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kl
04-11-2011, 01:41 PM
Hi,

Our master bathroom is being partially remodeled because of water/mold damage in the tub/shower surround. The house was built in the 70's, so the old tile was mounted on regular sheetrock. The old stuff has been removed by mold remediators, and the wood framing has been sanded and cleaned of mold. Our tiler will be installing 13 x 13 porcelain tile and I think he is using Permabase board, with 2 coats of RedGuard. One wall (the end of the tub wall) is an external wall and has old paper faced insulation.

I have read other threads that refer to cutting slits in the paper facing every 4 inches or so with a utility knife to avoid a moisture sandwich with the RedGuard. The old paper facing already has a few prior slits and tears in it.

My insulation questions are:

1. When I mentioned to our mold remediator (who is an air quality specialist also) the idea of cutting slits in the insulation, he didn't like the idea of messing with the fiberglass insulation at all, as he says it is as bad as asbestos. He wasn't that familiar with the moisture sandwich methods. Is it a case of choosing the lesser of 2 evils (stirring up fiberglass by slitting, or not slitting and risking mold)? Is there a particular way to make the slits to avoid disturbing the fibers?

2. Is the "every 4 inches" a correct spacing for the slits? Do I measure out 4 inches from the stud to make a cut, then 4 inches down to make another cut? (There are a few existing tears and cuts already in the paper facing. And, it is open on the sides to some degree, next to the studs.)

3. How big of a slit do I make?

A couple of other questions:

1. One end of the tub (where the fixtures are) borders the bedroom wall, and the long wall of the tub borders the master closet wall. Sheetrock was removed about half way up the closet wall and the bedroom wall in the mold demolition (the walls on the other side of the framing from where the cement board will be). So, that sheetrock (on the bedroom and closet side will be partially replaced). Should we just use regular sheetrock there or greenboard? Because of the cement board/RedGuard, and the framing in between, I am assuming that it is unlikely that that sheetrock would get wet from general shower use, unless there is a pipe leak on the one wall.

I will try and upload some photos.

Thank you,
Kim

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bbcamp
04-11-2011, 01:50 PM
1) I don't think fiberglass dust is in the same health risk category as asbestos. You certainly want to avoid breathing it, but in this case, it would be a short term exposure since you can make your cuts just before setting the backerboard in place.

2 and 3) A 1" cut every 4" or so both vertically and horizontally will be fine. Water vapor will find a cut and be on it's way.

1) No need for greenboard on the opposite face of the shower walls. If you have a plumbing leak, you have bigger problems than the greenboard can handle. Have your plumber do a 24 hour pressure test (house pressure) before you give the drywaller permission to close up the walls. Keep the pressure on while the remaining work is done, just in case someone pokes a hole in your plumbing.

You might consider adding some unfaced insulation for sound control.

cx
04-11-2011, 02:05 PM
Welcome, Kim. :)
...the idea of cutting slits in the insulation, he didn't like the idea of messing with the fiberglass insulation at all... You're not gonna be doing any cutting of the insulation at all, Kim, only cutting slits in the paper facing on the batts. You'll barely even be aware of there being fiberglass in there if you do this correctly.

And what Bob said.

Note also that your batt insulation, as usual, is poorly installed and not sealing the bays all that well anyway. But you're not looking for accuracy here, only the defeating of the barrier so moisture vapor isn't trapped. Random vertical slits a foot or so long and spaced about the surface will serve fine. Be creative, make an attractive pattern to be enjoyed for two or three minutes before the wall board goes up, eh? :)

My opinion; worth price charged.

kl
04-11-2011, 02:59 PM
Hi,

You guys are great with your quick replies. Bob mentioned asking the plumber to do a 24 hour pressure test. I previously asked the plumber to check the pipes for leaks and he did something that took just a few minutes. We also have a pressure gauge attached to our water heater that was recently installed that shows the current pressure and registers the last spike, as we recently learned that our pressure was too high and was causing some other issues elsewhere in the house. I assume you are referring to a more involved test.

You mentioned keeping the pressure test going while work is done in case someone pokes a hole in the pipe. In regards to that, which worker might be more likely to poke a hole, the drywaller or installer? Does it make a difference whether the drywall goes up first in the bedroom/closet wall, before the tiler does the cement board? Or, the drywall after the cement board? Does the order matter in terms of potential issues? We currently have the drywaller scheduled to come a day before the tiler installs the cement board.

Thanks,
Kim

bbcamp
04-11-2011, 05:22 PM
In my line of work, we do pressure tests at 150% of design pressure for 30 minutes or however long it takes to visually inspect all the piping joints. That's not practical for a homeowner, so leaving the pipes pressurized at normal operating pressure for 24 hours gives plenty of time for leaks to show up. Again, you inspect all the joints visually. I like to take a clean tissue and wipe along the joints, then look for wetness on the tissue.

Use the system pressure gauge as a means of detecting a big leak in the system, but use your eyes and hands to find it.

With regards to which worker might poke a hole in your pipes, any that drive fasteners or drill holes into the studs are capable of causing a hard to find pinhole leak in the walls. Pipe/wire protectors can help. These are metal plates that are fastened over the stud where a pipe or wire is drilled through. They are strong enough to make driving a screw into the stud nearly impossible, so anyone who's half paying attention will stop and check before continuing.

kl
04-13-2011, 08:08 AM
Hi,

My installer is doing 2 coats of RedGuard. I'm not sure what application method he uses, but he does not measure thickness with any tools or pay particular attention to the square foot coverage instructions. When I ask him about measuring thickness, he just says 2 coats are enough and leaves it at that. We are installing 13 X 13 porcelain tiles and he is using Admix with the grout. So, do I need to worry any about thickness, or am I good with what he says? He seems experienced with tiling and has used RedGuard before.

Also, we are doing the tiling before the sheetrock on the bedroom and closet walls are being replaced. If we use the shower a few days before putting back up that sheetrock (on the other side of the framing), we will be able to see the backside of the cement board. Is looking at that back side or checking it for moisture, after a few showers, a good test of the waterproofing?

Thanks,
Kim

bbcamp
04-13-2011, 08:31 AM
If he was doing a pan with Redgard and not measuring the thickness of the application, I'd run him off. A tub surround is less critical, but the waterproofing is important enough to do a minimum of checking. The instructions offer two methods of applying the membrane, using a notched trowel and a roller. If using the correct notched trowel, I would have some assurance that the correct amount of material is making it to the wall, even though there would be no assurance that it was spread uniformly and completely. A roller may be more convenient, but the quality control is even less. Even with a thickness gage, your installer is the final quality check a roll-on membrane will have, so you will be relying on his skill and attention to detail no matter what.

The good news is that you should be able to see a pretty consistent color across the wall. If some places look thin, have him add more.

There is no test you could perform to verify adquacy of the installation. Time will tell.

cx
04-13-2011, 08:41 AM
Kim, your installer should be able to demonstrate to your satisfaction that he is applying the waterproofing product per the manufacturer's instructions. The only method I know of for doing that with a liquid-applied membrane is to use a wet film gauge. And he should have one in his truck.

It's quite common for folks to use products like that for years without ever having checked to see if they were complying with the manufacturer's recommendation. And it's not at all an intuitive thing on some of the materials. It can be rather difficult to get the proper coverage without checking your own work from time to time.

RedGard must end up with a dry film thickness of at least 30mils. That's a pretty thick membrane and that minimum thickness must be present over every square inch of the surface. It's not as easy to accomplish as one might think, since it requires twice that thickness when wet. Applying a consistent 30mil wet coat is not as easy as one might expect.

Which is why some of us are still pretty leery of using liquid applied products for shower pans.

My opinion; worth price charged.

kl
04-13-2011, 01:12 PM
Thanks everyone for the replies. With your help, I feel more comfortable with things. Having had mold remediation once already, I want to avoid it a 2nd time, if possible. I really appreciate the time you all spend answering everyone's questions.

Kim

kl
06-30-2011, 02:35 PM
Hi,

Our contractor completed our shower/tub surround tiling project about 2 months ago. Things went pretty well at the time of installation, except for some difficulty he had caulking the gap at the tub border, which was a little over a quarter inch on the long side. Small cracks developed in the first round of caulk and he had to come back out two more times within the first few days to add more caulk. He did not remove the initial caulk, as he said it was clean enough for the new to adhere. That seems to be holding up okay, so far. He said the gap was large because of the curve of the lip in the tub.

My question now is in regards to cracks that have developed between the tile and the door casing. On one side, the tile goes all the way up to the bathroom door. This casing is about five and a half to six inches outside the tub/shower, and it appears to be grouted between the tile and the door casing. I have done enough reading to know that this probably should have been caulked rather than grouted.

What would be the steps to correct this? This is not in the water exposure area specifically, but I suppose could get an occasional splash. I have included some close up pictures, and another photo that shows how the tile goes out on that wall, then it is indented a half inch, before this casing. We have left over matching sanded caulk. Can this be filled in this crack on top of the grout, or does grout need to be removed from that space? If any grout needs to be removed, do you have to remove all of the grout? There is also grout on the opposite wall going up to wood window casing, outside of the water area, but no crack has developed in that area yet.

I am also including a couple of general photos of the project.

Thanks,
Kim

cx
06-30-2011, 03:16 PM
Kim, there is a reason the tile industry standards call for a flexible sealant (caulk) between those dissimilar materials. Your photos are a perfect example of that reasoning.

YouYour installer needs to remove the grout from those lines and install the correct material there. Outside the wet areas, that sanded acrylic caulk you have will work fine. Don't feel sorry for him having to return still again, he should certainly have known better than do that.

My opinion; worth price charged.

kl
06-30-2011, 04:08 PM
CX,

A couple of questions:

1. You mention "Outside the wet areas, that sanded acrylic caulk you have will work fine." That sanded acrylic caulk is also what he used where the tile meets the tub. Are we okay with that product there, since that would be a wet area? I know it may not last as long as silicone. The caulk used is made by Color Fast for Interceramic Tile store.

2. Should I also have him replace the grout where the tile meets the window, even though it has not cracked yet after 2 months (like the door area) or leave that be. The window area is about one foot outside of the bathtub area, on the wall at the far end of the tub.

Thanks,
Kim