Wall cracks? Fight back

When drywall repair won't do

By Inman News Feed
Add Comment Add Comment | Comments: 0 | Posted Feb. 24, 2010

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When drywall repair won't do

Bill and Kevin Burnett
Inman News

Q: Our 4-year-old home has developed a crack down the seam of one interior wall, across to the next and then down another seam. A drywall taper repaired the crack by retaping it and finishing the seam. It looked great.

About six months later, I noted another crack in the same area. Two weeks later, the crack disappeared. I have access to the back side of the wall, so I reinforced the two studs by placing blocking between them and the adjoining studs. Everything was great for about six months, until today, when I noticed a new crack. I was told that it is because the studs are expanding and contracting with the weather.

I find that hard to believe because it is happening in only one place. I have considered taking the wallboard down and spanning the two studs with one piece of wallboard. What can you advise?

A: Believe it: Expansion and contraction of the wooden framing wall is the cause of the crack. The wall is moving in the horizontal plane. This is known as "racking." The telltale sign of horizontal movement is that the crack extends from one vertical seam to the next, as evidenced by the diagonal crack.

Removing and replacing the drywall won't fix the problem. You need something stouter.

Since you have access to the back of the wall, we suggest you create a shear wall by screwing sheets of either 3/8-inch plywood or 7/16-inch oriented strand board (OSB) to the studs using 1 1/2-inch wood screws.

Make sure to screw the sheets to the top plate and bottom plate of the stud wall. You can accomplish this in one of two ways. If you hang the sheets vertically, simply cut the sheet so that is spans the entire wall top to bottom. If you hang the sheets horizontally, install blocking in the wall so that the horizontal edges of each sheet can be screwed to the blocking and the top or bottom plate.

The goal is to get purchase on a stud, top plate, bottom plate or piece of blocking on all edges of plywood or OSB.

Screw the sheet on the edges and to each stud at 6-inch intervals. This will transform the stud wall from a series of moving parts to a monolithic structure that won't move under normal loads. Make sure to drill 1 1/2- to 2-inch holes through the sheeting in each stud bay for ventilation. The next time you re-tape, refinish and repaint, the crack will be gone for good.

Q: I have a question concerning the cracks in my walls. The walls shift depending on the season, so the cracks shift as well. I don't want to make repairs during winter just to have the cracks return in summer, and vice versa. Is there anything on the market that is flexible enough to handle these crack shifts?

A: Kevin has the same problem in one corner of his house. One maddening crack at the corner where a beam intersects a wall continued to open and close with the seasons. Over the years he has re-taped the crack a number of times but to no avail. The pesky crack always came back.

Recently Kevin talked to a painter who recommended trying elastomeric caulk to bridge the gap. Elastomeric caulk is a rubber-like compound that remains flexible. A couple of months ago, he tried it and so far it's OK. No guarantees but spend a couple of bucks and try it.

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