Particle Board Subfloor under wall

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homerstock
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Particle Board Subfloor under wall

Post by homerstock » Thu Mar 17, 2016 11:33 am

Shannon, I'm a fan of your youtube posts. Thanks for all the info.
I have a question about removing a particle board subfloor. I unfortunately have 3/4" particle board subfloor running throughout my house, which sits on top of 1/2" plywood. I have gutted a 2nd story bathroom and need to replace the particle board subfloor in the bathroom because (of course) it is rotten in many spots. The particle board runs under the wall bottom plates. I understand this is bad, but I can't tear down every wall in the house. I plan on cutting and scrapping the particle board off and replace it with 3/4" T & G OBS. However, I do not know how far back I can safely cut back the particle board. Can I cut it back right up to the bottom plate? Or, should I leave about 1-2" of the particle board along the walls to maintain the integrity of the wall (to act as a "footer")? In some spots it is rotten right up to bottom plate and in others it is solid. Where it is rotten I was going to cut up to plate and get out what I can and shove some blocks under it. I am installing a floating vinyl plank floor, so I am not super worried about seams. However, I do need to get the tub and vanity level. If I left 1-2" of particle board I may have trouble getting the tub level because of the unevenness caused by the change in material. PLEASE HELP. I am at a standstill on this project until I can figure out what to do about the floor.


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Shannon
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Re: Particle Board Subfloor under wall

Post by Shannon » Thu Mar 17, 2016 4:01 pm

So if the home is built right they should not be depending on the particle board spanning between joists to hold the walls up and if they were it would have given way by now. Cut right to the plates and tear it out.
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homerstock
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Re: Particle Board Subfloor under wall

Post by homerstock » Fri Mar 18, 2016 10:17 am

Thanks Shannon!

Caleb&Tennessa
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Re: Particle Board Subfloor under wall

Post by Caleb&Tennessa » Wed Jul 25, 2018 4:10 pm

Hi Shannon- first of all, you are my favorite construction teacher on YouTube and my husband loves your advice too! I was so excited to see that you answered questions on this site!

We are at a stand still on our flooring project due to the same issue as above.
House is built in 79' ... 1/2" plywood structural subfloor, with 1/2" particle board substraight on top. We are removing the particle board and laying down plywood substrate for a better quality substraight and longevity overall. We got the center particle board out no problem- then started working on getting it away from the walls to discover that the walls are built ON TOP of the particle board substrate as well as the structural plywood!

What kind of a can of worms did we open?

Can you elaborare on what you think is best to do in this situation?
My husband thinks we need to remove drywall up the wall 12"-18" to hammer in new nails once we finally get the particleboard out and new plywood put in...
Another thought was to avoid this altogether and just cut up next to the wall as close as we could and leave the particle board under the wall plate. This doesn't seem like a good idea to me.

Help!
-Tennessa

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A. Spruce
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Re: Particle Board Subfloor under wall

Post by A. Spruce » Wed Jul 25, 2018 4:44 pm

I would recommend to simply cut the PB along the wall plates and be done with it. There is no need to disturb the wall itself unless the PB is damaged and must be replaced, even then I'd only replace the small bit that is damaged, I would not disturb the entire wall.

Other than where the new plywood terminated against the walls, make sure your joints are over joists. 8-)
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Shannon
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Re: Particle Board Subfloor under wall

Post by Shannon » Wed Jul 25, 2018 10:37 pm

Yup I agree there is no reason to remove the PB from under the walls. Save yourself a ton of work and frustration, purchase a oscillating saw and cut along the bottom plate or flush to the drywall face. Basically you just need to remove it from the drywall face out if you can and that will be fine
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Caleb&Tennessa
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Re: Particle Board Subfloor under wall

Post by Caleb&Tennessa » Thu Jul 26, 2018 8:29 am

Thank you A.Spruce and Shannon!!

This is so relieving to hear. We read some pretty daunting articles online from people who said to remove it... ={

Thanks for specifying which tool to use Shannon. That was our next question!

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