Am I in trouble? Damaged floor under shower pan.

I knew there was water damage. The house is thirty years old with the original shower tile. It spent several years as a rental then I bought it with mostly cosmetic changes. I fixed some tile in the other bathroom and didn't think much about the master bathroom, loose tiles and all.

I've decided to retile the master bathroom along with the floor (i.e. couldn't. ignore the problem anymore). I removed all the tile and rotten drywall down to the studs. The studs looked great and I thought I was out of the woods.

I removed the fiberglass shower pan so I can install a new Swanstone shower pan. Unfortunately, the drywall was not the only damage. The floor beneath is rotted and needs to be replaced.

The layout is as such: To the left is a closet wall (with plumbing) just out side the bathroom entry. Behind the far back wall is the master bedroom. To the right is the end of the floor – top level of a tri-level so the floor stops there. The flooring on the other sides of the shower walls look very good. Some small stains on the bedroom side, closet looks fabulous.

The floor joists run left to right with two underneath the shower floor. You can see one just under the "inspection hole" I could access the drain area under the floor via a dry walled access area in the garage below.

I'm thinking I'll just replace the floor and run cut 2x10s or 2x6s front to back square up the nailing surface. I'm a bit worried about the remaining floor under the wall base that will be left over. I'm also worried about the back wall. Will I need to add a left right support before the wall or will front to back suffice?

Is this a good idea? Do you all have any suggestions? Or am I in trouble and looking at a messy, expensive fix? I'm a fairly advanced intermediate DIYer

I'd cut out the bad sections, put in blocking so the ends of the pieces will have support, then put the new stuff down. Note, it is best if the ply spans 3-joist bays to stabilize it.

I strongly suggest you check out www.johnbridge.com for tiling and prep help. They've got a structural engineer and tiling experts that can guide you through this...they get a lot of traffic and have a good library to help you out with in addition to specific advice.

Before tiling, you really want to run your structure through a deflection calculator to determine if your joists/span will support tile. Note, if you decide to go with stone tile, it needs to be at least twice as strong as it does for ceramic. They've got an on-line calculator you can use to determine your structural statistics. Good luck.

Last note, some older showers used a 1.5" drain line...today's code requires 2", so you may need to do some additional plumbing work while you've got the floor up.

Jim,

Thanks for the super quick response!

I'll definitely check out the John Bridge forums. I've been lurking there too.

The floor tile area is very small. 3' x 5' outside the shower and 6' x 4' in the vanity area with a door/wall in between. Would a small area like this benefit from structural analysis?

Drain pipe is 2", thanks for the advice.

Tom

A common misconception is that the size of the floor you are tiling doesn't depend on the structure underneath; it does, radically.

The deflection calculator requires knowing the width, depth, species of wood, and the length of the unsupported run (i.e., from either an outside wall, a structural wall (underneath the floor), or a support beam). It does not matter if the area you are tiling is 1 sq ft or huge...if the floor can deflect, and it does that between the supports holding up the floor is enough, the tile will fail.

I have recently completed a similar repair / rebuild of a 34 x 60 shower area with failed shower floor tile, cracked mud deck, leaking lead liner and severly rotted sub-floor.

The rebuild was supervised by a 30+ year tile pro:

I did the following:

Cut out sub-floor with recip saw as far back as possible to the base plate.

Legered in 3/4 plywood with galvanized deck brackets mounted from the underside of the base plate. (Screwed in) 6" wide brackets at 1 foot intervals in order to support the unsupported edges of the new floor, then shimmed level and screwed down the 3/4".

This all worked very well to support the new curb , pan liner, mud deck and final shower floor tile.

My advice- if this is a home you live and in and will stay in be brave and go the extra miles with a custom built shower incl. mud slope floor finished with tile. Caution though! No room for short cuts due to the damage that could result with leaking from a second floor.

new plywood,....

you are installing a shower pan with a liner....correct??



if you are installing a shower pan with a front threshhold

all you really need to do is simply lay a piece 3/4

plywood into that area right over the top of that old plywood.....

and end it under the new threshhold....


nail it down firmly and you will have a very solid floor

it really wont matter and I doubt 3/4 inch you will feel the difference in height in

the new concrete floor either......

if you feel the need to cut out that sub floor out go for it, but I dont

think its worth your time and effort....


I have seen much worse looking floos than that one

I'm sure it's hard to tell from the pics, but I was thinking that the whole area (except for the hole) was incredibly clean for a 30 yr old house.