How to patch bad flooring (mobile home leaky toilet edition)

We’ve all been there, haven’t we? We start out on a project that we’ve been procrastinating on, and just as the project is almost complete, it gets bigger. That’s actually been the whole experience remodeling our 1981 Doublewide. I’m talking, scenes straight out of Money Pit. So, it wouldn’t seem right if plumbing went seamless for me. In this case, the last room to plumb is the main bathroom and low and behold, there is a leak from the toilet inlet valve and around the bowl itself. Gross. If you also have floor repairs to make, or more specifically, toilet flooring repairs to tackle, maybe this will help you get started. Have fun!

Tooling and materials

T square

Safety stuff (ear muffs, goggles)

Measuring tape

Pencil

SkillSaw

Vibratool

Hammer and nails

Screwdriver and screws

Plywood (same thickness as your original flooring)

2x6 (or whatever size joists you have)

Speed square

Chop saw (recommended but you can use skill saw) 

The first thing you will want to do is get an idea of how large the area is that you will need to remove and replace. I chose to first frame up the spot for the new subfloor and then I found more water damage as I actually cut into it. I don’t love having an unsupported hole in the floor but if you can avoid putting weight on it, maybe it would help to first remove the rot. You will want to make this either a square or rectangle shape as it is very difficult to frame up circles and triangles…

 In the first photo you might notice the screws I have dangling down. This was an easy way for me to mark where I would be cutting underneath so I could double check that there was no more damage on the outside of my border. This also gives me points to draw my line for my supports and it’s a lot easier to measure from this point to the other parts of my frame.

Make sure you check that each piece of wood is square. It helps me to get it in place, screw the board a couple of times to hold it there, then nail in the board. You want to use nails as they are stronger for this application. Screws can shear apart of they are side-loaded.

 You want your new flooring to go half over your new supports. You will have parallel joists that run under your floor and each new piece of subfloor will span halfway over the joist thickness so that you have support under each joining piece. If you are not replacing a whole sheet of plywood, you will probably have to build more supports around the joists. You will notice I have the long light colored floor joists running and I attached 4 pieces of wood to the joists going perpendicular. I then finished the frame with 2 pieces of wood running parallel with the joists.

From the top side, it’s easier to see the basic frame shape. We have half or a little more of the thickness of the frame exposed where we will screw down our new board.

 Next step for me was cutting the square hole in the floor. I used my square to lay it out and draw a rectangle. I could not use my skill saw the whole time because the wall was in the way so I had to use my vibratool to finish up. 

 Next, we will be making our plywood patch. First, you want to measure the thickness of your original subflooring. (I wanted to get it a little closer than before since the wood was swollen and I had to read it at an angle. Make sure you don’t include the thickness of the finish flooring on top.

Next, take your plywood and your T-square. I start by making sure my corner that I am going to be cutting from is square.

Once I have an established square corner, measure off of one side and mark it in a few places. Next, line up your T-square with your marks. The T-square will secure to the top of your plywood if your plywood is square. Draw a line all the way down. (You might want to leave a 1/16" to a 1/8" gap in each direction by cutting both sides a little short. If not, you may have to make some adjustments to the hole and/or beat the wood in with a hammer.)

 

Measure and mark your next dimension perpendicular to the first line. You will want to extend both of these lines extra-long as the skill saw blade is only cut through once half of it is through the end of the wood.

 

Next set your depth. With the skillsaw unplugged, adjust the nut and set your blade depth. Easiest to do this with the blade on the end of the plywood and the guard lifted up. Once it’s set, make sure to tighten the nut and ensure it didn’t move.

 

Start your saw with the blade in line to contact the wood. It helps to pull the guard up to get started and once the full blade is in the plywood, the guard will stay out of the way. Make sure to watch the line from the top. Cut until your blade is at least halfway through the end of your desired line. Otherwise it will not cut all the way through the wood.

Next, flip and do the other line.

Fit the patch in the hole. If you don’t give yourself a gap, you will likely have to fine-tune the fit with the vibratool. For some reason, I never give myself much of a gap.

 

Once your plywood looks like it should fit, it may not drop in perfectly.

I usually beat it in from here with a hammer once it looks right. 😅

Out with the old, in with the new!

Next step is to secure it down. For this, I used screws. I screwed in each corner and the midpoint around the perimeter of each corner.

 

If the floor patch is all you had to do, it is done (except putting new finish flooring on top but that’s a later date for me.)

If you are also patching up your toilet hole and plumbing, this instructional is coming soon!