Tiling over gypcrete ** Is it OK?
I’m confused over the discussions regarding tiling directly on gypcrete surface. I have a 3/4″ wood substrade. I had 1 1/2″ gypcrete poured over my hydronic radiant heating tubes. I plan to wait for one month before putting in the flooring.
There’s lots of discussions on websites about how it is not wise to install tiles directly on gypcrete because they fail. Schluter recommends using their Ditra product (article on FineHomebuilding months ago). Maxxon which makes the gypcrete product does not seem to care as their website shows thinset directly connecting tile and their gypcrete product.
Are problems due to the lack of curing time, or is it because thermal expansion rates between gypcrete and tiles (natural or ceramic) are different and thus causes separation and cracks.
Anyone with first hand experience on how to make tiling on gypcrete durable is much appreciated.
Replies
Seems that if the expansion rates of tile and gypcrete are different, an isolation membrane would be the way to go and would prevent problems. But I am no expert on tile, especially no experience with tile over gypcrete! You've probably already looked on the johnbridge web site?
Danno's right. Differential expansion requires the use of an anti-fracture membrane, or isolation membrane, so that inevitable cracks in the gypcrete won't telegraph through the tile, given that the thinset bond between tile and gypcrete would be strong enough that the tile would give before the bond did.
Edit: That comes from firsthand experience. And I hate working with the membrane, because it's unforgivingly sticky and the installation has to be just right, but it is the right product for the job.
Edited 8/19/2007 10:30 am ET by CloudHidden
This anti-fracture material - is that an actual membrane like Ditra, or is it a paste one could trowel on? I've seen the paste advertised also, but not sure what you have experienced that really worked for you.
What I used was supplied by the gypcrete installer. It was like this: http://www.nacproducts.com/ECB.htm , though there are many brands. Self-stick rather than trowel on. I'll defer on other products I have not personally worked with.
any and all.
self stick ... ditra-like mats ... roll on liquid stuff ... thin mats U embed into rolled on stuff ...
less thin mats U lay into troweled thinset ... like ditra ... cept thinner.
then there's the thicker ones ...
etc.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa