The tile in front of the shower has loosened, and it's obvious that
the wood underneath was rotting due to moisture. Some kind of plywood
maybe. Question now is how to fix it. Several things in play...
1. Best way to remove the rotting wood. The oak flooring underneath is
fine, but the 3/4" ply over that is done. I can just chisel most of
it out, but some areas are still pretty hard. Any shortcuts for
2. Replace with what? I was going to just pour concrete in the whole
removed area. I do have a small tube of Sakrete fast-setting cement
Patcher (Home Depot, I think). Someone told me to put plywood back in
rather than using 3/4" of cement patcher. But I'd prefer not to have a
repeat performance. Will the cement patcher work in that thickness?
3. I should probably waterproof the surrounding remaining ply and the
oak flooring. I was thinking about "Wood Hardener" if I can work up
the nerve to ask for it. ("Gimme some wood hardener...and some
caulk!") What else would seal off the inevitable shower
leakage...some kind of thinned epoxy? Water-base urethane?
4. The floor tiles are an odd size (nothing is going right, so why
that?) It's around 4-5/16" or maybe it's 11cm. Can't find
replacements. Someone advised just doing that section as a different
look. Kind of a step-stone into/out of the shower. But I'd have to get
tile cut then.
5. Any intermediate layers necessary? It looked like the rotted ply
originally had some kind of hard layer on top.
Random comments welcome. I'm sure some of you have had to deal with
*I had a similar problem with a small section of plywood in front of the
tub. However mine was a complete bathroom renovation. I did use Minwax
wood hardener generously. Then I used a floor patch (Henry's from Home
Depot) to level off that section. Then I put down Hardibacker on the entire
floor and walls before tiling. It has been several years and the patch job
seems to be fine.
You can use a multifunction tool to plunge cut out the section of plywood.
Maybe install a piece of cement board instead of putting plywood back.
I think Home Depot stopped selling the Minwax wood hardener and now only
sells water based wood hardener. Try a hardware or paint store.
On Mon, 17 Jun 2013 07:18:44 -0400, "John Grabowski"
Hardibacker is some type of cement board? After hearing 'cement board'
a few times, I'm starting to suspect that there must be a flaw in my
original plan of just filling the hole with a thicker layer of cement.
I think I have some of the older stuff somewhere. I remember it
smelled like a petroleum distillate. Seemed to penetrate pretty well,
but I'm not sure it helped keep the wood from disintegrating.
*Hardibacker is a brand of cement board. There are others such as
Wonderboard. Follow the manufacturers instructions.
The Minwax wood hardener is still available, but not at Home Depot. I have
used it several times on wood that is exposed to the elements and it has
held up fine. The stuff is so thin that it is absorbed into the wood
immediately. Be sure to let it dry for several hours before covering.
Umm, cut off saw with shoe set to proper depth?
Cement backer board. Comes (usually) in 3' x 5' sheets, 1/4 or 1/2 thick.
Screw/nail it down. Leave 1/8 - 1/4" gap where it meets a wall and caulk
fill that gap with silicone caulk. Pure silicone caulk, not "siliconized
something or the other".
If you need it 3/4" thick you could put 1/4 on top of 1/2 or use 1/2 and
build up the difference with mortar as you lay the tile.
I have no idea what "wood hardener" is but if it isn't thinned down epoxy I
wouldn't be using it. I would be more inclined to a liberal application of
wood preservative. In days past, I would have used Cuprinol; now that we
are in the Age of Wusses, about the best would be a borate.
Ideally, the oak floor would have had a membrane, then cement board, then
If you are going to lay tile, you have to cut tile. No big deal, you can
get a perfectly fine "score & snap" cutter for less than $30. Add a stone
to smooth the edges and you are still in Cheapville.
You can also get little tile wet saws with diamond blades for under $100.
I tried using a circular saw (actually a trim saw, I guess). DIdn't
work as well as I expected. Problem may be that there are alternate
areas of soft and hard wood, and some stretches still have the hard
top surface. I'll try again.
I learned my lesson when I tried to use one of the 'siliconized'
things to seal a shower. It was moldy within a couple weeks.
Finally ended up using something from a boat shop: 3M 5200. They
apparently use it under water.
I'll look around for the cement backer board. Is that different from
just pouring a whole layer of cement? (I presume that the surface of
a 3/4" layer of cement would probably get uneven as it cured)
I'll check those. I don't think wood hardener is epoxy, as it's not
2-part. But it is designed to soak into wood. Someone in this thread
mentioned that the new stuff is water-based, and probably not as good.
If I can think of anything that will stick...
I may be able to get the tile pre-cut. I was rather surprised that the
existing tile size is not commonly made. It's about the size of wall
tile, but the surface is different.
That was a very complete reply, DadiOH. Thanks for that!
On Mon, 17 Jun 2013 07:42:25 -0700 (PDT), " email@example.com"
This is an old factory building, probably 100 years old. Oak
floorboards throughout. The bathroom would have been installed
probably 35+ years ago over the original oak flooring.
I've heard of people using some kind of plywood under tile, but it
never seemed like a good idea to me. The result in front of the shower
confirms that. I'll check into 'cement board'.
Thanks to all for the recommendations.
On Mon, 17 Jun 2013 19:37:01 -0700 (PDT), " firstname.lastname@example.org"
Ha! No, it's a typical NYC "Loft building." There are quite a few
downtown. Start off as old textile factories, then renovated by
artists as work spaces, and then inevitably as rents climb, they're
taken over by wall-streeters who want high ceilings. (I'm closer to
the artist category, but I didn't do the original work.)
It sounds like it was a poor installation to start with, and you'll never
match the existing tile. Most bathrooms are a relatively small space. If
you're going to the trouble to repair the tile, you would be better off
redoing the entire bathroom floor. You'll need to pull the toilet, but
that's not a big job. Preferably remove the vanity cabinet too.
Rip up the tile and plywood with flat prybars, bust the tile with
hammers, etc. Make sure you have safety glasses so you don't end up with
a tile chip in your eye. Demo is messy no matter what you do. Sweep
everything up nice, then vaccuum up any remaining dust.
Repair any damage you find to the oak subfloor (if any).
Install a layer of 1/4" or 1/2" hardibacker board so the thickness of the
backer and tile is close to the thickness of the adjoining floor in the
doorway. You'll need a layer of thinset under the hardibacker, then use
the appropriate screws (NOT drywall screws) every six inches. Stagger the
seams, if any.
Use fiberglass mesh tape and thinset mortar to join the seams.
If you want an extra layer of protection, install a layer of Kerdi
Then layout and install your tile using the appropriate notched trowel.
You can rent the tile cutter, or just buy one of those little wet saw's
from Home Depot or Lowes. I only paid $80 for mine and we've used it for
numerous jobs. For occasional home use it's more than adequate.
Give it a day to cure, then carefully clean up any thinset that squeezed
between the tiles. Then you can grout the tile.
Reinstall the toilet with a new wax ring.
Caulk the gaps between the tile and shower. You should also caulk around
the base of the toilet. I've always used regular latex caulk as it's easy
to apply and cleanup with water. A damp sponge makes it easy to get a
professional looking bead every time.
It will be a bit more work than a patch job, but the results will be much
nicer. Besides, you might patch a section now only to have another
section fail a year later.
You should check out the John Bridge tile forum for advice. You can see
photos of my tiling projects at:
On Tue, 18 Jun 2013 14:42:33 +0000 (UTC), HerHusband
I built a towel rack once. ;-)
That sounded so simple when you put it like that, but I imagine that
would be a year's work for me. You're correct that it wasn't done well
to begin with, but I've got to juggle priorities. This started off
smaller...one tile came up, etc. So I'm now up to digging out plywood.
I'm trying to draw the line here. But I'm saving your post (and
others) for the day that I can get the work done right.
Thanks again to all! This is a helpful group.
Yeah, I understand... :) I'm betting it wouldn't take you more than a
few weekends at most. Projects like this sound like a lot of work, but
it's really just a bunch of little things put together. The only real
complication would be if it is your only bathroom, in which case you
might need to rent a port-a-potty or something.
Saturday 1: Measure the floor so you know how much hardibacker, tile, and
thinset you'll need. Then go shopping. I would recommend buying a little
more than you need. You can always return what you don't use, but it
sucks to run short when you're almost finished. When you get home, turn
off the toilet supply, and hold down the toilet lever to empty the tank.
Scoop any water left in the bowl out with a small cup/bucket/sponge or
whatever. Yeah, it's gross, but it's not difficult. Disconnect the water
supply hose, then remove the two bolts that hold the toilet down. Lift
the toilet straight up, being careful not to hurt your back. Store the
toilet some place where it won't get damaged (unless you want to replace
the toilet while you have it out). Stuff a rag in the floor drain to keep
out sewer gases.
Sunday 1: DEMO DAY! Rip out the tile and plywood with hammers and
prybars. Remember your safety glasses! Try not to damage the walls or
you'll have more work to do. Then sweep and vaccuum nicely. Stand back
and admire your work, as you wonder what the heck you've gotten yourself
Saturday 2: Dry fit the hardibacker in the room. If you need to make a
cut, measure and score a line with a sraight edge, then snap the board on
the line. A jigsaw works well for making curved cuts like the hole for
the toilet drain. You'll go through lots of blades though. Once you have
all the pieces cut so everything fits nicely, lift them out and set them
aside (number them if you wish so you know which piece goes where). Mix
up some thinset in a bucket of water. The instructions are on the bag.
Spread the thinset on the floor with a trowel, then use the notched side
to ensure it's the thickness you need. Start in a back corner and work
your way out so you don't get trapped in a corner somewhere. :) Then lay
down the sheet of hardibacker and secure it with screws. Let things set
up for a couple hours, then put fiberglass mesh tape on the seams. Mix up
a small batch of thinset and cover the mesh tape, feathering it smoothly
so you don't end up with a hump.
Sunday 2: Layout and dryfit the tile in the room. Measure and cut the
tile as needed. Once you are happy with the layout, take up the tile and
set it aside. Then mix up another batch of thinset. Spread it in a small
area, screed it with the notched side of the trowel, and carefully set
your tiles into the thinset. Press and wiggle slightly to ensure a good
bond. Plastic tile spacers will help keep everything aligned if needed.
Remember to start in a back corner and work your way out to the door. You
don't want to get trapped in the corner. Cleanup, then stand back and
admire your work. Ideally, come back Monday evening to remove the
spacers and carefully scrape away any excess thinset that squeezed up
between the tiles.
Saturday 3: Wipe down the tiles with a damp sponge, then mix up your
grout. Starting in the back corner again, work the grout into the gaps
between the tiles with a float. Going diagonally helps prevent digging
out the grout you already applied. With a small bathroom floor, you
should be able to grout the entire floor before cleaning. Get a bucket
of clean water and a sponge, then wipe off the grout from the surface of
the tiles. Change the water frequently when it starts to get dirty. When
it hazes over again, go back over everything a second time with clean
sponge and water again.
Sunday 3: You'll probably have a light haze on the surface of the tile.
Wipe it off with clean water and sponge again. If needed, you can use
"haze remover" from the home center. Put a new wax ring on the toilet,
then bolt it back in place. (Remember to remove the rag from the drain
first!) Snug it down, but don't go so tight that you crack the toilet. I
usually tighten the bolts lightly, then sit on the toilet and rock around
a bit to seat it into the wax ring. Then tighten the bolts more if
needed. Gentle, it's not the time to be Mr Muscles. Hook up the toilet
supply, turn on the water, and check for leaks.
Saturday 4: Final touches. Apply baseboard trim, caulk between the tile
and shower, caulk around the toilet, repaint the walls where you dinged
them up, etc. :)
Obviously, I've left out a few small details, but you can find out the
tools and steps you need from any tiling book. The johnbridge tile forum
can be a big help too if you have questions.
Have everything you need before you mix up the thinset or grout. Dry
fitting isn't necessary, but it gives you time to figure out how things
fit and correct mistakes before you get started.
If you can work evenings, or take a few days off work, it won't take as
Whatever you decide to do, good luck with your project!
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