Redoing bath wall

[Denray]

Pulling out tile over greenboard. Will put Hardiebacker on. Is that unfaced insulation dark from moisture related issues? The wood seems to be fine. I see that there is paper faced insulation to the right, which is the garage side. Should all the insulation have a moisture barrier face on the shower side? I'm going to coat the Hardibacker with RedGuard, so it will be water proof. Wall is 22 yrs old. My house.

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[kurt]

It's "mould". Run for your life.

[hausdok]

Hee, Hee,

Looks like dust that got sucked into the wall from places unknown via air infiltration.

ONE TEAM - ONE FIGHT!!!

Mike

[Les]

Now Kurt, you know it is not mould until I go test it. I'm running a special this week and will gladly fly to Ca, test and report results for a nominal fee.

I don't think it is moisture related and if it was, your new work will prevent it for happening again. I recently had very similiar issue with bath wall and just changed a section of fiberglass insulation 'cause I didn't know whay it was darker. Cheap fix. no vapor barrier on shower side between backer and insulation.

Why did you choose Red Guard? The tile setter for my bathroom would not place a single tile until I agreed to Red Guard. He didn't charge me for any labor to apply it or make any profit from the product; just insisted we use it.

[Denray]

There are 3 or 4 waterproof coatings out there. That's just the one available close by.

If I hadn't used a bunch of small tiles that are hard to seal at the bottom next to the tub and knew that backer rod was at the time I did this work it would still be holding up fine.

It was hard to take the first blows at it with the hammer. But, soon I just treated it like it was Obama's windshield.[:-monkeyd

[kurt]

Waterproofing coatings on backer board have been around for a long time, but they've only recently (last couple of years) been getting attention from the mass of tile installers.

I don't think they're necessary in the average shower enclosure if there's adequate room ventilation and the tile was installed competently.

They are absolutely necessary in a steam shower enclosure, especially when the shower is on an exterior wall.

I'm making a small plea for keeping even the slightest hint of politically minded commentary out of TIJ. Everyone gets to believe what they believe, and to tell everyone about it anywhere but in here.

[kurt]

Hee, Hee,

Looks like dust that got sucked into the wall from places unknown via air infiltration.

ONE TEAM - ONE FIGHT!!!

Mike

I see this condition all the time; I always thought it was from minor condensation issues, and it was, in fact, a little mildew.

[allseason]

Could be dust sucked in by the exhaust fan, if there is one.

[Denray]

So one tile guy says butt the C board up to the top of the tub lip with a little clearance for expansion and fill gap with silicone. The other guy says fur out the studs far enough so the C board laps over the lip with a little gap to be filled. If I do it the second way then the bull nose on the edge will be higher than the surrounding drywall. Seems like with the RedGuard there would be no worry about the first method and the tile would lye even with the drywall.

Watcha think? And thanks for all the comments!

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[kurt]

I shim out so the backer is at the lip, the tile overhangs the lip; I hold the backer up off the tub about 1/8".

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[Denray]

Uda man Kurt!! No bother with RedGuard sounds good to my smart contractor friend, too.

Plus that no grout at the bottom deal. I replaced the big hunk of silicone sealer at the bottom of the tile because I thought I could keep it cleaner. The grout broke free of the tub like a weep screed and started sucking up water there via capillary action. Long story short, now I'm busting it all out.

[Tom Raymond]

Denny, how cold does it get in Eureka? I ask because in my climate we should be covering the studs under the tub, we never do though.

The discoloration on the insulation is dust and debris sucked out of the crawl into the cavity under the tub, into the wall and eventually out whatever your attic vents are. Just like your furnace, this air flow will be much more efficient if you replace that dirty batt.

I'd do a little airsealing while that's open.

[Denray]

If so, then strange how the insulation above and to the left is not dirty? Could have been just a dirty hunk of insulation the builders put in. I only got involved after the greenboard was up.

My previous greenboard only had water damage at its bottom lip, which was not sealed to the tub. If I choose to not do the RedGuard thing do I need a vapor/moisture barrier behind the C-board?

Seems like the RedGuard is a fairly easy thing to apply.

Thanks again all for the responses!

Oh yeah, there was a bit of a hump in my tile before just right of the shower head wall. After doing all this HI stuff I figured it had to be some kind of swelling. It turned out to be a nail guard for a drain. My tile job was great except for that bottom edge thing. "Nice boat except for that one hole".

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[kurt]

Remove green board from your vocabulary. I grudgingly concede it can work, sort of, but why? Durock.