Porcelain tile on concrete question

[Bob2112]

Hi all -

I'm leaning towards putting porcelain tile on my workshop floor. It's about 1200 sq ft (30x40). I've done numerous residential tile projects have used either Ditra on wood subfloors or kerdi on concrete slab bathroom applications for waterproofing.

My question for the garage project is this: do I need to use any type of waterproofing or isolation membrane on my slab?

The slab is between 6 and 9" thick and is about 2 years old. No vapor barrier was placed under the slab. It is on top side of the elevation rise on my property, so water drains away well.

My question arises from my understanding that moisture can weaken the tile to concrete bond. So I'm wondering if it would be good to stop moisture from coming up through the concrete by placing a membrane on top. But, that makes me wonder if that would be a problem because then moisture under the slab can't 'dry out'. But maybe that isn't an issue given the lack of drainage issues.
Located in the reasonable rainy climate of middle Tennessee.

Any thoughts are appreciated, and if any other facts are needed, just let me know. Thanks!

 

[KDubU]

I tiled out garage three years ago with porcelain tile and did not put a membrane underneath. It has held up well, looks great and handles the two cars no problems. I went with 2x2 tiles, PEi 5 and it took a weekend to do a 24x24 garage.

Now we don't have any moisture issues, the slab would "sweat" a little if the doors were left open and humidity was really high. If you're concerned, go with a membrane as it sounds like your garage is high and dry.

 

[mike93lx]

Membranes like Ditra are not only for waterproofing, they decouple the tile from the floor, which can help prevent cracking. that said, on a stable, concrete floor, it might not matter. my understanding is that they have more of a use on a floor that might have some flex, like a wood framed house.

 

[Lelandwelds]

I have been in old factories and old butchers with hundred year old brick and tile. I am sure they didn't have plastic decoupling membrane or under slab vapor barriers.

 

[gerryw]

I tiled out garage three years ago with porcelain tile and did not put a membrane underneath. It has held up well, looks great and handles the two cars no problems. I went with 2x2 tiles, PEi 5 and it took a weekend to do a 24x24 garage.
Now we don't have any moisture issues, the slab would "sweat" a little if the doors were left open and humidity was really high. If you're concerned, go with a membrane as it sounds like your garage is high and dry.

Exactly same as my situation, no issues at all, i used a thinset with latex additive for freeze/thaw.
I did use redgard roll on crack membrane on any cracks. 13”x13” tiles
Down 3 yrs
Gerry

 

[Dakota00]

As long as the slab is solid, with no visible cracks and/or shifting has occurred. There's nothing to worry about. No need to use a decoupling membrane or waterproofing membrane either. You're good to go!

 

[Bob2112]

Thanks for the responses guys! I'll probably throw some redguard on any existing cracks, but other than that I'll skip the membrane.

 

[James-W]

Be sure to post some pictures of the progress.