Condo Blues: Master Bathroom Renovation: I Replaced the Subfloor!

Sunday, January 24, 2021

Master Bathroom Renovation: I Replaced the Subfloor!

Removing and replacing the entire master bathroom subfloor is a job that I haven’t been looking forward to and is the reason why we put the renovation off for so long. Everything hinges on the subflooring is cut perfectly to size and level.  Once I removed the old moldy subfloor, I realized that there wasn’t anything to screw the new flooring to around the edges of the room. I can’t leave it this way or the new floor could slope over time and we’d have to start the process all over again. Trust me, once is more than enough! 

how to replace subflooring
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 I  nicked a couple of joists when I was cut the floor to remove it  with my circular saw by accident. This might create a weak spot where the flooring could squeak, crack, or sag or it might not because the cuts are not too deep. 

Do you know how tempting it was to put a skeleton down here for the next person to find when renovating?

 That’s the worst part of the project – trying to figure out if I’m doing enough to fix the problem or not enough. I’ve been checking and double checking my local building code.  I really, really, really don’t want to screw up my house.

The original toilet was installed between two floor joists. The wax ring underneath it was smashed to one side and the floor flange sat at an different angle around the plumbing. The toilet didn’t sit level and this caused one of leaks and eventually mold.  I figured that possibly going overboard with sistering and adding framing  in between the joists to keep the toilet level is better than taking a shortcut and regretting it later. Not to mention, the new vanity is heavier than the old one having some extra support underneath wouldn’t hurt. Wood is cheap. Mistakes are expensive.


how to sister joists

It was much easier to glue and screw the wood frames together in my workshop first than trying to attach them piece by piece to the joists.


Cutting the subfloor panels to size wasn't difficult because before I removed the original subflooring I cut the tile underlayment to fit and to use as a pattern when it came time to cut the new plywood subfloor.  

how to replace bathroom floor

 I also marked where the joists and framing ran on the underlayment so I could transfer the marks to each piece of subflooring which took the guess work out of where I applied the construction adhesive (I used this exact construction adhesive made for subflooring. It is low VOC too!) to the joists and framing and screwed the flooring into place with wood construction screws. (Disclosure: I am including affiliate links in this post for your convenience.)

After I installed the entire floor I held my breath and used a marble to check if the floor was level. The marble didn’t roll up or downhill when I pushed it around the room. I double checked the room with a level like this one. Whew! Everything is is on the level!

With the most stressful part of the renovation finished, the next step is to patch the few gaps I have in the seams, between the floor and wall, etc. with Fix It All (you learn about this patching compound that’s made specifically for subfloors here) that a pro probably wouldn’t have but I do. It is my first (and hopefully my last) subfloor.


Looking for more subflooring tools to do the job right? Check out the following options - and more! - below!

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1 comment :

Sandi Magle said...

That was some pretty shoddy construction under that old subfloor. Great fix and using common sense like adding wood under a 'heavier'sink cabinet is definitely better in the long run. We had great floor beams, but they skimped on the subfloor. We added another 1/2" of subflooring plywood in every room, except for one which will be done next month in our 48 year old house. It is a hint, when you can bounce on your floors and every step squeaks...that something was skimped on. Great post!

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