Tile Adhesive Recommendations Needed

[jdp]

Thought I was doing myself a favor and some good buying OmniGrip yesterday - now after everything I read, it wasn't a good move. So, before I make a mistake, I want some clear advice from the pros.

I am finishing a section of my basement. A part of it I'm am going to have tiled. It's about 80 square feet and part of that is in a closet.

The basement is very dry; after 16 years, we have only seen dampness on the side of crack after the Mother's Day flooding up here in New Hampshire. We are on very high ground.

I've adhered and screwed backboard onto the cement, in order bring up the height to match the carpeting and to even the area. I will be using thinset to seal the joints.

The tiles are 13X13 and the trowel that I have gotten is 1/4 X 1/4 X 1/4.

What should I be using for setting the tiles? Brand?

Any and all other advice will be gladly accepted.

[Floorguy]

I will say, OmniGrip from Custom, is the best Mastic produced. Thier advertising a couple of years ago, had a bucket of OmniGrip(I thought it was named OmniBond) Glued to a shower wall, saying it was great for shower wall application.

I would not use it on a floor though. Get a bag of Flexbond mortar!!!

[jdp]

Thanks Floorguy,

The problem I understand with the OmniGrip is that it take foreer to set. People have actually taken up the tiles and removed it and started again with something else.

Thanks for not getting off on my use of backerboard on cement.

I'll look into the the Flexbond.

Love your salutation too.

[hookknife]

You might want to use a larger notch trowel also, or back butter your tile, either way check to make sure you are getting the proper transfer of mortar from substarte to tile.

[jdp]

Been considering the larger trowel, too.

Been reading up on Flexbond and Versabond popped up as being, maybe not as top-notch, but close. But, the big point was that it is easier to use for a novice.

Any comments?

[Bud Cline]

I've adhered and screwed backboard onto the cement, in order bring up the height to match the carpeting and to even the area. I will be using thinset to seal the joints.

Did you use thinset UNDER the backerboard?

[jdp]

No, I used a construction adhesive for porpous surfaces. The area is very small 5 X 8, and a closet. The backboard is surrounding on three sides by walls. I really don't see it shifting.

Furthermore, I understand that a concern of backerboard is sags, but it can't on a concrete surface.

[Bud Cline]

Fasteners when installed in cement backerboard create voids under the board. The thinset under the cement board is not used to bond the board to the substrate but rather to fill the voids created when the fasteners are drawn into the substrate. ALL cement board manufacturers want you to use thinset under their boards for this reason. The use of construction adhesive (if not spread for 100% coverage) will in time cure very hard and enhance the probability that any existing voids will become springy when pressure is applied. It is also further recommended that cement backerboard NOT be used for application over concrete.

Versabond is an excellent thinset for tile installation over cement backerboard but likely won't absorb any flexing that may develop. Flexbond may be the better choice in this case. MegaFlex would be better.

Organic adhesives even though the instructions say they can be used for floor installations - should not be used for floor installations because the adhesive dries very very very slowly (if ever). Movement in floor tiles can exist as a result.

Taping cement board seams with thinset is best accomplished while installing the tile so as not to create seam buildup that would cause tiles to teeter and create lippage issues between tiles. The seam tape required is an alkali-resistant seam tape sold especially for the purpose. Drywall seam tape does not qualify.

The back of the tile and condition of the substrate determines which trowel should be used. Typically a 1/4" X 1/4" X 3/8" trowel does the job with 12" tiles. A few installed tiles should be periodically removed to verify thinset coverage, 100% is the target coverage but 85% is acceptable. Should the coverage not be acceptable the individual tiles can be back-buttered using the flat side of the trowel after combing thinset on the substrate. Combed thinset should be applied in straight lines with no curves or swirls.

[jdp]

Bud,

Thank you for the first explanation as to why mortar should be used, but when questioning how to raise the surface to match carpet height, I've got nothing. When I brought up Backerboard, I got don't do it on cement - but still no explanation as to why it can' be used on cement. Enough of the backerboard discussion for me for one day. I'm going with it and feel pretty confident I will not run into problems.

But, a real thank you for all the advice on the actual application of the tile and the mortar to be used; the real question asked. You have been very informative and advice will be acted upon.

Will take the after precautions of lifting tile into consideration tho. We have all the bathrooms and nearly the entire first floor tiled and have done nothing to check them. It has been nearly 17 years since they were installing. A few tiles were cracked even when we moved in (we should have reacted then.) We have not seen any other tile concerns sinces we had the house built (except for the occasional dropped glass that dented the cheap tile we choose for the kitchen area; loved to pull it all up - another project, someday when it make sense in this housing market.)

Again, thank you and others on this board (and other boards) regarding the application of my tile.

[stullis]

Might as well use the OmniGrip for the floor too.
It will dry fine on the backerboard.

Flex in the name of thinsets has typically NOTHING to do with an ability to absorb or handle any movement.

This is a prime example of people not having an understanding of what they are reading on the internet.

[Bud Cline]

Flex in the name of thinsets has typically NOTHING to do with an ability to absorb or handle any movement.

Not at all true these days according to manufacturers.

Some of "today's modern thinsets have the ability to allow lateral movement between the substrate and the tile" says some of the manufacturers. These thinsets are marketed boasting of these abilities. This is why I mentioned MegaFlex above.

[Peter Kodner]

Good article on this in this months FCI.

[TFP Admin]

Peter Kodner said Good article on this in this months FCI.

Unfortunately, jdp and other DIYers don't have access to that magazine. Could you provide some pertinent excerpts?

Thanks,

T

[Peter Kodner]

Oops I'll reread, distill and write up a comment. I actually was more referring to stullis' and Bud's comments...

[stullis]

Manufacturers adopted that understanding as a marketing ploy because that is what installers thought is what was meant originally.

Now they have actually engineered some of those properties into some thinsets with mixed results but the "marketing machine" is hard at work.

Personally MegaFlex and SuperFlex I would not recommend to use for their "antifracture properties" in this case. In any case, no thinset will help with any kind of vertical movement which is what this guy will have after using construciton adhesive under his cement board.

I do agree with Bud on using a better thinset on the backerboards but not for the same reasons and many consider the use of the high $ thinsets a waste of money.