the system can act as an early warning that possible water related breaches or defects in the wall have occurred at specific locations. This can enable the owners) to take corrective action in a timely manner thereby preventing damage that might otherwise grow out of control if left undetected.

Claims

1. An improvement in a system to control moisture in an exterior load bearing wall construction having a plurality of stud members connected to lower plate and upper plate hollow and perforated headers, interior and exterior wall portions and in the stud spaces thus defined, moisture/humidity probes are installed such that if the moisture in the framing members or the humidity of the air in the stud space exceeds predetermined values, a moisture/humidity control mechanism actuates a fan that draws regulated interior air from the living space, forces it into the lower headers, the stud spaces and the upper headers and exhausts it to the exterior by means of exhaust ports connected to the upper headers through the exterior wall portion and continues to operate until such time as the predetermined values are reached and upon reaching same, the mechanism then shuts off the fan.

2. An improvement in a system to control moisture in an exterior load bearing wall construction having a plurality of stud members and plates connected to lower plate and upper plate hollow headers installed externally to the wall construction, interior and exterior wall portions and in the stud spaces thus defined, moisture/humidity probes are installed such that if the moisture in the framing members or the humidity of the air in the stud space exceeds predetermined values, a moisture/humidity control mechanism actuates a fan that draws regulated interior air from the living space, forces it into the lower headers, the stud spaces and the upper headers and exhausts it to the exterior by means of exhaust ports connected to the upper headers through the exterior wall portion and continues to operate until such time as the predetermined values are reached and upon reaching same, the mechanism then shuts off the fan.

3. The system of claim 1 or claim 2 wherein insulation is installed in the stud spaces.

4. The system of claim 1 or claim 2 wherein insulation and insulation spacers are installed in the stud spaces.

5. The system of claim 1 or claim 2 or claim 3 or claim 4 wherein the moisture/humidity control mechanism contains a manual override means to enable manual operation independent of the probes.