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Underlayment layer material (To OSB or not to OSB)

Underlayment layer material (To OSB or not to OSB)

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  #1  
Old 09-11-08, 03:13 PM
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Underlayment layer material (To OSB or not to OSB)

Just reading this forum has got me excited about my home remodel. I am installing 5/8" solid bambo flooring in my house. I pulled the carpet and pad up to find particleboard (the glue and sawdust type) underneath. Everything I have read about this stuff is that it is designed for an underlayment for carpet and pad and not a subfloor, so I crawl under the house and it appears I have a plywood subfloor, therefore the particleboard must be an underlayment (which it is rated for). Also, I have read/been told not use nail down hardwoods with particleboard, so I was going to replace the particleboard with enhanced OSB as the underlayment, either Avantech or Home Advantage, before installing the hardwood floors.

My question: Am I correct in removing the particleboard and then installing an OSB for the underlayment layer and leave the subfloor alone?

I am installing the Home Legends bamboo from Home Depot. The instructions recommend using 15# roofing paper, but I was thinking of using the 1/8" thick 3-in-1 underlayment moisture barrier. Does anyone have any thoughts on this?

Any other thoughts/concerns?

Thanks,
Kevin
 
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  #2  
Old 09-11-08, 03:29 PM
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Definetly get rid of the particle board.

Following the manufacturers instructions to the T. If they said use roofing felt, use it.

You don't need to do anything to your actual plywood subfloor as long as it's FLAT.

Depending on subfloor thickness, you could probably install flooring directly to that, but it's usually always recommended to add a another layer. I would go with either 1/2" or 3/8" exterior grade plywood instead of OSB.

Also, might want to read up on that flooring you are looking at.

http://forum.doityourself.com/showthread.php?t=289485
 
  #3  
Old 09-11-08, 03:56 PM
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HotinOKC,
Thanks for the reply and the link. I have not read through the thread yet regarding the flooring. I will definitely be adding another layer on top of the subfloor once I remove the particleboard due to height matching other floors. My question is why do you recommend going with exterior grade plywood instead of enhanced OSB?

Thanks for the advice so far.

Kevin
 
  #4  
Old 09-11-08, 04:02 PM
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The main thing with OSB is that it can swell more the an exterior grade ply. They have come a long way since they first introduced it, so I wouldn't stress which one to use.


http://www.pathnet.org/sp.asp?id=17336
 
  #5  
Old 09-11-08, 04:16 PM
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Thanks HotinOKC. I actually came across that website earlier in my research. More questions keep popping up. In one small area where I removed some linoleum, the particleboard was replaced with plywood which has some kind of filler in between the boards sealing the gaps. My understanding is to leave a 1/8" expansion gap between the OSB (or plywood) when I lay it over the existing subfloor. Is this correct? or do I insert the tongue into the grove and then attach to the subfloor.

kevin
 
  #6  
Old 09-11-08, 04:27 PM
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Yes, leave a 1/8" gap. This plywood/osb does not need to be tongue & groove (T&G). Your first subfloor layer should be T&G.

When you screw down the underlayment, try avoiding screwing into the floor joists.

No need to fill gaps with anything.
 
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Old 09-12-08, 04:40 PM
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A few questions please?

Originally Posted by HotinOKC View Post
Yes, leave a 1/8" gap. This plywood/osb does not need to be tongue & groove (T&G). Your first subfloor layer should be T&G.

When you screw down the underlayment, try avoiding screwing into the floor joists.

No need to fill gaps with anything.
I just started demo on two rooms which shall become one decent sized kitchen. The current floor (finished basement below) has 1x4s T&G covered by oak hardwood flooring. The hard wood floor is going and I was going to screw and PL400 adhesive either exterior ply or Luan in 1/2" on top of the 1x4 sub floor. Does this sound OK? Why should I not hit the joists with the screws? Confused, TIA
 
  #8  
Old 09-13-08, 08:25 PM
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Is this a nail down floor? If not, you are good to go. If it is nail down, consider going to 5/8" ply.
 
  #9  
Old 10-16-08, 03:01 PM
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Topic revival. HotinOKC, you gave excellent advice before and now I have another question. I plan to use an exterior grade plywood but should I go with A-C or B-C plywood? I don't know if I fully understand the difference.

Also, I plan to use 3/4" plywood on top of the current 3/4" subfloor.

Thanks again for everything so far.
 
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