# Re-tiling a bathtub surround



## BillyB44

I've got a little cabin that has a bathtub with PLASTIC tiles dating from the mid-sixties. Part of the drywall has rotted behind them (see pic) so I plan to pull them off and eliminate all the drywall and put new 1/4" HardieBacker in its place. My question is, can I then just apply thin-set and the tiles directly to this new waterproof backer board? I've seen elaborate methods calling for tar paper + steel reinforcing mesh + mortar bed + float boards + grout, etc. Is it ok to simply go with the right kind of backing board and the right (non porous) tiles? Sure seems easier!


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## drillbit

Oh, that reminds me of my old shower.

Yours actually looks nicer. :laughing:

Mine was that cheap plastic laminate sheet stuff, put up with glue. I also had some rot around the soap holder.

It took about 10 minutes for me to remove the plastic stuff and then about a month to install the new surround. There was a learning curve.

I did what you are thinking about. I put up 1/4 hardibacker board and set exterior brick fasade as my tile. I used exterior grade thinset with some additive mixed in, then grouted, then sealed with exterior grade sealer.

I do have old plaster walls behind the backer board. I did leave a small gap at the bottom (tub) (I think I used a small shim board to keep the gap up until it cured. Then I caulked.

5 years later and no problems so far. (knock on wood)

It was a dusty, dirty mess. Do all you can outside, and in hindsight I would plastic off any adjoining rooms.

Good luck.


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## Nestor_Kelebay

Well, you CAN do what you're thinking, but:

a) 1/4 inch thick Hardibacker board is very thin and flexible. You want something on your walls that strong enough not to bend because if it does, then your grout lines will crack.

b) ceramic tiling is not actually water proof. The glazed wall tiles are impermeable to water, but the grout sure isn't. You won't have liquid water flowing through the grout, but you can have humidity going through it, and that humidity can build up in an enclosed space like a wall. So, you need some sort of waterproof membrane over your wall that you can tile over. A lot of people use a product called Redguard over their cement board. Basically, the Redguard is an impermeable paint that prevents any humidity from the shower area from getting through into the wall. You tile directly over the Redguard.

c) Also, Hardibacker has a lot of sand in it, and it dulls cutting tools very quickly. It's a strong board, but it'll dull any drill bit you use to cut holes through it or jig saw blade you use to cut it. A tile backer board you might want to take a look at is Dens-Shield by Georgia Pacific. It's a gypsum based product, but the gypsum core is made with a chemical that makes it permanently repellant to water. If you put a drop of water on the core, it just beads up like water in an oily pan. Also, Dens-Shield has a plastic coating on one side (the side facing the shower), so I don't even think it would be necessary to use a product like Redguard over Dens-Shield. And, Dens-Shield is as easy to work with as drywall. You just score through the plastic coating, and snap it like drywall.

http://www.gp.com/build/product.aspx?pid=4684

I've tiled 22 bathrooms (more, actually), and I've used Dens-Shield in the most recent ones I've done, and it's a good product. You should be able to buy it at any of the places listed under "Drywall-Wholesale" that sell Georgia Pacific products. Generally, the home centers will only stock it in the 32 inch by 5 foot by 1/2 inch thick size. It also comes in 4X4 and 4X8 sheets and different thicknesses.

If you're at all concerned about the gypsum core not being waterproof enough, phone around to the places that sell it and see if they have a damaged sheet that they can give you a piece of. I had a piece of it submerged in a pail of water for 2 weeks prior to deciding to use it to fix my sister's basement walls after she had a mini-flood in her basement.


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## Nestor_Kelebay

I'd also make sure you put up a real good waterproof membrane (like 6 mil vapour barrier) over your wall insulation and caulk it to the lip of your tub with something like accoustical sealant before putting up the Dens-Shield over top of it. You want to run the Dens-Shield down to about 1/8 inch above the lip of your tub, and have your bottom row of tiles hanging down in front of that lip to come within about a 1/16th of an inch from the tub.

First, put a piece of carpet pile side down in your tub to protect the finish.

Basically, once you get your vapour barrier up, caulked to your tub, your backer board and Redguard or Dens-Shield over that, then you should attach a piece of STRAIGHT wood molding to the wall all the way around the tub. The distance from the top of the tub to the top of that wood molding should be about 1/2 inch less than your tiles are high, so that you'll be cutting about 1/2 inch off the bottom row of tiles.

I prefer to use 6X8 inch tiles because they're the largest size that I can comfortably hold with one hand while back buttering the tile with a trowel in the other. Also, I prefer to set them in the "landscape" orientation. You rarely see that done, so it allows me to get a "custom" look using plain jane tiles. I prefer using plain jane tiles because you can always get 6X8 white, cream or light blue tiles so that you can always fix the tiling even though your original tiles may not longer be available.

Once you've decided on the size of the tiles you're gonna use, and the orientation you're gonna use them in, mark a HORIZONTAL line around the tub walls that's about 1/2 inch (or less) than a full tile height above the tub. (check with a tape measure to ensure that no corner of the tub is more than a full tile height below that horizontal line. Now fasten a straight wood molding so that it's flat top is right on that line all the way around the tub enclosure.

Now, you wanna set your bottom row of full tiles ON that wood molding (so they don't slide down the wall as the thin set cures). Basically, you want to set all your tiles above the wood molding, then remove the wood molding and cut your bottom row of tiles to fit down to the tub. That way, your tiling grout lines will still be horizontal and vertical no matter how crooked or out of level your tub is.

Once you know the tile size you want to use, buy some spacers (typically 1/8 inch wide for 6X8 tiles) and set a row of tiles out side-to-side on the floor with spacers between them. Also do a second row on the floor with the tiles set end-to-end with spacers between them. Using those two rows of tiles, measure from your wood molding to your ceiling to find out how tall a tile you're gonna end up with at the ceiling. If it's anything less than 2 inches, use a row of horizontal accent tiles somewhere in your tiling that's 2 1/2 inches wide so that your top row of tiles will be nearly full height.


To do the wide wall:
Use a large carpenter's square, or a 3,4,5 triangle to draw a vertical line through the "starting point" on your wood molding. Pick the starting point so that the tile width in the corners is about equal at the front and back of the tub. Typically, this will require either a tile or a grout joint in the middle of the 5 foot wall; one of the two. Draw a vertical line through the starting point. Using the end-to-end row on the floor, determine where the edge of the last full tile before the front corner will be. Mark the molding about 1/8 of an inch closer to the starting point near the middle of the wall and draw a vertical line from that mark to the ceiling. Do the same for the back corner.

Using the side-to-side row (I'm presuming you'll be using 6X8 tiles in landscape orientation) on the floor find out where three tile heights above the wood molding will be on the wall. You can use two or three tile heights, it doesn't matter much. Mark a horizontal line on the wall about 1/8 of an inch below where the top of the second or third full tile above the wood molding will be.

Now, use 2 inch wide painter's masking tape to tape off one area to be tiled. Tape off the wood molding, the vertical line through the starting point, the vertical line near the corner and the horizontal line just below the 3 tile height. Spread your thin set onto that masked off area with a V notch trowel, and then pull off the masking tape and you have your thin set perfectly spread over the area to be tiled without having spend extra time spreading it carefully. Now, back butter each tile before setting it in place. The beauty of tiling this way is that even if the thin set on the wall dries up and skins over, the moisture from the fresh thin set on the back of the tile will reactivate it, and the tile will stick just as though the thin set on both the wall and the tile were wet when the tile was set.

When setting wall tiles, I've seen some people hammer on them with their fist to "set" them solidly. That's just dumb. All you need to do to set them properly is to set them in position and then press firmly. That's it. Also, when spreading your thin set on the wall and back buttering the tiles, it's a good idea to have the trowel ridges all oriented in the same direction. That ensures that the faces of the tiles should all be pretty close to flush with one another. When I tile, I trowel the thin set on the wall so the trowel ridges are all vertical, and when back buttering the tiles, I spread the thin set over the back of the tile any old way, and then make a pass from one long SIDE of the tile to the opposite long side. That way, when I set the tile in landscape orientation, the trowel ridges on the wall and tile will be in the same direction and mate together well.

I do not use polymer modified thin set. I've tiled all the bathrooms in a 21 unit apartment block and in 20 years not a single tile has come off of it's own accord. And, the very few I've had to remove have been light fighting with a bear to get off. Using a polymer modified mortar is not going to help your tiles stay on any better or any longer, it'll just make then darn things even harder to get off if an when you need/want to remove one or two for repairs. Besides, after setting your tiles, it's a real good idea to fold a piece of sandpaper in half and run that sand paper through the still empty grout lines to sand any thin set off the edges of the tiles. If you use a polymer modified thin set, then the thin set will dry a lot harder, and sanding the thin set off the tile edges will become a real chore. Pros simply clean off any thin set that's right near the face of the tile and rely on the grout to cover the rest of it, which is reasonable to do, I suppose, but I'm a bit of a perfectionist and I would take the time to remove the thin set from the tile edges.

It's late, I'm tired, but I've tiled lotsa bathrooms and I can probably answer mosta your questions. You know enough about how to proceed for now tho.

For the time being:

a) stick you tub drain stopper in the drain hole and tape it down with masking tape so that it doesn't pop out and fill your P-trap with junk.

b) put a piece of carpet with the pile side down in your bathtub.

c) remove all our old plastic tiles

Is that plaster or drywall behind the tiles?

It's not really necessary to remove all the plaster. If the plaster is in good shape above that rotted out portion, you do have the option of removing the old mastic and tiling over it with thin set. Most people would bark at me for saying that because they think that all the plaster or drywall should be replaced with waterproof tile backer panels, but the way I look at it, if that plaster has lasted this long with only plastic tiles on it, it'll last many times longer with grouted ceramic tiles over it, and that might carry us well into the next century. Most of the water that leaks into the wall to cause damage to the plaster is on the bottom 1/3 of the wall height, and that's gonna be true regardless of what kind of tile is on the wall. When the new tiles need to be replaced years from now, the top half of the wall is still gonna be in decent shape. It's only the bottom half that that the shower water sprays on.

If it is plaster, most likely it'll be washed out in places with voids along the horizontal and vertical joints between your plastic tiles. As you get higher and higher up the wall, the plaster should be in better and better condition.


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## RippySkippy

I'd seriously look into the kerdi product. I've used it and it's a great product...not cheap but it's good.


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## BillyB44

*Wow, what great feedback.*

So I fire up my Mac this morning and what do I find? Some very thoughtful, very helpful feedback. Drillbit, glad to hear it's working well for you after five years. Knock on wood, but not too hard...that's what caused mine to cave in!:laughingAnd out came carpenter ants plus pine needles from wall mice!)

And Nestor, thanks SO MUCH for your time and detailed advice and instructions. You've given me a lot to think about. :thumbsup: I'm copying it and will probably have a few questions as I dissect your words more carefully but just wanted to fire off a big THANKS right away. I did check and DensShield is sold by Lowes in Coeur d'Alene which is about 45 miles from me. Anyway, very appreciative of your time and insights. (Hope you got some sleep.)


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## Nestor_Kelebay

Billy:

I edited (and added some) to that second post, so if you printed it off to read, print off a new version.

Dens-Shield isn't as strong as some other tile backer boards, but it is as strong as drywall, and generally people don't have problems with drywall in their livingrooms, bedrooms, hallways and kitchens not being strong enough to stand up to day-to-day living. Hardibacker is a much stronger board, so if there's any concern about slipping in the tub and putting an elbow through the wall in the process, the option of using Hardibacker remains open. In my building, I have about 15 bathrooms with Wonderboard, 2 or 3 with Hardibacker and the rest with Dens-Shield (which I liked best), and I can't say I've had any problems with any of them.


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## AtlanticWBConst.

BillyB44 said:


> I've got a little cabin that has a bathtub with PLASTIC tiles dating from the mid-sixties. Part of the drywall has rotted behind them (see pic) so I plan to pull them off and eliminate all the drywall and put new 1/4" HardieBacker in its place. My question is, can I then just apply thin-set and the tiles directly to this new waterproof backer board? I've seen elaborate methods calling for tar paper + steel reinforcing mesh + mortar bed + float boards + grout, etc. Is it ok to simply go with the right kind of backing board and the right (non porous) tiles? Sure seems easier!


I haven't read the other replies on this thread, so I might be repeating some information. 

What to do:

1.) *Remove* the tile, and the sheetrock down to the studs (in the shower area). If the insulation is looking wet, moldy, sunken, or deteriorated, *throw it out* and replace it.
2.) Install new *un-faced* insulation.
3.) Install a *poly vapor barrier* over that (onto the studs).
4.) Install *1/2" cement board* over that (onto studs), using the appropriate cement board screws.
5.) *Seal seams* with silicone. Mesh and thinset.
6.) Install new tile work.

DO NOT even attempt to re-use the drywall that is there, or you will end up with the same issues later on.

Best of luck.


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## BillyB44

*Thanks again. I'm off to the store.*

Nestor, again, sure appreciate all the detail and clarity. You obviously know this subject well. The only thing I'm a little unclear about is the horizontal molding that is 1/2 inch (or less) than the tile size. I've drawn a sketch and not sure what I've got wrong... 

I tore off the old tiles yesterday and the existing drywall is next; it's so covered with mastic it'd be hard to get it smooth. I'd feel better going down to the studs and replacing all with DensShield or HardiBacker. BUT, question: the drywall is all 1/4"; should I stay with 1/4" thick backer board to avoid a +1/4" rise/difference that a 1/2" backer board would cause? I like the idea of the added heft 1/2" backer would afford but would it look odd to have the tiles that much more away from flush, if you follow me. Especially on the left wall where the tiles end and the wall continues. Or are there trim pieces that would conceal the discrepancy?

Thanks again so much for your expertise.


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## BillyB44

*Thank U Atlantic*

I will chuck the insulation as part of it looks pretty bad/moldy. Then will tear out old drywall, which is only 1/4" thick. One concern is replacing it with 1/2" new backer board will result in a non-flush edge. Won't that look odd? Should I stick with 1/4" HardiBacker to keep things flush or are there bullnose/trim tiles to disguise the unevenness?

Thanks for your help.


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## AtlanticWBConst.

BillyB44 said:


> I will chuck the insulation as part of it looks pretty bad/moldy. Then will tear out old drywall, which is only 1/4" thick. One concern is replacing it with 1/2" new backer board will result in a non-flush edge. Won't that look odd? Should I stick with 1/4" HardiBacker to keep things flush or are there bullnose/trim tiles to disguise the unevenness?
> 
> Thanks for your help.


Hi Billy,

You need to use 1/2" cement for the framing span. 1/4" will not work. Additionally, keep in mind, that one 4x4 section of installed tile (tile, adhesives,and grout) carries alot of weight. Use the 1/2" cement board. Do not even contemplate 1/4". That product is for use on floor installations, it is not installed on walls as the substrate for tile.

As far as the transition of 1/2" cement board and 1/4" drywall:
If you had 1/4" Sheetrock on the walls and you want to match that transition line up, you can install some vinyl molding along that edge and caulk with latex plus silicone caulking (paintable). Look in the appropriate area at your Big Home Improvement store to find the white vinyl molding best suited for your particular need. It may be one that looks similar to a base-shoe molding, or other style. 

I have had to incorporate similar transitions. Here are pictures of one such transition, to help you get the idea:


















Best of Luck.


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## Nestor_Kelebay

BillyB44 said:


> I will chuck the insulation as part of it looks pretty bad/moldy. Then will tear out old drywall, which is only 1/4" thick. One concern is replacing it with 1/2" new backer board will result in a non-flush edge. Won't that look odd? Should I stick with 1/4" HardiBacker to keep things flush or are there bullnose/trim tiles to disguise the unevenness?
> 
> Thanks for your help.


No, if it were me, I'd still use 1/2 inch thick tile backer board, and then simply tile over the edge of the 1/2 inch backer board on the front and back wall (using thin set to build up your drywall flush with the tile backer) and then just finish the edge of the tiling with a filet of white grout. You do the corners and edges of your tiling with the curved corner of your grout float, so it'll look OK, even if you do it with grout.

(Biggest hunk of people don't know how to tile and as long as it looks good, they will PRESUME it is well done, and there's a good reason for it to be like that. Most of them will think: "Hey, I didn't know tiles came that thick! That's a good idea. I'm gonna use thicker tiles when I do my bathroom too.")

You can see pictures of the bathroom tiling I've done on my web site at:

http://www.ilos.net/~nkelebay

Atlantic Construction's tiling is really nice. I particularily like the idea of using the decorative borders at the bottom and top of the tiling rather than in the middle, which is how everyone typically does it. Being different, in itself, is an attractive trait in most things, I find. The other thing that is well thought out is the fact that the border tiles share the same vertical grout lines with the field tiles. If you don't do that, and have different vertical grout lines for the field and border tiles, it just looks confusing and messed up.

Now, when I first started tiling, penetrating grout sealers weren't very common, and they were of questionable reliability. In my bathrooms I only use acrylic film forming sealers, and that's one of the reasons I like using large tiles; they reduce the amount of grout that I need to maintain. My understanding is that penetrating sealers are reliable nowadays, and they last a very long time. If you use a penetrating sealer on your grout, and I am told they are the best sealers to use, then the amount of grout you have is not nearly as important a consideration as the sealer will last a very long time, so you only have to reseal once every 20 years or so.

In my case, my tiling already has a strong film forming sealer on it, so I would be reluctant to try switching to a penetrating sealer. Stripping off the film forming sealer is likely to leave the grout kinda clogged up on it's surface, thereby interfering with the penetration of a penetrating sealer. When you get to the point of grouting, we can discuss this more. Film forming sealer has lasted over 20 years in my bathrooms with cleaning the tile and resealing every 5 to 7 years or so. It's not that much of a big deal to apply a penetrating sealer to the grout lines in Atlantic Construction's bathroom if you only have to do it once every 20 years, but if you have 21 apartments like I do, then you're doing one every year, and that would get real old real fast. To me, less grout means less maintenance, regardless of what kind of sealer you use. It's just that penetrating sealers last much longer, thereby diminishing the importance of that point.

Another thing I'd mention is that I think I see a bead of silicon around the bathtub spout in Atlantic Construction's bathroom. I wouldn't do that in my bathrooms because whenever I do any soldering on bathroom supply piping, I remove the tub spout and connect my wet/dry vaccuum cleaner to the copper pipe it slips onto. I then open the bathroom tub faucets and the kitchen sink faucets, remove the kitchen sink aerator and slip a plastic bag over the shower head and suck the water out of the supply piping with the vaccuum cleaner. So, if you think you might be wanting to do that, consider putting the silicone around the copper pipe the spout slips onto, or around the threaded fitting the spout screws onto. You can grout around those things, but my experience has been that the grout around those penetrations will usually crack, so you'll be covering over the grout with silicone anyway. Better to just leave out the grout, and use silicone. If you can't see yourself ever wanting to do that, then silicone around the penetrations, and also silicon around the top 3/4 of the spout. Leave the bottom open so that if water does somehow get in, it will leak out.

Also, soap dishes that mount IN the wall are notorious for leaking. If you look on my bathrooms, I tile the whole wall and then mount the soap dishes on top of the tiling, and I have had no problems with having done it that way.

Don't keep thanking me every time I post. I know you appreciate the help, but I also understand that you're still in the decision forming phase where you have to decide a lot of things yourself, and that's gonna take time. As you proceed, post pictures of the problems you're encountering, and I'll be here to give you advice.

You might also want to start a thread in the flooring section cuz the tiling pros are in there. They know better than I. Truth be told, I don't get along with one of them so I let him answer tiling questions in there because he is quick to denegrate any suggestions I make that he disagrees with. (He thinks I know absolutely nothing because I told him I had never done any floor tiling.) However, his knowledge and experience seems to be pretty good, so, why not copy and paste your posts into threads in both forums, and get advice from both of us. That way you get more ideas.


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## Nestor_Kelebay

BillyB44 said:


> The only thing I'm a little unclear about is the horizontal molding that is 1/2 inch (or less) than the tile size. I've drawn a sketch and not sure what I've got wrong...


No, the horizontal molding can be narrower, much narrower. The 1/2 inch involves where you attach it to the wall. If, for example you plan to use 6X8 tiles in landscape mode, each tile will be 6 inches high. You would then attach the wood molding so the TOP of that molding is 5 1/2 inches above the tub. If you chose to use 8X8 inch tiles, you'd attach the molding to the wall so the top of the molding was 7 1/2 inch above the tub. That's because bathtubs aren't always installed level and they can tilt front to back or from side to side. Normally they only tilt 1/4 of an inch or so from front to back or side to side, so the 1/2 inch dimension includes a safety factor in case your tub is installed really out of level.

You set your first row of tiles on the molding so they don't slide down the wall as the thin set hardens. Then you set all the rest of your tiles above that first row. Then, you finally remove the molding and cut your bottom row of tiles to fit down almost to the tub. (leave a bit of a gap between the bottom row of tiles and the tub, 1/32 to 1/16 inch or so.)

If you draw a horizontal line around your tub walls, and find that your tub is very close to level, you can reduce your safety factor and use 1/8 of an inch instead of 1/2 an inch. Even with 6X8 tile, no one ever notices that the bottom row of tiles is only 5 1/2 inches high. They don't look close enough to notice any discrepancy in the tiles, and presume they're all 6X8, including the bottom row.



> I tore off the old tiles yesterday and the existing drywall is next; it's so covered with mastic it'd be hard to get it smooth.


There's an easy way to do it, believe it or not.



> I'd feel better going down to the studs and replacing all with DensShield or HardiBacker.


I agree.



> BUT, question: the drywall is all 1/4"; should I stay with 1/4" thick backer board to avoid a +1/4" rise/difference that a 1/2" backer board would cause? I like the idea of the added heft 1/2" backer would afford but would it look odd to have the tiles that much more away from flush, if you follow me. Especially on the left wall where the tiles end and the wall continues. Or are there trim pieces that would conceal the discrepancy?


See previous post. You can either use grout, or you can do something similar to what you already have in your existing bathroom. Your existing bathroom has black bullnose tiles to cover the edge of the tiling. You can either use cove tiles (which kinda have a cross sectional profile kinda like a quarter round) or you can use narrow border tiles along the edge of your tiling and just thin set them on at a 45 degree angle, or you can use a thicker border tile meant for clay tiles and just paint the thicker exposed edge of the clay border tiles with the same paint as you have on your walls. Or you can use a grout filet as originally suggested, and paint over that grout fillet so no one even notices that step in wall thickness, etc. Finishing the edge with grout as I've done in all my bathrooms is cheap, easy and attractive. And, the first law of ceramic tiling is that if looks good, no one will look any closer than that or care what you did.


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## BillyB44

*Going with 1/2-inch backer*

OK, I get the message. 1/2" backer it is and I'll figure out how to finesse the edges when I get to that point. Which seems like a long time from now. I'm into the demolishing stage still, which is going real slowly, as I need to remove the old drywall very precisely/straight since the 1/2-backer board will obviously need to fill the void left and then become the edge-point of the new tile/trim. ANy tips on cutting and removing the old drywall? I've been using a drill and hand hole saw and drywall knife around window, etc. Slow going. I thought of using (circular saw set shallow) or maybe a jig saw where I could get them to fit. I've also got a little Dremel power tool with a small cutting wheel that might work. What have you used?

Great photos Atlantic; thanks for including that. I see what you mean by the white trim piece. Nice finishing touch.

ANd Nestor, I get the idea of the guide molding piece now. Also, I went to your site and liked your work. Your "Suite 11" is remarkably similar to the layout of my cabin bath, other than mine has a small jog in the right hand tub wall beside the sink.

I'd thank you for you latest help...but you said not to.


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## AtlanticWBConst.

BillyB44 said:


> ... ANy tips on cutting and removing the old drywall? I've been using a drill and hand hole saw and drywall knife around window, etc. Slow going. I thought of using (circular saw set shallow) or maybe a jig saw where I could get them to fit. I've also got a little Dremel power tool with a small cutting wheel that might work. What have you used?


Sharp utility knife will cut it just fine. Especially if it is 1/4" thick like you said....


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## Nestor_Kelebay

What kind of drain piping do you have under your bathroom sink? If it's the old 1 1/4 inch chrome plated style of p-trap, it might be a good idea to remove the drywall on the right side up to the first wall stud to the right of the sink, and replace the drain p-trap. That way you would tile the right wall around the front of the tub down to the baseboard and to the right to form a backsplash over the bathroom sink as well, if you want.

Also, I prefer to tile right to the ceiling, but you don't need to do that. That's something you'll have to decide for yourself. I think it's better to, but it really isn't necessary. It just means that you have a little less wall to paint.

When putting up your tile backer panels, it's kinda a good idea, when one panel is up and the wall above has the bare exposed studs, to slip a piece of 1X3 or 1X4 lumber (or the equivalent size piece of 3/4 inch plywood) and screw it to the back of the tile backer so that half of it sticks up above the tile backer. Then when you put the next panel above that, screw the bottom edge of the panel to that same 1X3. That way, the 1X3 straddles the joint between the panels, so if you happen to have a horizontal grout line fall directly on that same spot, you don't have a weak spot on your wall where the only thing holding that joint together is the fiberglass mesh tape, the thin set in the joint and the grout between the tiles. You'll also have lumber straddling that joint allong it's length between the studs. Most tiling contractors won't do that, but it is a better way to do it.


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## BillyB44

*Molding guide piece*



Nestor_Kelebay said:


> No, the horizontal molding can be narrower, much narrower. The 1/2 inch involves where you attach it to the wall. If, for example you plan to use 6X8 tiles in landscape mode, each tile will be 6 inches high. You would then attach the wood molding so the TOP of that molding is 5 1/2 inches above the tub. If you chose to use 8X8 inch tiles, you'd attach the molding to the wall so the top of the molding was 7 1/2 inch above the tub. That's because bathtubs aren't always installed level and they can tilt front to back or from side to side. Normally they only tilt 1/4 of an inch or so from front to back or side to side, so the 1/2 inch dimension includes a safety factor in case your tub is installed really out of level.
> 
> You set your first row of tiles on the molding so they don't slide down the wall as the thin set hardens. Then you set all the rest of your tiles above that first row. Then, you finally remove the molding and cut your bottom row of tiles to fit down almost to the tub.
> 
> Guess I'm still confused about this. Why not just nail the molding at exactly the right height to avoid all the extra cutting of the tiles below it? i.e. if 6x6 tiles, nail the molding up so its top edge will be at 6" plus enough for that row of grout and the 1/8" or whatever for the silicone bead along the tub? Why place the molding so that it requires cutting all the bottom tiles by 1/2" or so?


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## BillyB44

Good idea about reinforcing the backer board joints. Will do. 

Oh, I went to Coeur d'Alene to buy DensShield yesterday and all they had was DensGuard...? Do you know if it has replaced or is comparable to DensShield?? It is at Lowes, 55 miles from us, so I'm tempted to go with 1/2" HardiBacker which is at a local Home Depot.


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## BillyB44

Ok, I'll just use the knife and lotsa blades. Need to achieve straight edges and square corners too, since this will form the exact bed for the tiles, ya?


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## BillyB44

*Cabin Tub tile Update*

Progress has been slow due to other work, but here's where I am. I wound up with 1/2" HardieBacker which i am about to install once I replace the old insulation and put a vinyl vapor barrier over it. I also need to make the final cut in the old 1/4" drywall to remove the last few inches where the HardieBacker will go. I assume I need to make these cuts precise and right angled exactly. Question: Do I need to use RedGuard too or is the plastic sheet and HardieBacker enough moisture protection? ANd I assume stapling the plastic sheet to the studs is fine. FYI, this tub gets used about two months out of the year then goes into "hibernation."


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## UFoPilot

Yes use Red Guard. However it goes on TOP of the backer board not behind it. You will have: 
a layer of plastic 
a layer of backer board 
a layer of RedGuard
a layer of mastic
a layer of tile
a layer of tile sealer


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## Nestor_Kelebay

> Guess I'm still confused about this. Why not just nail the molding at exactly the right height to avoid all the extra cutting of the tiles below it? i.e. if 6x6 tiles, nail the molding up so its top edge will be at 6" plus enough for that row of grout and the 1/8" or whatever for the silicone bead along the tub? Why place the molding so that it requires cutting all the bottom tiles by 1/2" or so?


Because typically, bathtubs aren't level from side to side or from front to back. If yours is, then you can do that. In my 21 bathtubs, I only had one that was that way. Typically, the tub will be out of flat and level by a good 1/4 inch from side to side or front to back, so the 1/2 inch provides for plenty of leeway in that regard.

Mark a horizontal line around your tub enclosure and measure from that line to all 4 corners of your tub. The closer the dimensions are, the less wiggle room you need in that 1/2 inch dimension.

Never heard of Dens-Guard. If you have to travel 55 miles for it, then I'd opt for the Hardibacker. Be forewarned, though, Hardibacker has a lot of sand in it, so it dulls any metal cutting tools you use on it, like drill bits and such. When I cut it, I use a hand grinder fitted with a thin masonary blade. Or, just use a jig saw, and use more blades, maybe. Or, a jig saw blade with a grit edge rather than teeth.

On most of the bathroom tiling I did with Wonderboard, I pre-chamfered the holes I'd be using to install the tile backer. I drilled a 1/8 inch pilot hole where the studs would be with a masonary bit, and then used one of those "grinding points" made for die grinders with the conical shap to chamfer the hole. Basically, you just put that die grinder point (that will have a 1/4 inch steel shank) in a percussion type hammer drill and grind out a cone at each 1/8 inch hole. In my case, I used stainless steel flat head screws to attach the tile backer board to the studs. The grinder point allowed me to chamfer the holes so that the tops of the screws were counter sunk a bit under the face of the board. Also, cuz Wonderboard isn't the most homogeneous of materials, sometimes the Wonderboard is soft and crumbly where your screw is, so I would fill the chamfered hole with cement based floor leveling compound, and then drive the screw in. That way, if the chamfered hole was rough or out of shape or anything, the cement based floor leveler would accomodate any difference in shape between the chamfer and the screw head.

And, you can sharpen the die grinder points if you have a bench grinder (or anything else). In my case, I'd switch the drill to rotate only and hold the spinning grinder point against the side of the spinning bench grinder stone. The grinding point was spinning in an axis that's 45 degrees from vertical and the grinding wheel is spinning in a horizontal axis, and the result is that as the die grinder point starts to change shape, you can restore the 45 degree cone on it.


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## BillyB44

Ah, I understand the need to accommodate the tub unevenness now. (I put a long level on this one at it looked perfect but will try measuring from a line to all four corners.) I bought the 1/2" HardiBacker and will install it tomorrow. I also sprang for the special screws made specifically for it that are self-threading, moisture-proof and flush mounting. The Hardie info cautions against using power tools due to the silica dust but I bought extra jigsaw blades--and face masks--because I know I'll need to cut around the plumbing, etc.
(When my wife isn't looking.)


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## Nestor_Kelebay

If a 4 foot spirit level tells you the tub is level, then that'll be pretty accurate, say to within 1/8 of an inch over the 5 foot length of the tub.

(The problem is, you can't stretch a tile that much. You can only draw your horizontal line 1/8 inch lower, and trim your bottom row of tiles to fit down to the tub. Having your bottom row of tiles 1/8 inch above the tub in one corner can be covered up with caulk, but it is a nuisance. You'd much prefer to have started 1/8 inch lower, right?)

If you have any clear vinyl hose hanging around, check it accurately with a water level. 

How to fill a hose with water: Wrap the hose around the ID of a pail. REach in and grab the bottom end of the hose and stick a funnel into it. Pour water into the funnel so that the hose fills from the bottom, preventing air bubbles getting trapped in the hose.

Take two sticks of equal length (by ripping one stick down the middle) and hold one stick on the tub and the vinyl hose so that the bottom of the meniscus is at the top of the stick. Have a helper do the same thing at the remaing 3 corners of the tub. If the bottom of the meniscus is right at the top of the stick at all 4 corners, then your tub is indeed perfectly level.

That's a more accurate way to check for level. In my case, I just put the horizontal line 1/2 inch down from a full tile height, and just use a short spirit level to draw my line. That way I don't have to be as accurate and careful, and no one ever cares that the bottom row of tiles isn't the same height as the rest of the rows. As long as the whole installation looks good, that's all that really matters. If the bottom row of tiles is 1/2 inch shorter or taller, no one is ever going to notice except people that do this kind of work, and they're going to know that it's of little importance. People who don't know how to install wall tiles either won't notice or will presume there's a good reason.

LIke I say, as long as the end result looks well done and is attractive, that's as close as the average person is gonna look. You or I would look at those details, but we would at the same time recognize that doing it one way or the other doesn't make it better or worse; it's equally functional and attractive done either way. It would only be a problem if the silicone caulk was 3/4 of an inch thick at one corner of the tub cuz the guy that was tiling didn't check to see if the tub was level and found out the hard way that it wasn't.


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## BillyB44

Thanks for the sequence, UFO. The Hardie company claims no added water-proofing is required with HardiBacker and the smallest amount of RG I can fine is 2 gallons for 39.00. I'd need about 1 pint. Should I still spring for the 39 bucks to be safe?


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## UFoPilot

BillyB44 said:


> Thanks for the sequence, UFO. The Hardie company claims no added water-proofing is required with HardiBacker and the smallest amount of RG I can fine is 2 gallons for 39.00. I'd need about 1 pint. Should I still spring for the 39 bucks to be safe?


$40 is cheap insurance. I used the whole bucket when I did mine. I don't remember it being 2 gallons though. However it was about $40 at home Depot, so I think we are talking about the same size container.


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## BillyB44

Yup, I could be off on the two gallons. It was Home Depot. Guess I'll buy the 'insurance.'


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## Nestor_Kelebay

I would.

The Hardie company is FOS.

If you have a leak through the tiling, say at a grout joint, the Hardiebacker will absorb water. It won't change dimensions cuz of that, but it is possible that any wood it's screwed to will absorb water from the Hardiebacker and eventually start to rot.

Having Red Guard between the tiling and the Hardibacker prevents the backer board from absorbing water in the event of a water leak, and that means the wood stays dry. Dry wood is happy wood.


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## AtlanticWBConst.

If you have Kraft-faced insulation, do not use a poly vapor barrier. It will create an "envelope". Such a "vapor envelope" is not to code, because it creates an area that will trap moisture. If you do install a ply vapor barrier, then remove the old kraft-faced insulation, and install unfaced insulation.


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## BillyB44

*RedGuard it is*

SOunds like a communist faction, but I'll go for it. Also, Atlantic, I put in unfaced insulation so should be ok. Caulking the bottom of the poly to tub was tricky yesterday, but finally got it done. The backer board and tile will obscure the wide bead, thank goodness. I do the HardieBoard today, holding it 1/4" above tub surface, ya?


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## BillyB44

*Gap in backer board*

Quick question. By the time I got the HardieBacker up around the window, there is about a 3/16" gap between two pieces. Do I need to remove them and make the fit tighter, or will the mesh tape and mortar handle this gap ok??


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## Nestor_Kelebay

If you've already bought your thin set, I'd just mix up some thin set and fill the gap with that. Otherwise, you could just fill it with any caulk that happens to be handy that your Red Guard will stick to. It prolly wouldn't stick to silicone.


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## BillyB44

So I got the RedGuard and will apply it tomorrow. Question: must it cover the entire backboard, top to bottom, or can I just do the bottom 1/2 or so where the water will hit? Or will the thickness of the Red Guard (they want 60 mils) make an uneven surface for the tiles if it doesn't cover all of the backer board? If you follow me.


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## Nestor_Kelebay

It's the bottom portion of the wall that you want to ensure is well coated with RedGuard. But, if you've got a 2 gallon pail to do a single bathroom, you're going to have pleny left over.

I'd give the whole wall two coats and then use up the rest of the pail on the bottom 2/3 to 3/4 of the wall. And, put extra coats on the front wall below the shower head and on the side wall at a 45 degree angle (kinda) toward the front wall. Basically, I'd paint the whole tub surround twice, and then put extra coats where it's going to be most needed until you run out of the stuff.

Nope, nuthing is going to show through your tiling.


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## BillyB44

Actually, it's just one gallon, rated at 65 sq. foot coverage, I think (it's down at the cabin right now.) I want to make sure to cover the lower 1/2-2/3 really well and, as you suggest, below the shower head entirely. I was worried there might be a slight unevenness between no coverage and thick coverage areas. I'll do like you say, if I have enough, and bring it to the top of wall as well, but concentrate on the lower portions.


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## marcoj32

5.) *Seal seams* with *silicone*. Mesh and thinset.

What abourt the inside corner wall seams. How do you mesh those corners after the silicone sealer?


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## Nestor_Kelebay

Billy: I'd consider buying another gallon of Red Guard. 60 mil is thin, and it's not going to affect the appearance of your tiling. However, that Red Guard is the main water barrier between your ceramic tiling and the stuff in your wall that will rot and mold & mildew if it stays wet, like the wood and insulation. I wouldn't skim on the Red Guard whatever you do.

Marco: You really can't use mesh in the corners. I wouldn't use silicone in the corners either. I'd just fill those corner joints with the same thin set you intend to use for tiling, and paint the Red Guard over that corner. You'll be tiling into the corners and grouting the corners as well. And, if push comes to shove and the grout in that corner cracks, you can also silicone the corners.

When cutting the tiles to fit in the corners, don't cut them to fit well cuz the grout won't stick to just the glazed surfaces of the tiles. You want to cut them to have a gap between the tiles that the grout can root itself in.

And, if you're concerned about using silicone in the corners cuz it'll eventually mildew, that's not a concern either. There's an easy and VERY EFFECTIVE way of cleaning mildew off of silicone caulk: Just mix up some bleach (straight out of the jug) with baking soda to make a paste, and trowel it onto the silicone with a 1 inch putty knife and spread with a teaspoon. Cover with Saran Wrap and leave overnight like that, or for several days. When you pull the Saran Wrap off and remove the bleach/baking soda paste, your silicone caulk will be white as Manitoba snow. I own a 21 unit apartment block, and that's how I clean my silicone caulk. And it works very well indeed.

The only problem with the above is that the baking soda sinks to the bottom of the paste quickly, so right now I'm experimenting with using VIM "Thick Bleach" which is a gelled bleach and baking soda to make a more stable paste that won't gravity segregate as fast, and that will stick better in vertical corners.


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## BillyB44

*I'm Ba-a-ack, with one last question*

Well, the job is done (see pic--which doesn't quite show spout) but I have a plumbing problem. The tub spout is now too short to reach the threaded pipe end with the added thickness of the backer board and tile. Is there any way to extend the pipe about 1/2" with a screw-on extension or do I have to sweat on a new piece or...???


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## Tudy

Go to the hardware store and get a threaded pipe in the correct length. I have to get a longer one, as well.

Nice looking job!


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## Satori619

Thanks to all of you for your wonderful input, however, I still feel like my question is un answered...

I have gutted my entire bathroom all the way down to the bare studs and cement foundation. Originally there was a shower pan and the walls of enclosure were tiled. We are now going to install a bathtub and tile on up.

Here are my questions:
1. When choosing a tub for this area, our dimensions are 61" x 36". Would it be safe to choose a 60" x 36" bathtub to put into this space?
2. Should we get a bathtub with a flange?
3. If tub has flange, how will the tile be installed? will the mortar be the thickness of the tub flange and then the tile overlaps the flange? If so, then there is still the odd gap between the tile and the tub... How would we deal with this?

Thanks for any input!

~Satori~


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