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How to fix expanding/contracting drywall crack.

How to fix expanding/contracting drywall crack.


Old 01-22-07, 06:22 AM
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Join Date: Jan 2007
Location: USA
Posts: 10
How to fix expanding/contracting drywall crack.

I have about a 3 ft. long crack running horizontally along the ceiling area of my drywall in a stairwell--about 6 inches out from where its end joins that of the wall. (Other side of ceiling is the attic.)

Problem with repairing: The ceiling drywall actually drops downward a good 1/4 inch at the edge of the crack every winter. It then retracts back into place during the warmer months. (It wouldn't budge when I tried forcing it into place.)

I don't think vinyl spackling can handle 1/4 inch of movement. Is there anything I can do to correct the seasonal rise and fall of the drywall section? It is apparently moving in response to something expanding and contracting seasonally. If so, what could it be?
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Old 01-22-07, 09:45 AM
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Join Date: Mar 2005
Location: USA
Posts: 43,837
Generally a crack of that size is fixed with tape and joint compound but until the movement is corrected I be leary of any repair lasting.

Look in the attic and see if you can tell if the drywall is lacking in support. I assume you can't push the drywall up tight because it is already tight against the rafter. Maybe adding 2x's to support the drywall better will stop the movement - or atleast make both sides of the crack stay relative to each other.
Old 01-22-07, 04:34 PM
Join Date: Feb 2006
Location: USA
Posts: 6,392

This condition is caused by movement of the roof trusses. The structural engineers have a name for it, but I do not remember what it is. It is prevented by installing the wall framing in such a way that it is not attached directly to the truss at the top of the wall. Instead, a lateral support system is used to support the top of the wall. The ceiling drywall should not be nailed or screwed to the roof truss within 16-24 inches of the wall in question. This allows the edge of the ceiling drywall to remain attached to the wall drywall and avoid the crack.

Last edited by Wirepuller38; 01-22-07 at 04:35 PM. Reason: To correct spelling.
Old 01-30-07, 06:30 PM
Join Date: Jan 2007
Posts: 1
I have the same issue going on. What I think I'm going to do is install molding, possibly crown, in that room and nail it to the ceiling instead of the wall so that it can cover the crack in the heat and in the cold.

I also found this information:

The seasonal opening and closing of the joint between the ceiling and the wall is caused by roof truss movement. This is commonly known as truss uplift. During the winter, the part of the truss immediately above the ceiling is exposed to higher temperatures and lower humidity than the parts of the truss immediately below the roof deck. These parts see lower temperatures and higher humidity. They pick up condensation that forms on the underside of the roof deck. As a result, the lower part of the truss tends to shrink slightly during the winter, while the parts immediately below the roof deck tend to swell. In turn this causes the upper parts of the truss to bend the bottom of the truss upward. This lifts the ceiling below, and cracks develop where the wall and ceiling meet. This condition can be prevented with construction techniques, but the best way to deal with the problem now is with a cosmetic repair. You were correct to have moldings installed, but the moldings should have been nailed to the ceiling, not the wall (as is typically done). The moldings should be free to move up and down with the ceiling. As long as the molding is wide enough, it will cover the crack at the ceiling.


Good luck,

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