Q:

I’m building an addition for a customer who insists that there be no floor squeaks, so I’m taking every precaution I can think of. I’m using I-joists for the floor system, and gluing and screwing a tongue-and-groove OSB subfloor. I’m using felt paper between the subfloor and the prefinished 3/4-in. engineered-wood flooring. Am I missing anything?

Tyler Christopher, Rhinebeck, NY

A:

Editorial adviser Mike Guertin replies: You’re on the right track and have covered the most important elements: joists and subfloor attachment. There’s no way to ensure that there will never be squeaks, but here are a few other things that you can do to minimize the risk.
• Screw down partition walls. Nails securing the bottom plate can squeak when someone walks near the wall. Screws reduce the chance of this movement.
• Install midspan joist blocking with glue and nails. I-joist floors often require blocking panels in the middle of the span. Any movement between the joists and the blocks can cause noise. If blocks are being used, apply construction adhesive to the I-joist flanges where the blocking panels meet, and then toe-screw the flanges together.
• Use isolation membrane or adhesive at hangers. Any metal hanger can squeak when the joist or beam sitting in it moves. Apply a piece of self-adhering flashing tape or thin plastic flashing material to the beam that the hanger will be mounted to, and then do the same around the end of the joist or beam that will rest in the hanger. The isolation material won’t stop the movement, but it will dampen the noise.
• Install baseboard and other trim after the wood flooring is installed. This is a good measure for concealing the expansion gap required by most engineered-flooring manufacturers, but it also prevents squeaks caused when flooring butted to previously installed baseboard moves as people walk by.
• Install spray foam under the subfloor. This is an extreme measure and may be cost prohibitive. Spray foam deadens the sound of floor squeaks, so even if your preventive measures don’t stop all squeaks, at least they won’t be as loud.