Covering a bathroom floor - ( our new post)Update and thanks

[tomkaren13]

Need information on possibly covering bathroom floor with plywood.
( 2004 Fleetwood Prowler, ) It has a very small bathroom floor about 2' x 2.5'. Due to what I think are the dreaded sandwich floors, the floor is spongy and I would like to put down a piece of 5/8 p;ywood. The problem wpuld be the toilet flang. Does anyone know of a place to get a longer flang to compensate for the plywood, or could a double gasket be used?
Would appreciate any and all input on this.

[tomkaren13]

Followup - Bathroom floor finished and it came out very good. Thanks to all who helped or tried to help.

Especially thanks to Myredracer who gave us the information about Set Rite Flange Extender Kit and led us to the Sai Seal foam ring.

Since our floor was not rotten we did not have to go that route. Also the original flange was firmly attached to the tank and in good shape the Set Rite kit still worked great.

[Gdetrailer]

myredracer wrote:

Gdetrailer wrote:


Even thought there are "spacers", I would opt for removing the existing flange then when the new floor is laid over top you will install a NEW flange.

Agreed, but how would you remove the existing flange? I tried to do that once and the flange was glued to the pipe down to the tank. I've heard about some flanges being threaded into place onto the pipe but don't know how common that is.

Some flanges are glued to the tank, some may be screwed in like a pipe fitting and some use a rubber grommet..

It would depend on what type or stye you have but in most cases the flange can be cut off with pretty much any "tool" which you can fit on the inside the pipe (Dremel or equivalent) or if you can get to the outside of the flange.

They do make a host of "repair" or "replacement" flanges which can be used with 4" or 3" drain pipe configurations.

So, if the flange is for 3" pipe and you cut the top of the flange off you just might be able to use a flange designed for 4" pipe if it will fit over the outside of the old flange collar.

Worst comes to worst cut the pipe from the inside below the flange and you might be able to salvage enough pipe to glue a new flange on..

Just have to be willing to be flexible and roll with what is there..

A hardware store with a good plumbing department now days is a bit hard to find so in many cases you will have to really hunt around several box stores to find what you need.

In my case I was lucky to not have any rot anywhere near the toilet so I did not have to remove the flange. I did however need to replace my toilet.. That is when I noticed that the flange in my case is firmly screwed down to the floor using wood screws.

Those wood screws in most cases ARE what is keeping your toilet in place and the thin plywood floor doesn't give much holding power to those screws. I would not want to rely on the tank plumbing holding the toilet in place.

[myredracer]

Gdetrailer wrote:


Even thought there are "spacers", I would opt for removing the existing flange then when the new floor is laid over top you will install a NEW flange.

Agreed, but how would you remove the existing flange? I tried to do that once and the flange was glued to the pipe down to the tank. I've heard about some flanges being threaded into place onto the pipe but don't know how common that is.

[Gdetrailer]

If you have a rotted floor placing another "layer" over top of rot fixes nothing. Basically adding weight without strength.

If you are trying to "bolster" a cheaply made floor it is only a bandaid to the problem (and yes, I HAVE walked on some very cheaply built floors)..

Even thought there are "spacers", I would opt for removing the existing flange then when the new floor is laid over top you will install a NEW flange.

The reason for that? Simply put, the original flange is often glued to the tank and is SCREWED down to the floor using wood screws. Adding a spacer only fixes the height issue but at the same time the added height now creates a bigger lever on the flange, wood screws and the tank.. You can create more of a headache down the road..

I would rather do it right the first time and know it won't come back to haunt me later..

[sharker6]

The easiest thing to do is remove any vinyl flooring and delaminated subfloor. Then apply a self leveling compound like THIS Your floor thickness only changes slightly.

[tomkaren13]

Thank you myredcar. Answer right to the point. Your response is much appreciated. Tom

[myredracer]

IF the existing subfloor is okay and just too springy, 5/8" is way overkill. You could use 3/8" plywood and glue it down with PL400 construction adhesive and screw it as well to bring the layers together. 1/4" plywood may work just fine too as long as it's glued and screwed. Some people report that floors feel springy even on new units which is because of the joist span and inadequate subfloor thickness.

If you change the floor thickness and the existing toilet flange remains where it is, it is critical to raise the flange so that a standard rv toilet gasket can be used. Always use a new gasket if you pull a toilet out. Get a "closet flange extender" like in the photo. You can stack these if needed. It's also important that you do not over or under-compress the gasket and maintain the original amount of compression on the gasket. Not sure what the flange extender thickness is (3/8"?), but I would add plywood thickness to match the thickness of the extender. If you add new flooring with thickness to it, like vinyl plank laminate, don't forget to take that into account as well.

Don't use a wax ring unless it's a last resort as it can get too warm inside an RV and can soften the wax too much.

*IF* you have rotten subfloor material, then it's a different story and you have more work to do and you will need to cut out and remove the rotten material. In addition to what Gdetrailer describes, you can install a patch section differently as well. Providing the existing subfloor material is okay, when you cut the old out, leave about 1.5" of overhang over the joists. Then slip 2" wide (or more) strips of plywood under the existing subfloor around the entire perimeter and glue and screw it. The you will have something to attach the new patch piece of subfloor to. This way, you can leave the floor joists untouched. If the subfloor is rotted/disintegrated, as said, you need to fix any water leakage that caused it.

If the subfloor is shot right up to the vanity, if your vanity is not attached to a wall on one end, you may be able to remove it by removing the screws that are typically screwed through 1x1 strips inside the vanity holding it to the wall and subfloor. You may have to remove the shelf by pulling upwards on it to pull the staples away to get access. Removing the vanity may make it easier to fix the floor and also make for a better job.

If you do not have an enclosed underbelly, there's always the possibility of doing some of the repair work from underneath.

[Gdetrailer]

Your NOT going to like what I am about to post..

DO NOT LAY ANYTHING OVER TOP OF OLD ROTTED WOOD, PERIOD.

Your BEST BET is to remove ALL ROTTED WOOD FLOORING.

And yes, you will have a "sandwich", pretty much standard issue on all RVs.

Your top wood is most likely 1/2" or there abouts plywood (could also be "strand board" which is glued and stapled to 2x2 floor joists. There will be foam insulation between the floor joists and the plywood will also be glued to that.

What you need to do is remove the toilet, remove the vinyl floor and then you can assess the amount of damage.

You then need to cut out ALL rotted wood back to the floor joists or as close as possible. If possible cut the floor so you have half of a floor joist for the replacement floor to sit on.

Where ever there is no floor joist for the plywood to sit on you will need to run a 2x2 across from joist to joist.

If you find ANY rotted floor joists you MUST remove all the rotted joist material and sister in new joists (sistering is basically bridging from good part of old joist across to the opposite side with a new piece of 2x2)

Once all rot has been removed and all joists are good you simply will lay down a new piece of plywood of proper thickness INSIDE the cut area. Use construction adhesive and a bunch of drywall screws long enough to go through the floor and into the 2x2s below.

Now to cover any of the cracks between old and new floor you can use fiberglass resin called "tiger Hair". This stuff is a premixed resin with long strands of fiberglass. Mix small batches and spread using a plastic spreader designed for resin work. You don't want to mound it up, only fill in the cracks. If you get too much on you will be GRINDING it off.

Sand or grind off flush with the floor.

Now you can put down new vinyl flooring.

The result will be a floor as good as new.

Do it right the first time and the result will be better than slapping plywood over top of rotted wood.

One should note.. Make sure you find and fix the leak, it would be terrible to have the repair rot out again.