A Common Cause for Humps & Squeaks

I inspect many floors where joints between subfloor panels are an issue. If the panels expand and push together, the edges can lift up, causing humps or squeaks in the floor. Most subfloor panels are stamped with a label indicating the spacing that should be left between panels at installation:

However, the labels are usually on the underside of the panel and not visible from the installation side. Many tongue-and-groove panels are formed such that light force is needed to properly interlock the tongues and grooves, and to provide the proper gap. Panels can also be cut slightly shorter than the nominal 8 foot length to allow for proper spacing. However, some contractors think that the joints should be tight, and even use sledgehammers to close the gaps.  

The APA (Engineered Wood Association) has recently released an online video designed to educate builders about this common subfloor panel installation error. In Prevent Buckling with Proper Spacing, APA Senior Engineered Wood Specialist Bob Clark explains APA's recommendations for correct spacing between plywood and OSB panel joints, and demonstrates how improper spacing can result in panel buckling. The video is based on APA Builder Tip: Prevent Buckling with Proper Spacing, which provides APA panel spacing recommendations for APA Rated Sheathing, APA Rated Sturd-I-Floor, and APA Rated Siding. APA Builder Tips address common topics or challenges in today's building environment, such as panel buckling, squeaky floors, and nail pops, and are designed to help construction professionals save money and improve quality on the job through improved construction practices. Maybe this video or builder tip will help prevent some of our common hardwood floor issues. Pass it along to your contractor friends.