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Unread 01-06-2010, 03:14 AM   #1
ChrisEG
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Stripped bathroom, now questions on rebuild

Hi folks!

I've been reading through a ton of threads, and really appreciate the amount of information everyone is so willing to share here!

I could use some advice on our project - I'll sketch it out first and then ask the current batch of questions.

Bathroom on main floor of house 70yrs old, in Vancouver BC Canada
Stripped down to the studs, tub and sink removed, toilet reinstalled (temp) over new subfloor
Subfloor was planks, has been replaced with 3/4" plywood glued and nailed
plumbing was cast iron, waste/vents/sewer has been replaced with ABS, supply not yet in place but planning for PEX
Brick chimney in one corner, will have one exposed side covered and shared with head of tub wall (incl one shower head on that wall) and other exposed side covered with full height cabinet

Tub plans: acrylic tub (60x32) drop-in style, shower heads at both ends (individual valve shutoffs at showerhead), Kohler Laminar Flow tub filler on wall at foot of tub

Tile plans: concrete backerboard, possibly RedGard, then 12x24 ceramic or porcelain, horizontal orientation and bricklayer ("running bond"?) pattern on tub wall and apron

Question 1: the foot of the tub is closest to the exterior wall, which has been insulated and covered with a vapour barrier. We plan to build a second/fake wall to house the shower/tub valve and one of the showerheads, and don't know whether to cover the vapour barrier with drywall, greenboard, or concrete board before installing the fake wall overtop - is one preferable over the others? Is there any reason to NOT cover the vapour barrier with wallboard of some sort, leaving it open to the plumbing area? We do have vapour barrier on the ceiling, and I'm worried that this wall cavity will become a trap for moisture (where that moisture will come from, I don't know... but I'm a big fan of Murphy's Law).. Suggestions?

Question 2: I've read a bit of the plumbing code, and have seen a reference to multiple showerheads, where the spray/flow from one cannot overtake the spray/flow of the second on its way to the floor drain. Does this apply to dual showerheads in one residential bathroom? FYI - the two showerheads will be sharing the waterflow and pressure from a single pipe coming out of the mixing valve, not plumbed seperately.


Question 3: setting the tub - I've been reading about using mortar to anchor the tub in place, and the advice seems to be to put down plastic, then mortar, then more plastic, then put the tub in. Ours came with a sheet of OSB attached to the feet, and the instructions seem to say that this will stay attached... so do I set enough mortar to support the whole sheet of OSB, but have gaps where the legs (which stick out past the OSB) can come in contact directly with the subfloor (via two layers of plastic).. and then squish the tub to settle it in and get it level? I think I've seen one or two recommendations to fill the tub with water at this point, but most people said no and just to fill the tub during the final caulking of the gap between wall and tub... am I on the right track here?


Question 4: looking ahead to tiling, is there minimum dry times between applying RedGard, then thinset? Our floor plan includes True Comfort radiant heat under tile, and I think the correct order is this: plywood subfloor, thinset, radiant heat wires, leveling compount, thinset, tiles. Does RedGard go in there somewhere? Have I missed anything?

Oh, question 5: (just reread my post, realized I missed something!) Does there need to be a vapour barrier around the chimney, between it and whatever wallboard goes on the tub walls? It runs from the basement (water heater is attached) to the roof, doesn't actually open on the main floor.

Whew! Thanks for reading this epic first post! Looking forward to reading your suggestions, let me know if I've left out any important information!
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Unread 01-06-2010, 06:00 AM   #2
bbcamp
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Hi, Chris!

1) No need or desire to cover the insulation with anything prior to boxing in for the plumbing. Wall cavities should not trap moisture if waterproofed properly and have only one vapor retarder. Use the extra space for more insulation. Defeat the vapor retarding facing on the existing insulation, then fill the cavity with unfaced insulation. The waterproofing membrane for the shower walls/tub surround will be your vapor retarder in this wall.

2) I have no idea of what you are talking about, and I'm a piping engineer. Let's just say that your drain must be sized to handle all the water going into it. A 2" drain is sufficient for your shower. (New plumbing codes allow for a 1-1/2" drain for showers with only 2 heads. If you have body sprays, stick with a 2" drain.)

3) I've not seen one that has a OSB base, but when in doubt, follow the manufacturer's instructions or call their tech support number. More on this later...

4) If you are using heating mats, hot glue them to the floor, prime using the SLC (leveling compound) manufacturer's recommended primer, then pour the SLC. (if using a heating wire, you will need plastic lath.) When cured (cure times are in the instructions, be aware of extended cure times in cold conditions and minimum surface temperatures), apply Redgard as the manufacturer's instruction require for an antifracture membrane. If you are seeking waterproofing properties, compare the two instructions sets, and use the thicker amount. There is a noticeable color change as the Redgard cures, but consult the instructions for cure times. My guess is that you will be ready for a long winter's nap between prepping your floor and tiling.

5) A moisture barrier is required on the shower walls, whether they face interior space, exterior space or a chimney.

Now, let's talk about the tub: I'm thinking that the tub will be installed in an alcove, meaning it will be surrounded on 3 sides by walls. If so, drop in tubs are not the best choice, especially if shower heads are involved. The joint between the tub deck and walls is a bad place for leaks, because you are depending on a bead of caulk to protect the walls from water that will be trapped there. A better tub will have a nailing flange that you can over lap with your moisture barrier and backerboard. If I misread your plans, let me know.
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Unread 01-06-2010, 07:33 AM   #3
Edthedawg
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Welcome, Chris

Bob seems to have your primary concerns covered. Give a pass thru the ol' TYW Whirl Famous Liberry, especially the Shower Construction Thread. Sounds like you have a few oddball things - any 70+ yr old house is gonna have stuff like that. Just keep your plumbing off the exterior walls whenever possible, eh?

And i'd re-think driving two showerheads off a single diverter. Add the 2nd diverter for the far end of the tub. Single supply lines can split in the walls to feed the diverters - better than splitting off a single diverter to feed two heads.

Good luck w/ your project
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Unread 01-06-2010, 01:00 PM   #4
ChrisEG
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Thanks for the speedy help!

Bob, a few clarification questions:

1 - does the additional insulation come in contact with the plumbing, or should there be a space left between pipes and insulation? To connect the vapour resistance, should my poly sheet come from the exterior wall, around the sides of the box, and tuck under the concrete board which will then get Redgarded? Or something else?

2 - we're not doing body sprays, so that's fine, thanks!

3 - good suggestion.. don't know why I always think of the internet before the manufacturer!

4 - I think I'll call the True Comfort folks on this one too, and clarify their installation instructions (perhaps after opening the box - I can't even remember if it is a sheet or wires that we bought)

5 - cool, thanks!

Now for the tub: I forgot to mention that we also have a seperate tiling flange that gets attached to the drop-in tub's curved edge, so if we follow the instructions to secure it properly, then install the concrete board so it hangs over the front of the flange, it should be good, right? Heh, I have more questions about that, so here we go:

A - does the tile extend below the bottom of the concrete board to get as close as possible to the tub line (minus space to squeeze in the caulk), or stay level with the concrete board?

B - I haven't done tiling since helping my dad remove grout from our bathtub when I was 10, and I'm having a hard time trusting that the concrete board and thinset will support the weight of 12x24 tiles rated for floors and walls. Should I relax, or would it be better to source similar tiles that are just wall rated? I do know the trick of using a 2x4 in place of the bottom row of tiles to support the weight of the first row.. any other useful tricks?

C - I'm having a hard time picturing the front corners of the tub: where the tiling flange will end, the tiles of the side walls will continue to the floor, and the tiles of the horizontal edge and the apron will end. Is there some way to make this point where things meet look good, or is it a "cover it with a glob of ___ and call it done" situation?


Ed, thanks for the Liberry pointer, I have poked around in there some already but didn't find answers for my specific oddball questions

I'm not sure that I totally understand what you're suggesting.. does a second diverter mean getting a full second shower setup with temp/pressure control independant of the first shower/tub setup, with its own lines running from the manifold in the basement, or...? And what are the issues/concerns around having both showerheads from a single diverter?

Thanks for the help!
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Unread 01-06-2010, 02:02 PM   #5
bbcamp
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1) Insulation can touch the pipe. Vapor barrier in cold climates is on the warm side of the wall, directly behind the wall board. However, if you plan to Redgard the backerboard, you do not put in a barrier where it will be covered by the Redgarded backerboard. You do not want 2 moisture barriers on the same part of the wall. This is a somewhat confusing issue, so we can discuss it further, or you can search the site for "moisture sandwich."

A) Your tub came with a tiling flange. The day or so before you are ready to install the tub, take the flange out and lay it flat on the floor in a warm room. This will help take the curl out of it. When installing the flange, wipe the tub area with rubbing alcohol on a cloth. Wipe again with another alcohol-soaked cloth until the your wiping cloth stays clean. Let it air dry a few minutes, then peel off the protective paper and start applying the flange. Rub it in to fully bond the surface. Then apply a bead of 100% silicone caulk to the joint between the tub deck and the flange. Let that cure, then push the tub against the studs and hang your backerboard over the flange. You may want to notch the studs so the flange is flush with the front edge, or you can shim the studs so the backerboard hangs straight and is not bowed out. Leave about 1/4" gap above the tub deck, and fill with caulk. The tile can go down to about 1/8" and the gap filled with caulk.

B) The thinset and backerboard (or drywall in other areas) can easily support those tiles. After all, you wouldn't be concerned about a wall full of smaller tile, right? Use spacers to temporarily support each row of tiles from the row below. Pull the spacers the next day.

C) I'm not sure I understand. If the wall tiles extend beyond the front edge of the tub, they will also go down to the floor. This is called a "tub leg." You may have an interesting cut at the top corner of the tub, but strive for a uniform gap to the tub surface. That gap will be caulked, too.

I think Ed is suggesting that having 2 diverters gives you more user options (1 head or 2) and reduces the pressure loss by dividing the flow through 2 valves. The back wall diverter could be plumbed as an on-off valve, whereas the front diverter diverts the water from fill spout to shower head. Or, he was thinking of something else entirely and will straighten both of us out later.
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Unread 01-07-2010, 01:45 AM   #6
ChrisEG
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1 - yup, moisture sandwich is confusing.. and I searched and read a few posts, but there was a lot of talk about steam showers, and not much about exterior walls. A local friend who works as a contractor says that there probably must be a physical wall - no cavity-touching-cavity- due to fire code, and thought that the physical space within the cavity of the fake wall will actually be a very large volume of airspace (fake wall connects to the tub cavity connects to the studs at the other end that connect to the chimney cavity which connect to the thigh bone which connects to the leg bone...) so we shouldn't be overly concerned about trapped vapour.. but I'm a bit skeptical!

Partner is thinking of using regular drywall against the exterior wall, then frame in the box for the valves and plumbing, run the vapourbarrier from the exposed wall up the side of the box and somehow seal it to the concrete backerboard pre- or post-application of Redgard.

I'm voting for at least greenboard against the exterior wall... 'cause I still can't imagine regular dryboard sharing space with plumbing and not having bad things happen!

Thanks for the tiling answers and reassurance. I think I had a breakthrough this morning when I realized that the concrete board would also run down to the floor behind the tub leg, so there's one less surface change than I was imagining. I'm a visual person, and it will prob help me to sketch or make a cardboard mockup to figure this out.

Your description of the back wall having an on/off valve doesn't clear things up for me.. wouldn't it need hot/cold supply and a mixer? If not, then I don't understand how it is splitting off from the main diverter (picturing a Y or T connector just off the valve pointing up) in a way that is different than what I was attempting to describe!

Thanks for your efforts to clarify, much appreciated!
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Unread 01-07-2010, 02:42 AM   #7
ChrisEG
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Oh, forget about the questions regarding the second shower.. we've decided to plumb it seperately and buy just a valve, handle trim, and handheld shower. It will be easier just to bring another pipe up from the basement at that end of the tub rather than futzing it from the other end of the tub!
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Unread 01-07-2010, 05:06 AM   #8
Edthedawg
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You don't even need another pipe up from the basement. just T off the supplies to the main diverter, and wrap those T'd off lines around or below the tub to the other side, and feed the second diverter that way. You were already planning to T off the showerhead output and wrap it around to the other side, this is just the same thing, but w/ two supply lines.

i wouldn't go back to the manifold for something like this. unless it's directly underneath this tub, anyways. I hadda go about 40-50 feet, under the adjacent bathroom, down the basement stairway wall, and snake thru that wall and down to the manifold to drive the supply up to the jacuzzi. We used 2 T's - one to split the diverters and another to feed off to the main tub fill spout, which is a whole separate fixture. (both wall-mounted diverters have their tub lines simply stubbed and capped)
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Unread 01-07-2010, 11:43 AM   #9
ChrisEG
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AH! Now I understand why I was confused The valve we have is a mixer and diverter all in one... a rare thing and we actually hunted a bit for it, because I didn't like having too many different knobs and dials in different spots in the walls. I can see that you were picturing the more common mixer-then-pipe-then-diverter.. and it totally makes sense to put a T in there, if that had been the case.

In our setup, it will actually be quite easy to go to the manifold - it WILL be directly under that side of the tub! Your jacuzzi sounds nice - that's one of the things that my sister has, and I envy: a two-person jacuzzi in her double-wide trailer! Our bathroom is tiny (8' x 6'ish), and the 60x32 tub is pushing it (old tub was 60x30).. the hunt for a sink that was less than 18" was a fun challenge, too, but Home Depot managed to come through with a narrow pedestal that will fit in the width and still let people take a seat!
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Unread 01-14-2010, 03:31 AM   #10
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Overflow drain cover flat, tub wall curved...?

Hi folks,

No plumbing or tiling or flooring to report yet - I've been sick in bed most of the week, and my partner has been doing the carpentry for the tub installation and the closet, and adjusting a light fixture.. mostly one-person stuff, luckily!

We're hitting plumbing this weekend, and are a bit confused about how a "standard" overflow drain fits a tub whose inside wall is curved while the chrome drain cover is straight!

I know the gasket is angled, and that it gets rotated against the outside of the tub to match the tub's slanted walls to the less-slanted overflow pipe... but what happens with the chrome part on the INSIDE of the tub to prevent there being a huge gap along the top? It doesn't seem like a design feature, since the bottom of the chrome part has cutouts to let the excess water flow in...

.. and are two screws at 3'oclock and 9'oclock enough to pull the overflow pipe fitting in against the gasket and in against the tub, or should some sealant be used to keep water from escaping along the bottom edge?

Thanks for the help in advance!
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Unread 01-28-2010, 04:48 AM   #11
ChrisEG
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Hi folks!

Well, we've got the walls up and the tub in and the gasket attached... and now we're onto the floor!

Can you check my order of application, please?

1 - subfloor plywood
2 - thinset
3 - hardiboard 1/4"
4 - True Comfort radiant heat wires
5 - self leveling compound
6 - RedGard
7 - thinset and tiles
8 - grout

Anything look out of place there?

And, I've seen that when we use fibreglass tape and thinset over our Hardiboard joins, that it should then cure for 24 hours... can you tell me the cure/dry times for the other steps?

(I think RedGard is 1-1/2 hours for each of the two layers, right?)


Thanks much!
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Unread 01-28-2010, 05:55 AM   #12
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Cure times for all of your products will vary based on temperature and humidity conditions. In winter, expect longer cure times since temps are low and humidity may be high, or vice versa depending on your heating arrangement. In most cases, waiting longer than the minimum time is a good thing.

Thinset under hardi, no need to wait, you can walk on it as soon as you screw the boards down.

SLC over heating wires, allow a day. However, you must prime the floor before installing the heat mats, then prime the wires. Cure times vary, but allow at least 2 hours. Read instructions for maximum un-covered times, some SLC have them, others don't say. Good idea is to cover with SLC within 24 hours of priming

Redgard, see product instructions. Depends on how much you apply, etc. Color change is best indication of cure.

Thinset under tiles, allow a day for light traffic, i.e. you can walk on it, but you can't move the piano yet. Bigger tiles, heavily modified thinset, allow extra time, i.e bigger than 12", modified more expensive than Versabond.

Grout, 24 hours for light traffic, 3 to 7 days for sealer, depending on sealer's instructions.
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Unread 01-28-2010, 12:22 PM   #13
ChrisEG
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Hi Bob, thanks so much!

I understand all of that, except about priming the floor before installing the heat mats, and then priming the wires. Could you please explain how to do this, and what to use?

Our winter temperature is high, as is the humidity... which is driving the Olympic organizers insane as all of the snow on the local mountains is melting!

Chris
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Unread 01-28-2010, 12:32 PM   #14
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Get your SLC instructions and find what primer they want you to use. Primer makes the SLC stick better to the substrate, and without it, you might as well dump the SLC bags into the dumpster. This step is too important to skip!

The primer is usually applied with a pump-up garden sprayer, but your particular primer may have a different application method.
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Unread 01-28-2010, 12:35 PM   #15
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Will do, thanks!!
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