My problem is this We installed a tile floor over floor heat. It is new construction, an addition 12 x 16 2x 10 x 12 16 inches on centre, 3/4 t &g osb with 3/8 plywood screwed down over that. Floor heT EKECTRIC CABLE ,FLOOR LEVELOR AND THEN TILE ON THINSET.
Problem is it cracked straight across length of joists every 4 feet thru the centre of the tiles , there is no grout cracking whatsoever. What would cause this. Can the underlay expand that much if it was too tight in this small a space, or is the floor heat the culprit HELP
Replies
>>Floor heT EKECTRIC CABLE ,FLOOR LEVELOR AND THEN TILE ON THINSET.<< Are you saying that the radiant electric floor heat cables were stapled down on top of the plywood, a leveling compound was spread over that, and then the tile was installed with thinset? Got a web link to the electric radiant floor heat system that was installed?
>> Problem is it cracked straight across length of joists every 4 feet thru the centre of the tiles , there is no grout cracking whatsoever. << That sentence is a little confusing...
Anyway... so, it is cracking 4' on center... are these 4' lines where the joints of the plywood is? Where the joints of the OSB subfloor is? Are the joints of the plywood aligned with the joints in the OSB subfloor? Is the cracking following where the heat cables are?
Matt, it seems to be at every joint in the plywood. it is over a crawl space which had some moisture in the floor. The new addition was framed in severe weather conditions. my theory is there was too much moisture in the floor when it went down and too much moisture in the crawl space under and the plywood expanded and split the tiles above the plywood joints. do you agree?
If the cracks are every 4 feet, that seems to correspond with joints in one of the plywood layers.
"Put your creed in your deed." Emerson
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I think your pwood is expanding and causing the cracks.
The proper way to install this would be to space the pwood 1/8" between sheets and then caulk the seams before pouring the floor leveler. Also, I don't ever lay any pwood thinner than 5/8" under any kind of tile floor. Too many problems.
Seems like if anything, after it was dried in it started drying out... so, no, I don't agree.
Please answer the previous questions. What part of the under lying floor system are the cracks following? You said the cracks were 4' on center across the length of the joists (or similar). Please explain further or edit you initial post to make it clearer. Did you lay the 8' dimension of the subfloor parallel to particular to the joists? Sounds like you ran the 8' dimension of the subfloor parallel to the length of the joists...
Matt I had a sub install the underlay and do not remember . They could have run it paralell with the joists cause the 3/4 osb would have ran oppisite to the joists, so i would say yes the 8 foot length of the underlay would be running paralell to the joists and that is where the cracks follow. Full lenghth wall to wall the length of the underlay,through the centre of the tile,actually splitting the tile in two with a hairline crack but not much separation. the crack does not follow a grout joint. If the tile was pocelin I wonder if it would have cracked
Brent
could be floor leveler too thin ...
and definitely could be no isolation membrane.
could be a combo ... but a good isolation membrane could have helped hide the cracks in the too thin leveler.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa