Expert: Bruce E. Johnson - 11/13/2008

Question
Dear Bruce,
I have a home that was built in 2001.  I've been in the house since 2004.  Every winter, when it gets cold, the ceiling raises and long craks appear in the ceiling along the tape lines at interior walls.  This happens in every room including hallways.  The crack in some spots is 1/4". In other words, the ceiling is 1/4" higher than the wall.  This only happens upstaris, not on the main level.  In spring when thing warm-up the ceiling drops leaving only a hairline crack.  The attic is filled with blown in insulation.  Patching is only a temp. fix, any suggestions for a more permanent fix?

Answer
Hi Mike, what you are probably experiencing is expansion and contraction in your roof system.  You didn't say how cold is cold where you live or what type of roofing you have, shingles, metal, tile?  If you have ever been in an attic in the summer time you know how freaking hot it gets.  That's why you have or should have some kind of vent in the attic to help eliminate that heat.
 When materials get hot they expand, some expand more than others.  Wood expands more than drywall ( a gypsum product).  Inversely when it is cold materials contract, some contract more than others.  So it seems possible that in the winter, the cold in your attic is causing the previous warm and expanded wood to shrink and contract.  This would explain why it is only happening in the attic portion of your house.  Or the walls supporting the roof system.
 In Florida we have the opposite problems, too much heat in the attics.  As of late we have been insulating up against the bottom of the roof sheathing between the rafters and using an unvented sealed attic space.  This turns the attic space into heated/cooled space and allows the roof system to maintain a more constant temperature and thus keep the expansion and contraction to a minimum.
  If you were experiencing this phenomona on the first floor somewhere then I might lean toward your foundation heaving from the frozen soil expanding beneath it.  But I opt for the attic at this point.  Whether or not insulating your rafters will help in your case I can't say for sure without a first hand look at the way your structure is built.  I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com