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Frizzle 07-27-2013 10:28 AM

Small Master Bath Remodel
5 Attachment(s)
Hi everybody,

I am having my bathroom completely remodeled from the studs, and the contractor just put up the cement board, sheetrock, and spackled.

After he left, I saw that in some areas, the Durock is crumbled in the corner and in a couple other areas. He also left a space by the front side of the tub where the wood beam is exposed. Is this acceptable?

I've also learned from doing a little quick research just now, that all the seams should be taped, and a water barrier (like Redgard) should be applied on top of the Durock. I'll make sure to question the contractor about that.

Please take a look at the pics, and tell me if you think everything looks ok so far.


Frizzle 07-27-2013 10:30 AM

2 Attachment(s)
2 more pics

Tool Guy - Kg 07-27-2013 11:19 AM

Hi Ron,

When the seams and corners are taped with alkali-resistant mesh tape and mudded with thinset, those relatively small areas will be repaired just fine.

The wall area down at shin level......adjacent to the tub's apron on either side is a highly prone area to moisture damage. It's a common area to rot out if it's just drywall...even if tile is covering it. I'd want the cement board substrate to extend out at least 2" out from the face of the tub apron.

And you'll want either a moisture retarder behind the cement board (overlapped onto the tub's tile flange) or a surface waterproofing on the front of the cement board (not both). You've already mentioned and we can see from the picture a lack of a moisture retarder behind, so a surface waterproofer is a good method to proceed from here. This type of paint-on waterproofing is done after the seams are taped, mudded (with thinset), and dried properly. Do realize 2 coats of the appropriate thickness are required by the manufacturer to make it waterproof to their intended level of performance.

Finally, I can't tell from the first picture, but your temporary plaster guard (also serves as a depth guide) from the mixing valve seems like it may be out a little too far. Can you show us a closer picture? A view from the side just like the first pic in your post would be great.


Frizzle 07-27-2013 11:28 AM

1 Attachment(s)
Hi Tool Guy, thanks for your response.

That plastic cover was just about falling off, so I took it off and took the pic:

Frizzle 07-27-2013 11:29 AM

One other thing I just noticed. When I pushed on the Durock a little bit right around the valve area, it is not completely solid feeling. There is a litte movement. Is that ok?


Tool Guy - Kg 07-27-2013 11:42 AM

You'll feel a little deflection around the mixing valve hole. So long as it's fastened tight to the studs and they aren't spaced further than 16" part, it is fine.

Can you snap the plaster guard back in position and hold a tile up against the wall immediately adjacent to the plaster guard?


Frizzle 07-27-2013 11:54 AM

2 Attachment(s)
sure thing:

Tool Guy - Kg 07-27-2013 12:40 PM

Thanks, Ron. :yo: The thickness of that plaster guard represents the "min/max" zone of the finished wall plane. With your tile face falling comfortably within the "min/max" zone (even with the expected added mortar thickness during install), you're good to go. :)

Frizzle 07-27-2013 12:50 PM

Thanks Tool Guy!

It's the first time I've been through this, and will be the last (at least in this condo), so I want to make sure everything is done right :tup2:

Tool Guy - Kg 07-27-2013 01:11 PM

Condo, eh? Are you in a high-rise? Are you tiling the floor, as well? If so, there is very often a "condo enforced requirement" to use some type of sound dampening membrane under your hard tile floor so your downstairs' neighbors don't hear you stompin' around. Do you know if your condo has this requirement? While all the condos I've worked in require this in some capacity, sometimes they are subdued if the tile is limited to just the bathroom, kitchen, & possibly foyer. You'll have to check, as this is up to each condo association board to make up their own rules.


Frizzle 07-27-2013 02:28 PM

I have a 1st floor unit and a finished basement, so nobody below me.

I wish there was nobody above me either :D

They should have a rule that the people upstairs have to have carpeting.

Ken 07-27-2013 04:26 PM


With regards to your concerns about the Durock being some what damaged, as long as your tile contractor properly tapes the seams and other areas that have been damaged, the installation will be fine. The other areas that I speak of are any broken or damaged areas that are not near a seam.. so he should apply some mesh tape over that portion and pack it with thinset. I've personally broken 1000s of sheets of Cement Backer Units in my career, no problems as of yet.. so no worries. ;)

Frizzle 07-28-2013 07:44 PM

Thanks Ken :D

My contractor texted me and said he would be coming over Tuesday morning to do the tiling and have me show them how I want it installed.

I responded:

"Are you going to tape the seams of the cement board with mesh tape, and paint on waterproofing stuff (like Redgard) first?"

His response:

"Yes we tape the seams when ready to install the tile. The waterproofing you are mentioning is not needed. You will have a leakproof shower without it. If you insist on having it done, this will have an additional cost."

I texted back that I want it done and asked what the additional cost is.
Still waiting to hear back. A gallon of that stuff costs $50. Anyone want to take a guess what his 'charge' will be? :D

I guess this is strike 1 against this guy. Now I'm getting nervous about his tile guy. He better do a good job.

As far as taping the seams goes, would he be able to do that and then install the tile right away? Or would that have to dry first for a certain amount of time?

Tool Guy - Kg 07-28-2013 09:27 PM

The thinset would have to dry overnight before applying the RedGard.

Once the thinset is dry, 2 coats can typically be applied on the same day. The first coat will probably be dry enough for a second coat within an hour or so. And the second coat, while taking longer to dry will be ready within probably a couple of hours. The time is really dependent on the temperature and humidity, though. The stuff goes on pink and turns dark red when dry. One of the biggest mistakes folks make is not applying it thick enough. Each of the two wet coats should be 30-35 mils in thickness. This is checked with a wet film gauge. The stuff dries and shrinks to half of its wet thickness. So, the final dry thickness should be 30-35 mils thick. Here's Custom's instructions for RedGard.

When the second coat is dark red, it's ready to tile.


dhowardpeters 07-28-2013 09:33 PM


Originally Posted by Bubba
paint-on waterproofing is done after the seams are taped, mudded (with thinset), and dried properly. Do realize 2 coats of the appropriate thickness are required by the manufacturer to make it waterproof to their intended level of performance.

Hey, Ron.:wave: If your contractor had put poly behind the cbu (overlapping the tub flange), then he could have taped the seams while installing the tile, but, since he didn't, he will have to waterproof the surface of the cbu. You have chosen a liquid-applied product for this. Therefore, he will have to prepare the seams first, like Bubba described.

*I hope a pro will further address the front sides of Ron's tub (tub legs) where there is no cbu. I don't think that important issue has been resolved. I wouldn't know what specific instructions to give the contractor to resolve it, short of explaining the problem and telling him to fix it.:rolleyes:

Why do so many contractors think cbus alone provide a leak-proof shower? I've read many threads where the homeowner was told this.:mad:

From listening to the pros here, my understanding is that while cbus are immune themselves to damage from water, they can allow water to pass through to your structure. Same with thinset and grout. Therefore, cbus, thinset and grout are not waterproof, and an additional water capturing/routing material is absolutely required, i.e. poly behind OR a surface-applied liquid or fabric membrane.

Good Luck, Ron. I'm glad you're here:)

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