Wood left in slab. [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Tile Rookie
06-13-2001, 10:37 AM
Hey there love the site I have used it alot. Thought I would get involved. My question is what to do with a left over door sill that was left in place when a remodel was completed. It's a 2x4 that is set into the slab on grad. It was carpeted over and leads to a step down into a living area. Previous owners coverted a porch into a second living area. I want to tile the kit. / breakfast area which leads to the step down into the "family room" I think this was left over from a sliding glass door that they put carpet over. My question is if I remove it what is the best thing to use to fill in the area. I'm putting in 15 x 15 inch porcelain tiles, on a concrete slab. The Home Depot guys said to tile over it. What do you guys think? I have done two bathrooms and a laundry room in the same house with tile. This is my first "big" job almost 200 sqft and first time with porcelain tiles, my wife fell in love with these tiles, I like them too but they are 15 x 15, biggest I've used is 12 x 12. Any thoughts?


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06-13-2001, 11:00 AM

No you don't want to tile over it...bad advise.When you take it out thoroughly clean the slab where the 2 x4 was.If possible,undercut the concrete so that it looks like a dove-tail.This will make the repair stronger.You can use quik-crete concrete patching compound for this.It comes ready to go just add water.I would apply a latex primer to the surface.Makes adhesion even better. Using bricks or concrete blocks,prop up a board against the slab the length of the area to be filled.Making a "form" as it were.Fill the area with the patch being sure to "pack it so as to remove any air pockets.Smooth with a flat trowel.Be sure to follow the instructions on the patch compound container.

Once cured you're ready to embark on becoming a professional tile setter...and the guys here will walk you through every step of the way.

Stay tuned.The guys may have ideas/comments to add.

Bud Cline
06-13-2001, 01:48 PM
Tile Rookie,

If those guys at HD knew anything they wouldn't be working at HD for $7/hr. or less.

I wouldn't tile over it either. I think kalford has you on your way. If this 2X is the end of the slab (so to speak) I think I would drill a few holes in the concrete below the 2X after its removal and drop nails (pins) into those holes to help "lock" the patch into place, then follow kalfords directions.

As far as the patch material, I wouldn't be afraid to use a "u-mix" concrete product rather than something labeled as a patch. (I think this is what kalford is suggesting.) The "patch" products cost a little more. The latex primer should be used also.

06-13-2001, 02:52 PM
Once you have done as Keith and Bud suggested, find a good tile contractor supply house in your area.

What you are looking for is a polymer modified Medium bed mortar and a 1/2 x 1/2 notched trowel or larger, preferably rounded notches.

These products are designed for large body tile and will give you the support and strength you require.

When the guy behind the counter gives that strange look, ask him for his products manufacturers catalog and look in the thin set section. You will find it listed as some sort of medium bed mortar.

But make sure that it is polymer modified, other wise it won't stick to your porcelain. Latex additives are fine too but will add cost to the job.


06-13-2001, 02:56 PM
That's an excellent idea to put in the pins Bud.With that and the primer do you think a sand/cement mix will do?

06-13-2001, 02:58 PM
You can use the modified thin set as the primer for the patch, instead of buying a gallon of latex...it works just as well, and you won't have 3/4 of a gallon hanging around your garage for the next 10 years.


Bud Cline
06-13-2001, 03:06 PM

There you go again....

I have never heard of using the thinset for the primer, but of course why not. Beats the hell out of paying $25 or more for a gallon of primer when you need about a cup.

And yes, I would think once the primer is in place (especially using thinset for primer) that any old sand mix would work but maybe mortar mix would be even a little better.

I always try to install pins of some description on deals like this. They should be installed in a manner that would oppose any obvious potential movement direction.

06-13-2001, 03:18 PM
I agree...pins can't hurt a bit...but I think sand mix is easier to level out...mortar mix has such fine sand, that it tends to roll and tear under the wood float or trowel.

06-13-2001, 04:46 PM
Well if we're gonna have them use sand & cement why not just make cement paint for the primer?

Just mix portland cement and water to the consistency of paint.Brush it on coating the entire surface that the new cement will contact then pack the mortar in while the "paint" is still wet.No need to buy anything extra.

06-13-2001, 05:37 PM
True...but you're going to buy thin set anyway....every little bit extra adhesion is a good thing, don't you think?

06-13-2001, 07:44 PM
Ah yes...slight oversight on my part.

Tile Rookie
06-14-2001, 09:35 AM
Thanks! You guys are great! One more question. The wife would like to run the tile down the hallway, go figure! Adds another 68 sqft. So from the breakfast area down the hall it's 36 feet and some inches. Do you recomend an expansion joint? (installing over concrete slab) If so where? Also I plan on renting a wet saw for cutting the tile. A small area will be cut on the diagonal. The place I have rented from in the past is not sure their saws can cut a 15 x 15 on diagonal, it will on straight cuts. Said to take them to HD and get them cut, yeah right! I would prefer to cut them myself. Any suggestions. The tile store I'm getting the tile from said to take them to HD as well. Whats up with that? Thanks for all your advice, you guys are the best!


Bud Cline
06-14-2001, 11:12 AM
I just responded to this somewhere else. I think. Or am I losing it? What color was it when he do you want to think it was if.