I am under the impression that water can deteriorate gypcrete used in radiant floor applications. Is this the wrong impression?
Specifically, I have been told it is risky to pour gypcrete where leaks could occur (bathroom, kitchen, etc). Should a leak occur the water could ruin the gypcrete.
Also, is the gypcrete an acceptable underlayment for tile work (natural stone) or should cement board be installed also?
Thanks, Jeremy
Replies
Good god I hope not!!! I just did the 1st floor complete with the powder room, laundry and both 2nd floor baths. The house is in Northern Maine and the floors get wet sometimes with melting snow. Wood floors are in the DR and LR. Bedrooms are baseboard.
Tile is going on 75% of the 1st and both baths on the 2nd. The installer did leave 2 gallons of additive for the thin set. Said to call if I run out and he'd drop off more.
It seems standard in my area Sierra Nevadas for the gyp to go everywhere. Hence my confusion with the thought of H2O ruining gyp.
Water should not ruin it, although if you have a constant sort of leak, all bets are off...you'd probably want it fixed just on principle.
>Also, is the gypcrete an acceptable underlayment for tile work (natural stone) or should cement board be installed also?
Don't use cement board. Do look into anti-fracture membranes. Without them, the risk you run is that the tile will be bonded to the gyp, and any cracks that develop in the gyp (and there will be some) will telegraph through to the tile. The AFM prevents that. That's the theory...I've used it and have no cracked tiles...don't know what would've happened without it.
My experience with gypcrete is that it does soften when it gets wet. This is the older gypcrete that was poured in the late 1980's.
The older gypcrete also had compressive strengths of less than 2000 psi and stone tile manufacturers do not recommend using it as a substrate. Newer formulations of gypcrete give strengths well over 2000 psi and might be okay for tile.
But make sure you have a proper floor system before laying tile. In condominiums (where else do they use gypcrete?) a typical floor system is 3/4 inch gypcrete on 1/2 (maybe 5/8) inch osb, possibly plywood. No good for tile.
I took a 2 day course for certification in self-leveling cement at Ardex. During the course they compaired their propuct with gypcrete. One of the downsides of gypcrete, according to Ardex, is that gypcrete has a starch in it and when it gets wet, it is a perfect breeding environment for mold. The starch is food for mold.
SLC has no starch. This is why gypcrete is no longer used in hospital projects.
I seem to also recall that gypcrete is not recommended as a substrate for carpeting due to the ease of contact with moisture and the mold issue.
The Mapai seminar made the same claim regarding their SLC.
F
There he goes—one of God's own prototypes—a high powered mutant of some kind never even considered for mass production. Too weird to live and too rare to die.
—Hunter S. Thompson
from Fear And Loathing In Las Vegas
I used some kind of self-leveling floor mix on about 1500 sq ft[kit bath laundry and hall] had several diff mixes to choose from. all the way from dries-up and blows away in a good breeze to stuff that would make good armor for a tank. this went on a lowered floor system with 2 inches of blue-board,. poured 2 inches thick,electric heating grid and tile,sawn-brick, stone etc finishes. 5years and still going strong. the key here being the diff mixes I had to choose from.