Any ideas on glues or adhesive when sistering floor joists and plywood to fix a bouncy floor.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story

Mike Guertin explains how Pella Steady Set windows are revolutionizing the glazing game and provides a helpful installation tutorial.
Highlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
@ts2021
I recommend using polyurethane construction adhesive in 10 oz caulk tubes for ease of dispensing in tight spots. If you have the room to use the 28 oz cartridges and larger caulk gun, go for it. PL Premium 3x is my preferred adhesive for this application - it guns easily as long as the stock isn't expired and the product is at least 50 degrees F, and it won't sag or drip as you apply it along the length of your joist before you get the sister member in place. It remains slightly flexible after curing which is a characteristic you won't see in less costly construction adhesives. I like to use short structural screws from Simpson or FastenMaster rather than framing nails (and never deck screws) because the structural screws really draw the pieces together, promoting good coverage because the glue will spread out as you tighten them up. I run a continuous bead of adhesive along the joint of the subfloor and the top of the existing joist, then do a wide overlapping "X" pattern on the face of the joist.
If using sawn dimensional lumber for your sister pieces, make sure to check the crown before installing and install crown up.
Thanks. I'm familiar with PL. I'm also a fan of Simpson structural screws even though they are a bit pricey. I've found that some use wood glue and in my opinion is overkill.
@ts2021
Just trying to help; I wasn't sure of your level of experience based only on your original question. Without knowing the condition of your floor joists and the amount of bounce/deflection you're experiencing, I still think if you're going to the trouble of sistering joists to mitigate bounce, it's worth the extra bucks to adhesive-bond the new to the existing.
Yes thank you. Some knowledge, however there is something always to learn. As for the bounce, deflection I feel it would be best to address it as the joist bays are open.
Great Stuff foam construction adhesive is excellent. The guns can be a bit pricey and should be maintained as directed but the performance is well worth the effort.