A Little Bathroom Reno: How to Repair a Damaged Subfloor

It’s been a couple weeks since we shared anything on our bathroom renovation.  To be honest, we’ve been so busy working on it, we haven’t had time to write about it.  Like we’ve said before, not having a functioning bathroom in our house is a great motivator to do nothing but work every spare minute we have.

After demolition, the first step in putting everything back together was to start repairing the subfloor. When we demoed the floor we found old water damage (from leaks that were fixed long before we bought the house) in a couple places.  The Little House was built in 1940, so we were expecting something to be wrong with the subfloor.  The issues we found were relatively minor, so we knew we could fix them ourselves.

Little House Big Heart How to Repair A Damaged Subfloor Repairing a subfloor isn’t a task to take lightly; if not done well, it can cause big headaches down the road.  That being said, if you’re relatively handy (ie. you can use a tape measure, a drill, and a saw), repairing your own subfloor is a pretty easy job that you can definitely tackle yourself (we have faith in you).

Little House Big Heart Subfloor Damage

STEP 1:

The first thing to do when finding subfloor damage is to determine the cause.  Was it termites? Are the little buggers still hanging around? You probably want to call an exterminator either way to make sure that the problem is under control.  If the damage was caused by water, make sure that the leak has been repaired.  If you’re not comfortable with checking out the plumbing yourself, have a plumber come out to make sure everything is hunky-dory.

STEP 2:

Remove the damaged parts of the subfloor.  In our case, this meant just prying up the damaged planks.  If you have a plywood subfloor, you may need to get out a circular saw to remove all of the damaged wood.  Regardless of what type of subfloor you have, make sure you remove everything that looks damaged.  In the end, you should have a nice, clean hole in your floor.

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STEP 3:

Once you have your hold cleaned up, you can measure and cut your new wood to fit.  We used 1×6” planks since that was what our original subfloor was constructed out of, but if your floor was plywood, you’ll want to go back with that.  You may also have to “sister” your joists if they were damaged or if you don’t have a say to screw into them. This means you may have to bulk them up by screwing additional wood to their sides.

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STEP 4:

The last step is fastening your repairs.  You can use screws or nails, but if you’re repairing the subfloor in a wet location, be sure and use coated deck screws or deck nails.  This way, should the area ever get wet again, you fasteners won’t rust.

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Depending on what you’re doing, you may be done at this point.  Because we needed to build up the original subfloor, we went a step farther and laid down 23/32” plywood (why they use such an arbitrary measurement, I have no idea) CDX exterior grade plywood.

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Sometimes it feels like we’re not getting anywhere, but we’ve come so far on the bathroom since we took these photos! In fact, we’re ready for tile!

Have you ever had to repair subfloor damage in your home? Did you do it yourself or call in the pros?