cement underlayment problem

Ok so heres the big problem.
I have a 5/8" OSB subfloor which I forgot to prime and the electrician laid my in floor heating for my kitchen/entry way in total the in floor heat alone was (1400.00), and I poured the cement underlayment (self leveling stuff made by stone mason) and I turned the infloor head on very low like 8 celcius. About two weeks later my concrete underlayment started to crack and stuff (its about 1/4" thick) and the infloor heat still works but I dont want to lay tiles if I dont have a good solid base. But I also dont want to have to rip up all the cement underlayment and lose my (1400.00) infloor heat? I was thinking I could prime the concrete underlayment and add another 1/4" of it ontop of the primed stuff and just have a really big transition to my laminate? Or is there any other ideas?

You have several problems there. For starters, slc shouldn't be used over osb. There are a few slc's out there that say they can be used over osb, not sure which one you used. All slc's require a primer and lath over wood. I know you didnt use the primer, but not sure if you used lath either. Most slc's need to be poured a minimum of 1/2" thick over wood, but you indicate that yours is only 1/4" thick. Basically, nothing has been done right and this will never last.

You need to bust up what you did and start over.

Yep, sounds like a tearout and redo. Always do plenty of research before you decide to do anything you have never done before. Even better to just hire a professional.

So there is no way of salvaging my in floor heat thats mostly what I want to save

What SLC says it has to be a minimum of 1/2" thick? All of the SLC's I use says it can be poured and spread to a feather finish. Unfortunately you'll have to redo it all if you want it done right. Since the SLC didn't bond to the floor there's a chance that you can save the floor heat if you're careful and take your time.

Hi,

I agree with Stan. You can save the floor heat if careful about the removal of the self leveling compound.
My recommendation is to contact the Tile Council of North America, and ask them the best way to go.
You can also contact Schluter at their website, to see if maybe you can use their Ditra uncoupling membrane over what you now have existing, but I do believe they wil ltell you to remove the self leveler from the floor.
An uncoupling membrane is a material that although adhered with an unmodified thinset, it may rlease from the floor, but the tile will stay in tact, and not crack.
The only concern I ave with using it is that the self leveling material is cracking, and may give you a crackling sound over time.
Schluter may tell you that if the SLC is removed you can then put the Ditra over the top of the floor heat and OSB.
Hope this helps,

Linda
Aguiar Floorcovering in Florida

I am an installer, and have been to many seminars for all areas of this industry.

Stan

What SLC says it has to be a minimum of 1/2" thick? All of the SLC's I use says it can be poured and spread to a feather finish.

You are aware that this is over osb, not concrete. Tec's EZ Level is the slc I generally use.

Tec's instructions say the following. As far as I'm aware, all slc's instructions say something similar.

Surfaces must be primed with TEC Primer and Patch Additive (TA-861). Allow primer to dry to a clear film before installation of EZ Level. After priming, staple 1⁄4" (6 mm) galvanized diamond metal lath to the floor overlapping at seams. Install EZ Level at least 3⁄8" (9. 5 mm) deep for joists 16" O. C. (40 cm) or less and at least 1⁄2" (12 mm) deep for joists greater than 16" up to 20" (40 to 50 cm). Maximum EZ Level thickness is 11⁄2" (37 mm).

Jesus Christ! It's no wonder the tile installation industry is in such sad shape and jobs are failing daily.

There is NO WAY you want to use metal lath with an electric floor heat system. NO WAY!

I have never seen an SLC that can't be used over OSB. All of my heat systems are installed on OSB. None of them have any lath WHAT-SO-EVER!

All SLC's can be feather-finished, there is no 1/2" minimum I have ever seen - THAT'S REDICULOUS!

The deletion of the primer is a mistake but the primer DOES NOT prevent the SLC from cracking. It prevents it from curling and the moisture from being absorbed too quickly into the substrate. OSB is treated to prevent moisture migration from the weather while under construction so that base is covered. Cracking and crazing is normal.

So - - -

I would say your problem IS NOT serious. Get the tile down soon and that will fix all your problems. You have no worries with what you have done so far. To add another layer will not solve any problem. If you just want to spend money, send it to me.

Putz email me: budcline@inebraska.com

[Edited by Bud Cline Tile on Mon, Nov 23, 2009 at 6:40 pm CST]

Ok well I think I will make sure the floor is completely level by using slc in the low spots and I will lay the tile and hope for the best. Thanks

I agree with Bud Cline Tile. I don't think your problem is serious.

Putz, just for your information, SLC is not intended to level low spots without a neat coat applied on top for a smooth & level substrate for tile, I have pre-leveled low spots with SLC and then applied a neat coat @ 1/4" depth.

If you lay tile on a substrate with lows & highs, you'd need to be a Very GOOD PRO to get the tile level.

Tile contractors, just for your information, Ardex liquid backer board, Saves installation time, saves labor, saves money, install tile in as little as 6 hours, installs over most wood sub floors, needs no wire mesh, completely compatible with radiant heat systems, mixes with water only.

Tile contractors and installers, You can find Ardex liquid backer-board information on our website that introduces this self leveling floor compound.