Need advice on floor prep for porcelain tile

[Wakesurfer]

I am getting closer to doing the floors of my garage project and have been reading a lot of threads about epoxy vs tile. I'm leaning towards 12X12" porcelain tile. If I go that route, I need to solve a drainage/slope issue. My garage floor is 45' X 30' and has two floor drains spaced evenly on the centerline. The floor was supposed to slope towards the drains so one would not have to squeegee any water to the drains. Unfortunately, the concrete was not pitched aggressively enough, so each drain has a low spot near (2-3') the drain where water pools. It is not off by much (maybe 1/4"), but it is definitely lower than the drain. Unfortunately, the sub who did the work died. We (the GC and I) are trying to figure out the best solution. Any ideas? If we grind down the concrete to create a better slope to the drains, I am wondering how far the area would have to be feathered so tile could be set without future cracking. Has anyone else dealt with this issue, and if so, what did you do?

Thanks

 

[slickgt1]

Look at it this way. Tile will follow your floor pitch, presuming you do it that way. That low spot, it might actually be straight when you tile it, as in resume normal pitch. You can also adjust the thickness of the thinset a little to help you fix minor issues. If it is a huge issue, you can do a dry-pack-mud job. I did this in my garage, see link in my sig. Renovation thread. But I did that to correct about 3" - 4" of really messed up pitch all over the perimeter.

Get some scrap tiles and lay them out by the drain. Take a straight edge and a level and see if the tile fixes the low spot without further messing around, while still maintaining drain pitch.

 

[Zeke]

Seems to me the tile thickness itself begins to solve the problem. Once the floor is installed the drain should be below the floor level. All you have to do is span that low spot. Lots of products and methods to do that.

 

[kj_mustang]

Fill the low spots with a self leveling underlayment first before going over with thinset and tile. Something like this

 

[Wakesurfer]

Thanks for the advice! I guess it never occurred to me that just leveling the low spots might solve the problem! If, after filling in the low spots, the immediate area around the drains still needs to be lowered a bit, how would you recommend? If I have to lower the high spots 1/2" to encourage better drainage, how far would that need to be blended to avoid lots of tile issues?

 

[slickgt1]

But the tile would automatically be above the drain. You would actually need to raise your drain cover a bit.

 

[509SC]

You'll probably end up raising the floor height 5/8-3/4" depending on tile thickness. If the floor has pitch to the drain (except for the low spot), simply fill the low area with thinset and strike it off. Then install your tile. The drain will have to be shimmed up if you want it somewhat flush to the tile. I would set it about 1/8" below the tile. In the end, you'll probably still want to use a squeegee to direct the water and get the floor to dry quicker. Another thing to realize, is that you'll probably lose some of the pitch around the drain area unless you cut those tiles diagonal or into smaller squares. It's pretty hard to set tile with minimal lippage on sloped surfaces, tile does not bend!