I read your question/answer article in Winnipeg Free Press Sunday Homes and find this very helpful. I have a problem of my own and am hoping you can provide your input to correct the problem.
I have a cathedral ceiling for my Kitchen/Great Room and at the peak of the cathedral ceiling a crack has occurred. This crack starts from the peak of the cathedral ceiling and continues downward for about another two and a half feet. The distance from the floor to the peak is about sixteen feet. Here's the problem. In the winter it is simply a hairline crack, however, in the summer this crack opens leaving a quarter inch gap. This has been occurring since the house was built. Obviously, the change in temperature has an affect on this crack.
How do I fix this? How do I prevent this expanding and contracting?
Note: The house is only five years old. This is occurring on the inside
wall (drywall) and there is a telepost in the basement underneath the peak of
the cathedral ceiling.
Hairline drywall cracks occurring in newer homes is a common occurrence due to shrinkage in building materials and drywall taping compound in the first few years. Often individual sheets of drywall may not be tightly fastened to the wooden studs behind and the screws may become visible and joints in the drywall open. Much of this occurs in first couple of years, and should not reoccur after tightening of screws and minor patching is done.
Larger cracks or recurring ones often have a deeper root to the problem. It is difficult to accurately determine the design of your home from his brief description, but it appears that the offending crack may be caused by more than simple shrinkage. The first attempt at repairs should be to install additional drywall screws on both sides of the crack. If the crack is a drywall joint, and it appears that this is the case, there should be wooden framing behind to bridge the joint. If the newly installed screws cannot find their mark, then the lack of backing may be part of the problem. Once the drywall is better secured, the joint should be patched using drywall compound and tape. This repair is ideally done when the crack is near the narrow range of it’s movement, and should be monitored once patched and painted.
If this newly patched joint opens again in the warm summer weather, then there is likely a structural reason for the joint’s expansion. It is unlikely that ambient temperature has much effect on a crack in an interior wall, but corresponding moisture levels may have some effect. If the crack expanded in the winter, I would suspect a change in moisture within the home, but the reverse is occurring. The relative humidity within a home is normally much lower in the winter and I would expect the drywall and filler to expand with the higher humidity in the summer, and close the gap. The key to this problem likely lies with the design of the home and the telepost below the peak of the ceiling.
The footings below the foundation walls and teleposts in the home will move somewhat with the seasons. This is the reason that teleposts are adjustable, to allow for raising or lowering as needed. The soil in our area is known as expansive clay soil, which will swell when saturated or when the frost leaves the soil during the annual spring thaw. In new homes, basement floor slabs and internal footings below, normally heave somewhat for several years after construction. This is the cause of common cracks seen in the basement floor slabs. To accommodate this, teleposts should be lowered slightly, and the main beams in the home straightened.
In your home, it appears that one of the offending teleposts is directly below the peak of the ceiling. After the spring thaw and with summer rains, the soil around and below the house may swell, pushing up on the footing below the telepost. In the winter, the soil may shrink and allow the crack to close as the footing recedes. This may continue to occur for many years, as long as the moisture level in the soil varies from season to season.
The simple solution to this is to carefully and slowly adjust the telepost below the peak of the ceiling when the crack opens up. This should be done gradually, with no more than ¼ of a turn of the screw-head at a time. It may also be necessary to check and adjust other teleposts in the home, as they may have similar movement, but without the obvious effects. Checking for interior doors rubbing on jambs or the flooring may be one indication of a need for telepost adjustment. Much of this settlement in occurs within the first 10 to 15 years after construction of the home due to the disturbance of the soil. Regular monitoring and adjustment of teleposts during this period will minimize wall and ceiling cracking, humps in the floors and other concerns in the home.