Strapping Ceiling Joists: Ceiling Drywall Installation Prep

Ceilings have a way of really showing defects when the drywall is not installed properly. While the visibility of ceiling defects can be reduced (e.g., through recessed lighting, flat paint, and other methods), the goal of every ceiling drywall installation should be to reduce or eliminate errors during construction. Everyone likes a clean-look drywall ceiling!

The first step in preparing the ceiling is to ensure there are no major issues with the sub-structure of the joists above, no plumbing or electrical issues to be addressed, and that, in general, you can live with a sealed ceiling. After that’s complete, the ceiling should be strapped to ease installation.

What is Ceiling Strapping?

Strapping a ceiling is the process of installing wood (or, in advanced installations, another material) perpendicular to the joists. The strapping serves as the nailing surface for the drywall. You should never install ceiling drywall fastened directly to the joists above. Why? There are several good reasons:

• If the ceiling has a floor above, the odds that the drywall will eventually crack and come away from the ceiling is greatly increased. Unlike wall installations where the studs never move, joists flex under the weight of foot traffic and furniture above, creating uneven stresses on the drywall.
• Installation is about 5x more difficult! Without strapping, you’d be attempting to nail the drywall joints on only half of a side of 2x lumber. While this can be done on wall installations, it’s not by any means desirable.
• You’ll end up with more seams. By strapping the ceiling, you ensure optimum nailing surface and spacings for drywall.

Strapping the ceiling also has the added benefit of reducing noise transfer from the floor above if you use an advanced material like resilient channel instead of 1×3 wood.

Purchasing Wood Straps

Ceilings are most often strapped with 1 x 3 uniform spruce lumber. Most home improvement stores will sell strapping in bundles, with sizes ranging from 8 feet to 16 feet. In general, you want to buy the longest strapping you can transport / install in the space.

Calculating the amount of strapping you need is simple. Measure the ceiling across perpendicular to the joists. Take the number of inches and divide by 16, then add 1. That gives you the number of straps to be installed. Measure the ceiling parallel to the joists. If this number is less than 16 feet, you can buy one strap for each length. If this number is greater, you’ll need to be additional straps to be installed on each length. Pick the best combination of strap lengths to achieve the ceiling.

How to Install Ceiling Strapping

Ceiling strapping should be installed every 16 inches on center, perpendicular to the joists above. Remember, a sheet of drywall is 4 feet, or 48 inches wide. 16 inch on-center spacing allows the drywall to be fastened four times across its width (one on each end, and two in the middle).  On-center installation is important, because every 48″ the strapping will be shared by two pieces of drywall. In other words, the center of the third piece of strapping from the wall should be 48″ away from the edge. This pattern should be followed all the way across the ceiling.

To keep the strapping perpendicular to the wall and in a straight line, you may want to snap a chalk line across the joists after making measurements, and before installing the strapping.

Use The Right Nails

10d nails are appropriate for ceiling strapping. You can use two nails at every intersection between a joist and the strapping. We highly recommend using a framing nailer to speed installation! (Otherwise, you’d be swinging a hammer upside down a few hundred times!)

Do not use finishing nails! Finishing nails will not provide sufficient hold in the ceiling above.  Eventually, the strapping will pull away from the joists, and you’ll have a collapsed ceiling.

We recommend against screws only because of the unnecessary added installation time.

Summary & Credits

Installing ceiling strapping greatly eases drywall installation on the ceiling and ensures a smoother, even drywalling job.  Special thanks to Todd over at Home Construction Improvement for helping us out with this article and for providing the two photos above.

by: Fred | November 3, 2009 | filed in: Projects
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