Our house was built in 1997 and the contractor used prefab trusses. The first w

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   healthgalposted 14 years ago

   Our house was built in 1997 and the contractor used prefab trusses.  The first winter I noticed...
   
   a few holes, about the size of a quarter, where the drywall meets the ceiling.  I called the contractor back and showed him.  He talked with someone about the prefab trusses and said there is a natural phenomen that can occur and the trusses float in the winter time.  He came in and put molding all through the house to cover up the small holes.  Every winter in the middle of the house I can see where the drywall pulls away from the ceiling, but goes back when spring arrives.  This past winter was extremely bad and we had more snow.  This is the worst I have ever seen it pull away and in some p

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   drbillfanninposted 14 years ago

   I've never heard of such a thing, but I live in Georgia, USA. I've been in construction for 40 years. I would talk to neighbors and find out if other homes have the same problem. This could be a bad design or bad construction. Homes are not supposed to float up and down so much as to cause holes and separation of the drywall. A few stress cracks from settling are normal. What you are describing isn't.

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   mikeholmesfanposted 14 years ago

   yes, this does happen with long prefab truss in cold climates (north of Georgia).   While screwing thru the truss and into the top plate of internal walls sounds like a fix, it does not help since it will pull the top plate up, and can sometimes cause the bottom cord of the truss to crack. Your builders approach was a cosmetic fix which is commonly done.  It doesnt address air leakage through the gap into the attic though.

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   tahoppesposted 14 years ago

   This is a common phenomenon (Ohio) known as "truss uplift".  It is worst in climates where you have a great seasonal temperature differential, and worse with longer trusses. The trusses will lift up (greatest at mid-span) and cause the drywall joint at the wall-ceiling juncture to crack apart.  It doesn't help to screw the trusses to the top of the wall, the uplift is going to happen and you will just have a crack somewhere else.  You can minimize the effects of this by using proper dywall nailing techniques.  Don't nail (or screw) the ceiling drywall into the truss within 18-24 inches of a wall, and put a drywall backer blocking on top of the interior walls.  That way, when the truss lifts, the ceiling drywall will flex, and a crack is prevented.  There are many products available such as metal clips to take the place of blocking.  Some type of crown molding is a good way to fix the situation, after the fact.

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