Hello Everyone,
Laying tile for a tub surround. Have assisted others, but first time on my own. . .and can’t seem to remember how to deal with this.
I have set an American Standard steel tub against the studs. Everything is level, square and plumb. I will use 30# felt and CBU’s. The flange on the tub is anywhere from 1/8″ to 3/8″ thick (which includes this black material on the back of the flange which I’m assuming is sound deading material.
My question is when placing the CBU over the tub flange, the surface will no longer be plumb due to the thickness of the tub flange. I desire to use 1/2″ CBU, but should I be concerned about the flange throwing everything off? Would I be better off laying two layers of 1/4″ CBU. The first layer just above the flange and the second layer over the flange (which would keep the walls plumb and square?
BTW: I plan on purchasing an MK370 EXP. Is there another saw I should consider prior to purchasing?
Thanks,
Tark
Replies
Here's one approach: furr out the studs above the tub flange (and all the way to the lid) so that they are flush with the face of the flange at its fattest point. An easy way to do this would be to add 3/8" ply to the walls. Then run a vapor barrier over that and down over the flange, and then install the CBU. Keep the CBU as flat as possible--there's no point in trying to get tile to look flat over wavy CBU. This makes it easiest to get the vapor barrier nicely dressed in the corners. It's a lot harder to do that when the CBU face is flush with the flange, because of the awkward compound folds that need to happen in that situation.
Another approach is just to use 1/2" CBU with the setup the way you have it. The face of the CBU will be out past the face of the flange, so the flange will not affect the CBU or tile. The bottom course of tile cantilevers down off the CBU and covers the top of the flange. Get a vapor barrier behind the CBU.
I have a MK saw based on an angle grinder body.... maybe it's the 370?... works great.
Thanks David. I think I'll use plywood to fur the studs and then membrane with 1/2" cbu.
Tark
tark, skip the cbu's and use Densshield backer-board, no vapor barrier needed,material cuts with drywall tools and face is water-proof and stippled for better adhesion. Seal all butt joints and inside corners with silicon and putty screw heads (use 1 1/4" exterior deck screws fastened with drywall gun) with silicon as well.
Set densshield on studs and bring down to with-in 1/8" of tub rim, fasten and then silicon that joint at the tub rim, apply tile and again come to about 3/16 from tub surface and seal with color matched sanded caulking.
Geoff
You couldn't give me that stuff... it's a gyp board with a 'waterproof' face, and depends on caulk to be waterproof at the corners. If you're going to use it at least take 2 seconds and get a continuous layer of 6 mil poly behind it.
I also agree about denshield being junk.
I use Wonderboard with felt behind it. No biggie.
And ....sometimes I cut some shim shingles to the width of the flange to the tapered end and nail it to each stud bottom on top of the flange.
I then screw the wonderboard over it and about a 1/4" over the tub itself (room for caulking (not grout cause grout always cracks out).
I kind of like that the bottom row of tile is angled out towards the tub....almost unnoticeable.
After the Wonderboard is up and thinset is on all the seams with fiberglass tape it looks like a brick shid house!!!
Theres absolutly no other way I'd go.
Be well
andyThe secret of Zen in two words is, "Not always so"!
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Dave, the manufacturers specs specifically say no VB behind Densshield. I've been using this stuff for 15 yrs. and never had any leaks or failures (I've gone back to check as recently as 2 yrs. ago on a job from 14 yrs. ago!) I have,on the other hand,seen water get to the framing due to the lack of a VB behind cement board and the "failure" of the grout,which allowed water to soak into the cement board and eventually to reach the studs.
This stuff is much better than CBU's and a VB is REQUIRED behind all CBU's!Most guys don't put anything behind the cement board.
As for relying on caulk to waterproof the corners, what do CBU's rely on? thinset? not to mention that since Densshield is easier to cut than cement, you can usually get a tighter fit around your cut-outs, and in your corners, which will aid in keeping out water.
Also, aren't you relying on caulking at the bottom of the backer board? be it Densshield or cement? Since good practice dictates you NOT use grout at this location?
I suggest you drop a piece of this stuff into a bucket of water and see what happens, I think you'll be pleasantly surprised.
Geoff
There are few places with a wider range of qualified opinions than tile materials. I put a poly vapor barrier behind CBU and I think it's the way to go. You can easily wrap a single piece of 6 mil around an entire 4 sided shower and get it tucked into the corners nicely. I use a jigsaw and a handful of blades to cut Hardi and can get cuts as nice and precise as in plywood. I don't agree that good practice dictates caulk at the bottom, because I've seen that caulk ooze out shortly after (6-12 months) and the owner is inevitably furious and the tilesetter cursing as they dig it out and redo it. The majority of tilesetters I've talked to about this recently grout everywhere and caulk nowhere having done both many times. If you have correctly waterproofed your install behind the CBU (and presloped your pan) you don't need the caulk to keep out water. The next shower I do will be CBU over bituthene over 3/8 ply over studs.
I think the tile shower thing is still in a developmental stage.
Caulk and it comes out. Grout and it cracks. Either way you're screwed. Denshield to me is the epitome of the cheapening of building materials to save time and money and utilize lesser skilled labor. CBU is halfway along that continuum, and a full float job is at the right end. I just don't want to trust dabs of silicone to keep water out of the board or out of the corners. A good job needs to last 40 or 50 years. There are almost none of us posting on this who have been in the trades long enough to evaluate the real long-term lasting ability of our work. 15 years is not long enough. Just a couple days ago I saw a guy putting in a Denshield shower and he was then smearing Ultraset all over the corners and the curb. I don't know why you wouldn't just use CBU and a good VB behind it.
Dave, I see your point and I know where your coming from, Alot of the work I've run across has been poorly done , as far as the use of a vapor barrier behind a cbu is concerned, meaning they don't use one.
As to caulk "oozing" out from a joint, I've never run into that problem, BUT, I will say that most guys use way too much of the stuff to begin with. Using hardie IS a good way to improve on the installation, Hardie vs. wonderboard , as you say you can cut Hardie much easier than the Wonderboard ,or the like. And tight joints help to keeep water out of the wall cavity, at least it's better than some of the gaps I've seen that you could drive a truck through.
Caulking should be kept to a minimumand the grout joint at the top of the tub/bottom of the tile should also be kept to a minimum.
As you say, not many other subjects will bring out such varied opinions.
Geoff
Edited 7/12/2004 11:15 am ET by Geoff
Fir out the studs with quarter inch redwood lathe, add a vapor barrier, then CBU. There should be no difference in opinion on this.
Denshield's claim to fame is that it is light and waterproof. Both true, but then you nail through the waterproof membrane. Denshield then says to apply their tape and sealant to re-waterproof the nail holes. Should work in theory.
That being said, I don't like gyp anywhere near water.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
I want to thank everyone for there responses. The redwood lathe sounds like the best idea to furr out the tub, but I read it after I furred it out with 3/8" plywood strips. Tub surround is already covered with 30# felt and the CBU goes on tomorrow.
I had originally used shims to ease the transition from tub flange to studs, furring all the walls for this particular application seemed best. I did return the 1 1/4" CBU screws for 1 5/8" since I now need to go through the additional layer of plywood.
If anyone is interested, I'd be happy to post pictures in a few weeks when everything is done. This was a total bath remodel and was gutted to the studs. Water had leaked past the floated mortar bed and made a real mess of the walls, but it did last for 43 years. . .
thanks again,
Tark
I used Denshield once ... and only once. Next to worthless. Over-hyped advertising. What's the point in using a product that's advertised as waterproof, if you have to silicone all the joints and cuts and screw holes? 30# felt and cbu are a great way to go, but I would use hardie cuz that's me.
I have the MK-370 and find it to be marginal. I started a thread here about 4 months ago and (surprisingly) several people agreed with me: the carriage is very sensitive to torque ... you need to push the left side of the carriage to get a smooth ride. If you push the right side, it binds badly, and if you push the middle it binds a little. The table is not flat, it sags in the middle. Mine sags 3/8" in about 14" which is excessive. It causes large tiles to snap as you near tyhe end of the cut. For 6" and smaller tiles it's not a problem.
If you are a DIY and will use it only occassioanlly, it works well. If you plan to do a lot of tile work, get a Felker.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt