Subfloor repair around toilet?

b_corwin · 02-02-2011, 01:13 PM

I am adding a new layer of subflooring on top of the existing floor and I want to replace the toilet flange so it sits on top of the existing subfloor. I figured while its open I would replace the trap etc.

The house is 1968 and the joists are ~40" apart and the subfloor is 1 1/8" true 241 t and g plywood. The toilet flange is near one of the joists.

My question is how to procceed? It will be difficult to cut and add bracing since the joists are so far apart. Additionally, the bay that has the toilet flange has a heating duct running through it that lies very close to the bottom of the subfloor.

I was wondering if this plan would be sufficient. I was thinking I could cut a square of subfloor out around the existing flange, large enough so that I could get in there and cut and redo the pipes. After stubbing out the drain, I would then attach new 3/4" ply from the underside of the existing subfloor by screwing down from the top. I would then place the square I removed back down. Sort of like how you might do a large drywall patch, but use strong 3/4" ply. On top of all of this, I am intending to add an additional layer of 5/8" plywood which will be screwed down.

Does this repair method seem strong enough for the toilet?

Thanks much
Brian

**oh'mike** · 02-02-2011, 01:51 PM

That sounds like it would work---the joist spacing sounds all wrong 16" is typical--24" also---

Buy I thought I read 40" --Is that correct? Can you post a picture?

What are you going to install for a finished floor? Tile will be a problem with that span----Mike--

b_corwin · 02-02-2011, 01:54 PM

Yup 40". Its really far. Here is a picture. Floor will be just linoleum. I am putting in a tile shower and am adding in a bunch of cross bracing as shown in the pic.

B

LIHR · 02-02-2011, 02:14 PM

You are going through all that work to patch the sub-floor, just rip it all up, and re-frame the floor, or should I say frame the floor.

That's how bare bone builders do it. That ply is probably rated at 48" OC, but that all depends on use.

I would frame 16" on center and install 3/4" for linoleum, tile and natural stone is a different story and you did mention a tile shower floor.

Take your time and get the floor right, everything will depend on it.

b_corwin · 02-02-2011, 02:32 PM

Not really sure its even possible to add more joists at 16" on center. There is a lot going on under the wall on the right of that image.

My solution for the area of the tile shower was to add those green cross braces to at least reduce flexure under the shower.

Edit and add that after patching the 1 1/8 subfloor I was going to deck over it with 5/8.

B

gregzoll · 02-02-2011, 03:53 PM

You are going to have to use joist hangers, and hang josts to strengthen up the floor. Who built this house, Billy Bob & his cousin Joe Bob.

b_corwin · 02-02-2011, 04:41 PM

Quote:

Originally Posted by gregzoll

You are going to have to use joist hangers, and hang josts to strengthen up the floor. Who built this house, Billy Bob & his cousin Joe Bob.

Are you commenting on the shower area? Or the area under the toilet.

gregzoll · 02-02-2011, 05:43 PM

Quote:

Originally Posted by b_corwin

Are you commenting on the shower area? Or the area under the toilet.

The whole bathroom area, including the rest of the house. This is something that you just can not leave, because the next person that decides to redo the bathroom, may look at it and think that the last guy made changes, and then go after you to pay to have it fixed, because you touched it last.

b_corwin · 02-02-2011, 09:28 PM

Quote:

Originally Posted by gregzoll

The whole bathroom area, including the rest of the house. This is something that you just can not leave, because the next person that decides to redo the bathroom, may look at it and think that the last guy made changes, and then go after you to pay to have it fixed, because you touched it last.

Uh, well redoing the rest of the house isn't quite in the cards.

forresth · 02-03-2011, 02:31 AM

I don't see a problem with joist hanger holding 2x6s across the span were you cut out the opening. cut the opening flush to the edge of the joists so you can raise the cross braces an put in a more reasonable sized plywood and have it come out even. use some 1/4" masonite or whatever to go over the top of the patch and the original floor. some people just keep adding layers to a floor; my kitchen floor is 3" thick

I wouldn't mind some of that headroom back when I redo it.

b_corwin · 02-03-2011, 10:07 AM

Quote:

Originally Posted by forresth

I don't see a problem with joist hanger holding 2x6s across the span were you cut out the opening. cut the opening flush to the edge of the joists so you can raise the cross braces an put in a more reasonable sized plywood and have it come out even. use some 1/4" masonite or whatever to go over the top of the patch and the original floor. some people just keep adding layers to a floor; my kitchen floor is 3" thick

I wouldn't mind some of that headroom back when I redo it.

That is pretty much my plan. Im gonna cut the decking flush to the joists, sister off a few 2x8s and then run cross beams on joist hangers over the opening.

B

**Termite** · 02-03-2011, 05:05 PM

Anything you can do to beef it up will make it better than it currently is. That includes bracing perpendicular to the joists like you're doing.

I would forget the idea of patching the subfloor around the toilet, remove the existing sheathing and install new sheathing. With that awful spacing on your floor joists, anything you can do to have no seams in that sheathing will help to keep that floor as stiff as possible.

bob22 · 02-03-2011, 06:31 PM

Don't include Masonite in the floor; pick a plywood if needed.

bernieb · 02-03-2011, 07:44 PM

Save as much plywood that you can period. Cut your toilet flange pipe below floor, use a rubber repair coupling with stainless steel clamps for the put back. Your new floor joists can be 2x8's,and be sure you treat for termites before the cover up, and insulate your water pipes heavy. Do yourself a favor and put ceramic tile down over concrete board, and use greenboard for drywall. I know you didn't ask .....but hey just a suggestion.

bernieb · 02-03-2011, 07:57 PM

You said (I am adding a new layer of subflooring on top of the existing floor and I want to replace the toilet flange so it sits on top of the existing subfloor. I figured while its open I would replace the trap etc.)

Your water closet has a built in trap, you don't need another trap under the floor. Do you have cast iron or pvc, abs, for plumbing?