# Replacing upstairs subfloor



## mgrommet (Oct 27, 2008)

I've am planning to do some renovations to the upstairs portion of our home (built in the 80s). The subfloor seems to be in questionable shape (-lots- of creaks and pops) and we are considering replacing all of it, with the intent of eventually putting hard wood down in most areas and tile in the bathrooms.

We've taken a closer look and the subfloor appears to be 1/2 or maybe 3/8 inch osb, with what looks to be particle board as an underlay (same thickness).

At least so far, the creaks and pops are coming from the underlay portion of the floor. There are a few soft areas in the floor too.

First, we want to do this right.
Our current working plan is to put in 3/4" tongue and groove plywood subfloor -- but I'm not clear if this is too thick or too heavy, etc ... and I'm not sure what product and thickness I should use for the underlay. 

Any thoughts? I'm not not the most experienced home handyman, but I'm not afraid to jump in and get my hands dirty either.

I would very much appreciate any advice from those in the know.


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## mgrommet (Oct 27, 2008)

*CORRECTION: Replacing upstairs subfloor*

Just a quick correction -- the pops, creaks, etc seem to be coming from the subfloor, not the underlay -- darn it, got my terminology mixed up a bit


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## JazMan (Feb 17, 2007)

Hi,

The walls of your house are built on the subfloor. You do not want to remove the subfloor unless there's a good reason to. You should check the thickness again. No way the subfloor is as thin as you stated. The particle board does have to go however. 

Get back with the thickness of your subfloor. Also let us know the type, size and spacing of the joists. Measure or take a good guess on the unsupported span of the joists. It might also help if we knew the species and grade too. Also tell us if you're planning for ceramic or natural stone in the bath, and how you plan to install it, and with what.

Jaz


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## mgrommet (Oct 27, 2008)

Attached are a couple of pictures to show the underlay and subfloor thicknesses.

I'm not sure how to answer the type of joists, but they appear to be 2x6 on 16 inch centers 

The subfloor is 1/2" plywood (instead of osb as I previously reported) with the 1/2" particle board crud on top.

When we get around to doing the bathrooms, we're probably going to put down ceramic tile


Thanks for your help!


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## mgrommet (Oct 27, 2008)

Hello?

Jazman, you stll around? It's been a while so I thought I might touch base again...

M.


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## JazMan (Feb 17, 2007)

Yes I'm here again, glad you 'bumped' this back up.

Those pics don't tell me much. Why is the subfloor up like that? Was it cut there? Since it's only 1/2", none has t&g does it? I would leave the subfloor in place and after re-fastening it, install a layer of 5/8" underlayment grade exposure 1 plywood. Normally the underlayment would only be screwed to the subfloor, but since your subfloor is only half inch thick, I recommend installing it as if the 1/2" was not there.

Where tile is to be installed you will then either install a 1/4" tile backer board into thinset mortar, or a product like Ditra, then your tiles. 

I still would like to know the info about your joists subfloor system. I will assumed they are not 2x6, but only you can tell me. This info is kinda important since it is the structure everything sits on.

Jaz


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