Download PDF version (66.6k) Log In or Register to view the full article as a PDF document.
Q.On a recent project, several hundred screw pops showed up on the primed walls and ceilings. About half the boards in the house had to be rescrewed and patched, and all the drywall had to be reprimed. Although it was raining when the drywall was stocked, my drywaller says he did not use any of the sheets that got wet. According to him, the problem was caused by shrinkage in the framing — but construction conditions were normal, with no obvious evidence of excessive moisture levels in the lumber. What happened?

A.Myron Ferguson, a drywall contractor in Galway, N.Y., responds: It takes about 1,000 screws to hang 1,000 square feet of drywall, so it’s not uncommon to have a dozen or so screw pops in an average house.

Screws set too deeply might be fine when the drywall is sanded, but may pop when there’s structural movement or an impact. Also, insulation can push against the drywall and prevent it from being fastened tight to the framing; later, pressing the drywall back against the framing can cause pops to occur. And finally, when framing dries and shrinks, a gap can open up between it and the drywall; screws that are too long are more likely to pop when this happens than properly sized drywall screws, which should penetrate the framing only about 5/8 inch.

But it’s unusual to have hundreds of screw pops. While conditions are seldom ideal on any site, most drywall installations experience minimal popping. In your case, it’s likely that a “perfect storm” of factors — lumber with relatively high moisture content, damp drywall, perhaps high humidity and low airflow, even improperly set screws — all contributed to the problem.

Most of the excessive popping I’ve experienced has occurred along the top plate, so now I avoid fastening drywall within about 7 inches of the ceiling. I’ve found that using drywall adhesive helps reduce fastener pops and provides extra insurance against minor structural movement or improperly set screws. (I always specify adhesive when working with an installation subcontractor.)

Working with dry framing helps, too. Whenever I can, I bring the drywall inside ahead of time and allow it to acclimate (same as with hardwood flooring), and I try to control temperature, humidity, and airflow before, during, and after the drywall work.