Expert: Dan Griffin - 12/29/2007

Question
I have half inch particle board and half inch plywood on my floors. The particle on top then plywood on the bottom. Can I still put down a hardwood floor or engineered wood with nails or staples? I was told I can't do this because of the particle board even if I have plywood under the particle boards.

Answer
I don't honestly know.  I do know we did exactly that back in the late 60's on some new construction.  Too many years and too many miles to tell if there ever were any problems.

I did some digging and this is perhaps the most telling answer from: <http://www.i-hardwoodflooring.com/woodfaq1.htm>  

Harwood installation FAQ
Can I use Particle Board as a subflooring material?
Recommendation for Subflooring: With 3/4" thick strip flooring use either kiln dried boards of NO. 1 or NO. 2 Common Pine or other dense, Group 1 softwoods suitable for subfloors over wood joists, or exterior sheathing grade plywood. If plywood, 5/8" (19/32") or 3/4" (23/32") performance rated products are preferred. Also, 3/4" (23/32") OSB is a comparable substrate. With 1/2" thick strip flooring use a 3/4" (23/32") subfloor.

The subfloor recommendation does not include particle board. Particle boards, a panel product made of saw dust and or small wood chips, does not hold fasteners properly and so cannot be recommended. The most common occurrence for encountering particle board in a floor system is with remodeling. Particle board or a composition board underlayment is frequently used beneath carpet and vinyl. When these products are encountered, and nail down flooring is to be a replacement, the products should be removed. After removal, inspect the existing subfloor and repair, re-fasten, or overlay to obtain a suitable subfloor. Where removal of the particle board is not an option, the recommended procedure is to overlay it with a minimum 5/8" plywood.

<http://www.vintageflooring.com/installp.asp>  says use of particle board as subflooring voids their warranty.

<http://www.bruce.com/resflram/na/bruce/en/us/article17862.html>
says you must use approved subflooring.  It does not mention particle board, but does certify wafer board.