Nailing Bruce Unfinished With An OSB Subfloor


I will be installing Bruce unfinished 3/4″ strip flooring this weekend. My subfloor (above grade) consists of 23/32 Sturd-I-Floor OSB over 24″ OC joists. I’ve heard of problems with nails not holding in OSB all that well.

My questions are: 1) Should I use barbed nails or staples? 2) Is there any advantage to putting down a thin layer (1/4″) Plywood on top of the OSB to better hold a nail/staple? 3) Is there anyway to both nail AND glue down the hardwood boards? If so, do I forget about using 15lb felt paper or glue that down as well?


Dear Derek

There are so many problems with OSB that I cannot even begin to describe them here. I just make a mention of it in the strip and plank floor article in the Hardwood Authority section of this site. And the minimum fastening surface for the hardwood you are using over these long spans of 24″ is 1″ of plywood. So seeing that your subfloor is less than useful as a nailing surface, you should add at least 1/2″ plywood to get a bit more stiffness, and if you can stand the height 5/8″ plywood would be better. The 1/4″ material you refer to won’t do a bit of good.

That all said, I felt so strongly about this negative effects of this product, I wrote another Strip Floor article, meant to influence the minds of the professional floor installers. I don’t care to influence Bruce they may be stuck in their past habits. I devoted about a third of this article to the pitfalls of this material.

And as to the nails vs. staples be sure to read my article in the Floored News about this issue. Suffice to say use a pneumatic floor nailer. These are all not just my opinions, but a close review of the facts from many learned sources, and my own experience with squeaky OSB floors, and the damage that floor staples cause to hardwood floors.

Oh, and only NAIL down this floor using the proper floor nails every 6-8″, never glue down this type of floor, it will prevent normal seasonal movement. And the felt does no good. A thick subfloor will prevent the 2″ flooring nails from penetrating the subfloor. The go in the wood 7/8″ on a 45 degree angle. So that is why a 1″ or more subfloor over a well ventilated crawl space is so important.

As always your Most humble servant, Joseph, the Wood Floor Doctor.