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markk96 01-13-2013 05:27 PM

Subfloor Help
Hi Everyone, I am new to this forum.

I am working on my living room and had to pull up the carpet and remove it due to water damage. What I found under it was 1/2 particle board as an underlayment and under that is 1/2 plywood as the subfloor. This house was built in 1976, I have basement access to the subfloor above.

I removed the 1/2 particle board due to its condition. The 1/2 plywood is a little bouncy in spots. What I want to do is put in a Bamboo Floating floor, so I am thinking about adding another 1/2 Plywood underlayment, if I go this route, what do I use as far as nails and screws, do I use glue? Do I screw it to the joists or not? Do I put a paper layer between the two sheets of plywood?

Any help is appreciated. Thanks

joecaption 01-13-2013 05:40 PM

Want to fix it right and once and for all?
If you want it right get rid of the 1/2 and use 3/4" Advantec T X G. Constrution adhesive on the joist and ring shank nails of ceramic coated deck screws to attach it to the joist.
The old subfloor can be cut out with a Tow Kick saw and an ossilating saw or sawsall.
That 1/2" subfloor in not doing you any favors.

markk96 01-13-2013 07:14 PM

Thanks, I will look into that. I know the 1/2 is weak, and I do want to do it right. If I add another layer offset the seams of the plywood, would that not help?

JazMan 01-13-2013 08:24 PM

Joe's suggestion is very good, but sometimes it's not practical to remove the subfloor or it may actually cause other problems. Either method is good.

Years ago homes were built with 1/2" cheapo ply subfloor then covered with a good quality 5/8" underlayment to receive the vinyl floor once the construction mess was over. In the era your house was built most builders changed to a single and thicker subfloor system and let the flooring company prep for the vinyl.

A single 3/4" might be stiffer than two 1/2", but you'd be fine with either. If you just add 1/2" B/C exposure 1 ply, yes of course you have to offset the seams both ways. Do not glue unless you can do a 100% lamination, (very doubtful), and space the sheets about 1/8" Normally underlayment is not fastened to the joists, only to the subfloor, but with only 1/2" subfloor the screws may not bite enough. You won't know until you you do it.

Absolutely no paper or plastic between sheets. Is there a basement, or crawl? Follow installation directions for any moistures tests for the bamboo.


markk96 01-13-2013 09:01 PM

Yes there is a basement with full access to the subfloor above. Nail or Screw? I found Triplay B-C Pine Plywood at Lowes I am thinking about using for this.

JazMan 01-13-2013 10:04 PM

No idea which specific plywood you're thinking about or which way you're going.


markk96 01-14-2013 08:39 AM

I am going to put plywood over what is already there. I do not plan on replacing the current subfloor.

Awoodfloorguy 01-14-2013 08:51 AM

You will be just fine adding a new layer of 1/2" ply. Just screw down the subfloor that is there, then stagger the seams of the new ply making sure you overlap the seams of the existing ply. Then glue and screw the new layer. It's not necessary to add a layer of paper between the 2 layers of ply. Hope this helps.

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