Hello,

Glad I found this site with such great info. I am having 7/16 solid BR-1111 wood staple down installed in the 2nd floor of our house. The existing subfloor is cheap particle board. I know that I need to put down ply-wood but have a couple questions.

1) Should I tear out the existing particle board and replace it with the ply-wood or can I just put the plywood directly ontop of the existing particle board?

2) What thickness ply-wood is recommended?

I am thinking of tearing out the particle board since tacking on the plywood and 7/16" BR-111 over 1/2 inch particle board would make for a very thick floor. Also, if you nailed the plywood ontop of the particle board, wouldn't it also come loose?

Also, anyone know of a good installer in Dallas Area?

Hello all,

Let me clarify my last question. I've read some of the previous posts and sticky posts and it seems like removing the existing particle board and replacing with 3/4" CDX plywood is NOT a good idea, I guess due to structural issues? I would have really preffered doing this to keep the floor height down. Oh well.

So it seems I am left with the option of putting CDX plywood over the existing particle board.

I am still confused as to the width required for the CDX-plywood. The sticky note says to put 1/2" plywood over the particle board, but the BR-111 install guide says 3/4" CDX plywood is preferred and the minimum is 5/8" CDX plywood. This is thicker than the 1/2" plywood recommended in the sticky note. What did I miss?

Thanx for the advice!

A very typical mistake. Folks often get subfloors and underlayments confused. BR-111 is refering to SUBFLOORS. The sticky is refering to UNDERLAYMENTS. They are two seperate things and perform separate functions. But before you do anything, you need to determine IF that particle board you are looking at is a SUBFLOOR or an UNDERLAYMENT. Since it's on the second floor, you cannot see from underneath so do this. Go remove a register. That's the metal grates that cover your heating duct outlets. Now look at the edges of the particle board. Is there plywood BELOW that layer of particle board? If so, you have particle board UNDERLAYMENT and it should be removed. If there is nothing under the particle board but air space and the particle board is attached directly to the floor joists, then you have particle board SUBFLOORING and it should remain. In both cases, installing 1/2" CDX plywood would be ideal UNLESS it turns out you have 3/4" plywood subfloors underneath the particle board. Then, simply remove the particle board UNDERLAYMENT and install your flooring.

The information that you supplied was really great. Our heating/AC vents are in the ceiling for the 2nd floor, but I am sure I can find a way to figure out whether the particle board is a subfloor or not.

If worse comes to worse I can cut off a small piece and look whats beneath it.

Check to see if the PB runs to the walls or underneath them. An underlayment will be cut and ran to the walls using a squared edge product, don't use T&G for that purpose.