3/4" Hardwood stapled over chipboard / particle board

I tore up carpeting in a few rooms and I have particle board in some areas. I have read and the concensus is more on the "no" side of installing on top of it. House was built in the late 70's. Under the PB looks like 1/2" plywood (unfinished basement). The PB is in good condition and is nailed down but will need some screws in some areas to remove the squeaks. I would use the std. 15 pound asphalt paper and use 2" staples. My thought is the 2" staples would penetrate the PB and hit the 1/2" plywood as well. It should secure the floor ok enough. As for the moisture issue I will not be installing in a bathroom or kitchen.

Question:

Should I go ahead as is or

1) remove PB and replace with plywood (major task) or
2) put down something like 1/4 plywood or similar.

Thanks! jmac

[cproader]

Welcome to da hood jmac............

You do not want to install a new floor over particleboard......ever. And especially not hardwood. Particleboard is very unstable and the extra labor to remove it at this point is well spent......

[Nick Arrera]

Welcome jmac , agree with CP .. Remove it .. you are just asking for trouble ..

[Floorguy]

With the angle the fasteners are shot in at, they will not provide the holding power needed to secure the flooring. The particle board has no fastener holding power what so ever. You will have a major squeak factory as time passes and the wood moves(shrik & swell)

[Peter Kodner]

No wood flooring should be nailed down over particle board. You will void any warranty (and most are pretty lame to begin with) from any wood flooring manufacturer if you do not take it up.

BTW 5/8 inch plywood is the minimum acceptable substrate if the joist spacing is 16" centers or less. 16' to 19.2 inch requires 3/4 plywood or 23/32 OSB. If your joists are wider spaced, give us the size, type and spacing and the guideline can be given to you.

[Kman]

What everyone else said. Particle board is trash. Literally.

I think when you start tearing it up you'll find it comes up in large sections if torn out the right way. Still a lot of work, but well worth it.

If cost is a concern, in lieu of plywood as your second layer, you could install 5/8 or 3/4 OSB. It has been shown in studies to have the same nail-holding power as plywood, and costs less than half as much as plywood, at least where I buy it.

Whatever you use, make sure to screw it into the first layer, but not the floor joists.

[Peter Kodner]

Kman, disagree with your advise about 5/8 OSB. The Virginia Tech Subfloor Test does show significant loss of holding power in 5/8 OSB over time (stidy did final tests after 2 1/2 years). Is there another study you are referring to?

It also determined mechanical fastening is far better than pneumatic, but I don't see any pulling the power nailers out of the garages

[Kman]

In John Bridge's "Tile Your World", there is an article written by Paul Fisette about 10 years ago. He refers to a study done at the University of Illinois on withdrawal and head pull-through performance of nails and staples in plywood, waferboard, and osb. He found that they performed equal to or better than CD grade plywood.

Structurally, 3/4 OSB performed the same as 1/2 plywood, but since we were talking about a wood installation which has a much higher tolerance for deflection than, for expamle, a tile installation, I didn't feel like structural integrity was a concern for jmac's installation. Of course it wouldn't hurt to use the 3/4 OSB, it would just add a little more height to the floor.

*I hope I didn't violate any copyright restrictions by referring to the article in John's book. While I didn't quote the article verbatim, I believe I got the general idea across. Slash it if you need to, T.

[TFP Admin]

No, no, you did fine, Kman. You could even link to that article, if you know where it's at. References and excerpts are good, copying whole articles are not so much.

T

Many thanks! I took the liberty of starting the tear-out even before I read everyone's reply. Such a royal pain getting that stuff out. Its all hand nailed and no glue but we found prying up all the nails first made removal easier/cleaner than prying/destroying.

The subfloor looks like 1/2 or 5/8 plywood 16" on center. The floor is a bit bouncy between the joists so I may want to consider the plywood instead of the osb.

Ok, so what is the verdict on what to put down?

Also, should I screw it to the first layer with short screws or long screws all the way into the joists? This was in response to kman's statement.

Many thanks! jmac

[Peter Kodner]

It would be great to get a link to the report if any knows where it is. The Virginia Tech report is a testing of holding power of 2 1/4 strip in various subfloors with both cleats and nails. A "must" for wood installers. Available in pdf at the NOFMA website.
Here is the link: http://www.nofma.org/Portals/0/Publi...t%20Report.pdf

[Kman]

No matter what you use, osb or plywood, the screws should only be long enough to go through both layers of subfloor, not the joists. No glue between the layers, and deck screws every 8" through the field, and every 6-8" around the perimeter.

As far as a link to the study, I don't know where it might be posted, other than on John's website. I read about it i his book "Tile Your World".

Just to clarify, the writer recommends plywood instead of osb for tile installations. However, since this is a wood installation, and a 2" cleat or staple will penetrate both layers of subfloor, I'm still convinced that osb is sufficient for this application. Other than the additional cost, there is certainly no downside to using plywood, though.

[Danny Ferguson]

Kman, why do they want the screws to go into the floor joists?

[Kman]

the screws should only be long enough to go through both layers of subfloor, not the joists.

They don't, Danny.

[Jerry Thomas]

The easiest method i have found for removing PB is to use a long catpaw (nail puller) and get the nail heads up about a 1/4" then take a 36" Gorilla Bar and lever the nails out. hardly any effort that way and just remove the whole sheet at once.

I replace the PB with a BC grade plywood.... either 5/8 or 1/2 .... most times I go back with the same 5/8". Before you do anything else re-nail the 1/2" CDX and check for flatness,.... make any needed corrections before the new plywood goes down.

Install the plywood in the same direction as the 1/2" CDX sheathing you have for a subfloor. Keep all seams offset and staggered and nail/screw it off every 6-8". As Kman said..... do not locate the floor joist and try to hit them ....... ignore the floor joist for this task.

I use squiggles of yellow wood glue underneath the new underlayment "if" I am going to install wood. If I am putting in tile I do not glue here.