Moisture Resistant Dry Wall and Mastic for tub shower surrounds

I thought I have seen everything in Vancouver Condo work but this is a first. The tub shower we demo'd yesterday was built as piss poor as they come. For one they used moisture resistant drywall and mastic to set the tile. There was no waterproofing on the walls at all and not even the ledge had any extra care. For the life of me I can not understand how it held up for 12 years like it did.

Once I chipped out a small spot I noticed the tell tale signs of Mastic and Green DryWall.

The Green Drywall was made in Edmonton a tag said somewhere but I could not find out any brand name at all. It's brown in colour - I've not seen this before but I don't work with drywall when building showers and never bought into the "Moisture Resistant" concept.

Look at the colour of this stuff.

They kept the board off the tub lip about an 1/8" and that's it.

One clip and the rest was wafer head screws holding the steel tub still.

What blows me away the most is the tubs ledge was in perfect shape. WTF!!!

Mind boggling.

This tub does not get used as a shower since we finished a steamer in another bathroom a couple years back but I think the real savour for this project is once again the condo's design. In many condo's there is a strong draft of air current in the bulk heads and I suspect without this a shower like this would have long since failed.

Back when you where allowed to build this way it was required to flat trowel the mastic first and then let it dry before installing tiles to the wall. This step was not done and goes to show anything is possible.

Is all mositure resistant drywall brown in colour like this? I've not seen it before???

JW

I have a customer right now who had an HVAC drain leak in the attic down the wall of the shower with travertine stuck onto drywall........now the back of the wall has mold growing all over it and 1/8" of it is goo......yes it is gooey. Very weird. Now the whole shower must be torn out. If they had used cement board it could stay. Just to re-do the shower is going to cost 4 to 5 thousand and thats minimum.

Speak of the devil.

I know it isn't the accepted backing now, but wasn't greenboard the standard backing for tile for many years? Just asking.

Gary Swart said:

I know it isn't the accepted backing now, but wasn't greenboard the standard backing for tile for many years? Just asking.

Click to expand...

It was and we have ripped out so many. Green Drywall was being used with Mastic for years and years. This Green Drywall is brown under the paper. I have never seen this ever in a remodel and I have never seen it sold here in B.C.

The fact that it held up so long I think is more to do with the airflow behind the stud walls than the drywall being "Moisture Resistant".