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How do you install a bathroom sub floor?

I went to replace a toilet and discovered the bathroom sub floor is rotten.  How do you replace a sub floor?
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Posted 2016-01-23T21:09:44+0000  by flash1 flash1

Hello flash1,

Thanks for your question and welcome to the community!

You've already done considerable work to get the old subfloor out of there to replace it. You'll need (if you haven't yet) to remove the existing flooring. Be aware though that older floors, especially vinyl, may have the presence of asbestos in it 

Asbestos can be deadly if its particles are inhaled, and if the floor is at least 35 years old, then contacting an abatement company is key to ensure it is removed safely. 

You can remove the subfloor once the floor above it is taken off by a pry bar and/or a reciprocating saw. 


To read more about these tools for demolition, please click here for detailed info.

Be sure to wear a dust mask, gloves, and goggles when prying up the subfloor boards so to work safely.

Depending on the severity of the rotting will determine how much and if you want to remove the entire subfloor. For even entire full baths, it's recommended to remove the entire existing subfloor. Especially if the subfloor used was OSB. 

null Oriented Strand Board (Common: 7/16 in. x 4 ft. x 8 ft.; Actual: 0.418 in. x 47.75 in. x 95.75 in.)

During the removal process, be aware of any underfloor ductwork, water pipes, and electrical wiring so you don't accidentally damage them. Inspect any floor joists to see if any damage occurred from them. In terms of subfloor replacement from a leaky toilet, the joists usually hold up well. If you see buckling or damage from the water, you will need to replace them. 

Since this is a bathroom floor, I'd recommend you to replace the wooden subfloor with a 1/2" tile backerboard version. It's impermeable to water if installed correctly, and even if you aren't using tile over it, it makes for the best new subfloor you'll have.

Tile backerboard will greatly reduce and almost guarantee yourself a solid subfloor, so you won't have to ever worry about doing this grisly removal of the rotted wooden subfloor again.

To read more about installing tile backerboard as a subfloor, please click here for detailed instructions. 

For any other questions, please don't hesitate to contact us here.


Posted 2016-01-23T22:07:23+0000  by Joseph_HD_ATL
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