How To Replace Damaged Subflooring Under Toilet - Home Repairs 

I've seen a number of rotted floor under the toilet repairs. This tops them all. The technology moves up quickly and cleanly through the repairs in ways that a video can't. You raised the bar. I must subscribe.

Love how you used CAD to show this. Very cool! You get a great look under the floor too. Thanks!

You got mad computer skills! Thanks!

For a circle, you can use a scrap piece of cardboard, trim nail and pencil. Put ur nail trough the cardboard and mark the radius of the circle with your pencil and put ur nail through your measured radius for your pencil lead to sit in. Attach one hole of cardboard to the center of your circle with the nail and have your pencil led through the other hole and mark your circle.

Thank you! I tore out the floor of master bathroom and was contemplating the best way to do exactly this. Thanks again. You make great content.

How did you get so good at making these videos when you clearly spend so much time in the field DOING THE WORK. I hope I find one of these for all my projects. Thanks a lot!

Thoroughly explained, informative, to the point, and presented in CAD for the best possible visual representation. Thanks!

Excellent video. I have been sitting on the bathroom floor staring at the exact situation. Thankfully I decided to watch a video and found you first. I appreciate you.

That is the best explanation of a home improvement project I have ever seen. Thank you!

Thanks. Just bought another apartment building and 4 bathrooms need this exact fix. Thank you for taking the time to teach.

Nice way to teach buddy , Thanks for the video man

Thank you! You totally saved my turkey on this. I got to this point and had no idea what to do about it until I found your video! After that, it was quick and easy!

Thank you for posting this! I cant afford to remodel my bathroom after I missed a cracked toilet tank that ruined the floor Im excited to learn how to do this on my own!

Thanks for helping me solve my toilet flange problem. You rock man!!

This is exactly what I am doing tonight, screwed the support 2x4s in last night-this video is amazing-thank you!!!

It's good to be Analytical and precise. Thank You Sir!

Outstanding video! Super helpful and well animated. Thank you!

OMG, complete and sensible information where all the others failed! Thank you!

Excellent video! One of the most articulately explaned videos i've seen!!

greg, i am going to build a loft in my shop can you do a video on framing out & supports for a loft ?

Excellent video! Great explanation and illustration.

This video may save us a LOT of $$$. Thank you for sharing your knowledge!!!

Thank you, the video gave me confidence to try it. It was a great help.

Finally something helpful!!

Thank you so much for making such a comprehensive video.

Awesome, helpful video. Thank you Greg!

I wish I would have seen this few days ago It would have made my life easier lol but now I know exactly what needs to be done thank you very informative

Great animation! great narration! well done sir.

Fantastic video! Many thanks!

I did exactly this, I cut the plywood in half and put it under the flange I was looking for a video to see if this was acceptable it just made sense.. good to see I did it right.. thanks.

Thanks a lot man.. really helpful video

I like the annimation, great job!!

Great video

How to put the blocks in place when working from the top?

Masterful! Thank you for sharing your knowledge. Will subscribe!

Great video! Appreciate your time!

thanks for the instruction. I guess i need to first pull the toilet seat up and see if the flange is screwed into any block or if there's any block existing at all. I'm concerned about tearing up the nice finished ceiling in the basement though.

Hi: Early in the video you mention another video about how to install the blocking prior to the plywood patch. I checked both your youtube channel and website to no avail. Can you direct me? Thanks

Thanks! Seems so obvious AFTER I watched it.. but I would have struggled! I appreciate it.

Not putting in blocks was one of the mistakes made when our subfloor broke under the toilet. Using OSB to replace the plywood was another big big mistake. It's not the same height as the old floor. And since the plywood wasn't cut to the joist, it is floating and is squishy in that spot.

Wow! I am happy I found this video. I recently discovered my floor is rotting around my toilet. Not really knowing how it can be fixed, this was helpful in understanding some of the process. Now who would I contact to fix it? I'm not sure where to begin.

So informative. Thank you

This is good!

Like #399. Thanks for the info.

Thank you so much for the assistance. Saved me from having to do it again soon.

Thanks, going to need less plywood than I thought. I agree about cutting around the flange, that's how the floor was cut for my old cast iron flange, and it made a temporary flange replacement impossible without some kind of backing. Thankfully they sell steel backing/brackets that fit around the flange and creates a support, which you can fasten to the subfloor wider around the flange, and then fasten the flange itself to the steel backing/bracket. My subfloor was so bad that I had to temporarily shim the toilet after replacing the flange, otherwise the toilet rocked. I used one of those plastic replacement flanges on a cast iron pipe, which worked okay, but I wouldn't use one again on a cast iron pipe due to height limitations, in this case the flange was too high in its lowest position. Replacement cast iron flanges wrap around the pipe, rather than fitting inside, so there is more freedom to raise the flange up and down. When I replace the subfloor I'm going to get rid of that plastic flange and put on a new cast iron replacement. Should have done that in the first place, but these are things you learn by doing, I guess. This is also probably a good time for anyone to replace the flange, especially if you have an old cast iron one, since you will be able to just place the subfloor over the flange after cutting a hole rather than cutting the board in half or more pieces.

this is very helpful. thank you.

I have to replace my Damaged Subfloor under my toilet but I'm confused about the cut around the toilet drain pipe, should I cut my hole in the plywood around the DRAIN PIPE or the Flange? Any help would be appreciated.........

Thank you so much for this video.

What if the water damaged the floor joist? How would you fix that? Would you just sister it?

Great video! I have to remove our flange because it is cracked through on two sides so I will just cut the hole for the pipe in my new subfloor piece. Glad to see how to do the blocks underneath for great support!

Thank you

Great video! One suggestion I have is that you take your replacement peice and trace it to the damaged floor for a perfect fit. it is difficult to cut a perfect square without a reference edge in the middle of the floor.

Great information, very helpful., thank you! I was about to cut the pipe and reinstall a flange elbow, but this may be more reasonable and appropriate. If my new subfloor is 1/4 inch thinner than the old sub floor, would you suggest I install those support boards 1/4" higher to compensate? Or install the supports and plywood pieces THEN floor leveler after to even it out?

Greg Vancom you rock!!!

thank you!

Good on ya. As in most things in life , there is a fast way and a Correct way , are usually not the same thing . Far to many builders, reno guys , or handyman guys etc , doing it the fast way so they can make more money , and a lot of the time it's with a f--k it ! that'll do ., type mentality . And a lot of this work passes enough to get paid , but fails sooner of later down the road , but what do they care , they're paid and long gone . I've been doing Home Reno for almost 30 years now , and was brought up in a house understanding ... If you're going to do it , do it right the first time . Take pride in what you do .

hello got quick question sir i got cast iron flange but its not that bad in shape but i want to know if could another 3inch flange on top of the cast iron, also should the flange be on top of finished floor or the subfloor? thanks you kinda sir .

I have a rotten subfloor under the toilet and was trying to find out how to replace the east way tell I came across your video plane and simple thanks for the video think I can do this now

I appreciate this.

Great video, concise and simply explained. Thanks so much. Question on the blocking - is there any reason you ran the cross blocks (between joists) horizontally rather than on edge? Would on edge provide more strength/stability or is it not needed? Thanks again for the phenomenal video, this is unreal

Great job on explanation. I just pulled my old toilet out completely by hand. Lol

Perfect!! Exactly what I needed for this weekend’s project! Thank you!!!

Thank you for making these videos!! I am about to try to repair my parents rotted subfloor under the toilet. Extremely paranoid and nervous about being able to do it. Been repeatedly watching this video. Can you quickly explain how the blocking is placed around the pipe? I understand the 2 blocks that connect to both joists. Its the wider pieces. Where do those ge screwed in? Are they also screwed into the joists and added blocks?

Good videoalg

My Home is a 2002 Bought New Double Wide Home, Now the Toilet tank & rotted Floor must be Replaced, My friend is a handy man that will do the job, He has done them a lot before, The Lino flooring must be taken up also & a base must be layed down so we can install those square glue down floor tiles also big Job all around etc. Thanks for sharing your Video etc.

My floor joists are like 5' apart! Theres one joist/main beam about 1' to the right of the toilet flange but to the left is like 3'-4' away. Any suggestions? Thanks

It’s funny because this is the way I did it when I repaired my first one!

Thank you i had rot from a leaking toilet and a guy we had doing it got arrested he didnt cut the hole so this helped. Should have known if i can do it my self i should and it will be done right now and up to code which is needed in a old 70'shome like this

What do you think about using pressure treated plywood in the bathroom?

We had a toilet leak on the second floor which left a small spot of mold on the finished basement ceiling. We had a restoration company come in because we were thinking of going through house insurance. They want to cut out part of the basement ceiling, have blowers going to dry out the ceiling then apply anti-microbial agent. Talking big bucks here. We are planning on renovating that bathroom anyways and will have a new subfloor put down. My question is, when they pull up the subfloor can they not look down on the basement ceiling to access if there is a lot of mold and damage to warrant cutting out the basement ceiling etc and take it from there. My feeling is the water damage is minimal and just want to avoid the extra expense of cutting out the basement ceiling. We did spray 12% bleach on the basement ceiling where the small spot of mold was. Thank you

Do I have to cut a circular hole that is exactly the same size as the pipe? or square with a bigger empty space is fine since I dont have tool

Well I learned more again

One thing i didnt see you explain is if you only cut out the diameter of the pipe, if so the flange will not be flush with the plywood. Or do you cut out the circumfrnse of the bottom of the flange, which is bigger than the pipe itself. So lets say the pipe is 4 inch diameter, well the bottom of the flange is about 4 1/2 close to 5 inches so you can push the flange all the way down flush with the pipe. What do you say about this problem?

Firstly, you’re in a league of your own. The CAD drawings, the explanation, all top notch, and always. But I’m curious as to your suggested orientation of the blocking beneath the subfloor itself. Laid horizontally, (instead of sistered to the joists and blocked perpendicularly), I’d imagine this would afford very little structural support underneath the toilet. Most people literally plop themselves down on toilets. I wouldn’t trust blocking that was laid flat underneath the plywood as shown in this video. It seems like a tremendous amount of strain placed on very few attachment points to the actual structural members below. Please correct me if I’m mistaken.

I love this guy And He sounds like Jordan Peterson.

What if the piece of subfloor I put back in isn’t level with the rest of the floor (I’m in process of making a repair by the shower). Thanks!

So does the bottom of the flange get level with subfloor or finished floor?

I’m currently doing this to a trailer, I had to add a lot of framing.

I love you Greg. Your videos are awesome. Thank you

youtube is much better than the tv show this old house on explaining how to fix stuff like your home or car . exact problem i have to fix today . you can't get much help from the german sports car mechanic at Home depot .

Graphics giving me flashbacks to COD 1

You said to leave a 1/4" gap (at least 1/8th) around the pipe when fitting the blocking and the subfloor. But we have to remember when we go to cut the plywood or OSB board in half (to fit around the pipe) the kerf is going to remove even more material. Is this amount inconsequential (being that it will be only a little more than a 1/4" on each side)? Probably, but I thought I'd mention it. Maybe it would be better to leave only 1/8th inch on the sides which will lose a little length when cutting the board in half and then wait to cut the circle? I guess the right thing to do would be to lengthen the width of the board by the width of the blade to start out with so that both halves sit flush together and against the other boards.

THANK YOU !!!! I have just wasted 3 hrs trying to figure out how to do this before deciding to look on here 🤨

How big are the blocks are they 2 x 4s

Tear back the subloor to the floor joist and that would give better support right

I always thought the toilet flange was suppose to be installed on top of finished flooring for best seal?

Exactly what ineeded

I keep hearing an inch and a quarter? Should my subfloor be that thick before finish flooring????

This is absolutely the best video I have seen that offers THE solution to what seems to be a very common problem. You are an asset to the RU-vid community! Best wishes for your continued success!

Thank you ever so much detail . In time wise how long does it take finishing From taking out and put the toilet right . Approximately please .

Yeah also in real life it's that easy sometimes to get 2 pieces under that with out some force

Why not replace the flange which is probably damaged from the toilet rocking on the rotted floor, so that the subfloor repair can be a solid single piece with a hole (hole saw) so the flange can be installed the right way? Stronger and probably easier.

The flange is supposed to be installed OVER the permanent flooring ie., tile, laminate, etc.. But it rarely is.

Now I need to see how I'm going to replace shower plywood without removing shower drain.

Paint can is exact diameter

I didn't know Jordan Peterson did subflooring tutorials lol

What are you calling blocks? Your video looks like its showing a couple 2x4's and maybe a 2x6 and a 2x8... But either way thats not block. Plus if you split the joists when you cut the sub floor, add a nailer on each side why on earth would you add your "blocks"? Plus if you cut the floor up just cut the elbow off the drain and cut a hole in your new sub floor to fit the drain, add the flange after the floor is down and you dont need any of those crazy cuts. Flange on top of one inch floor with all the screws installed will not result in a wobbly toilet. This video makes this simple project harder then it has to be for literally no reason.

Too much detail

One thing i didnt see you explain is if you only cut out the diameter of the pipe, if so the flange will not be flush with the plywood. Or do you cut out the circumfrnse of the bottom of the flange, which is bigger than the pipe itself. So lets say the pipe is 4 inch diameter, well the bottom of the flange is about 4 1/2 close to 5 inches so you can push the flange all the way down flush with the pipe. What do you say about this problem?