Our house, a 1600 sq. ft. bungalow, was built in 1973.This winter, several noticeable cracks have appeared where the wall and ceiling meet...in the dining room, bedrooms,hallway...all on interior walls on the main floor. There have been no recent renovations done. There are no bearing walls. We had above 0 C temp until the end of December and then a cold spell of minus 30 -40 C. The rest of the winter was cold with very little snow. Our house temperature is generally set at 19 C. We have a wood fireplace insert in the finished basement which is used to provide a more comfortable temp in the rec room. Does this sound like a moisture related problem or should I be looking at the roof trusses?
Answer:
It sounds very much like a condensation problem that freezes and then pulls your attic floor joists out of configuration as it expands and contracts in reaction to moisture content and temperature fluctuations. It is known in the trades as 'rafter lift' and I normally inform people of the following: ceiling joists responding to varying amounts of moisture content and then impacting on the drywall joints where walls and ceilings meet. You can normally get away from permitting that joint to open by not having ceiling drywall fasteners nearer than 12 to 16 inches from the walls. That way, when the ceiling joist lifts or disfigures in any direction, ceiling drywall stays where it is because it will bend enough to not tear the tape.
