# Please help! How to fix hole in concrete floor before I tile tomorrow?



## JazMan (Feb 17, 2007)

So, how deep is it? Doesn't look too wide, maybe 1 1/2" max. Thin set should do it.

Jaz


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## PatrickGSR94 (Mar 2, 2011)

Well, there is no slab where the hole is. It's just the exposed dirt. Maybe some non-shrink grout, like the kind used in concrete masonry and underneath base plates of structural steel columns?


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## firehawkmph (Dec 12, 2009)

Patrick,
If you can dig some of that dirt out so your hole is at least an inch deep, get a bag of fast set concrete mix at the big box stores. It sets up in about a half hour. It won't take much to fill that hole. Just smooth it out real nice with a steel trowel so nothing is sticking up above the rest of the floor.
Mike Hawkins


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## Fantastic (Feb 21, 2011)

Not sure but don't you have to prep the original floor with a concrete treatment so any new material will bond to it??


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## PatrickGSR94 (Mar 2, 2011)

Fantastic said:


> Not sure but don't you have to prep the original floor with a concrete treatment so any new material will bond to it??


You mean for the tile? I just spent nearly 12 hours scraping the vinyl flooring adhesive off all areas that will be tiled tomorrow. I've never heard of any concrete "treatment" needed before laying tile on a concrete slab.


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## PatrickGSR94 (Mar 2, 2011)

firehawkmph said:


> Patrick,
> If you can dig some of that dirt out so your hole is at least an inch deep, get a bag of fast set concrete mix at the big box stores. It sets up in about a half hour. It won't take much to fill that hole. Just smooth it out real nice with a steel trowel so nothing is sticking up above the rest of the floor.
> Mike Hawkins


The hole is at least 2-3" deep already, from what I can see. Are there small bags of the fast setting stuff available? I don't need an 80 lb. bag or anything.

How about this stuff? Says it expands so I'm not sure if that would work for keeping the top finished surface level.

http://www.lowes.com/pd_41333-96-00...ductId=3033246&N=0&catalogId=10051&langId=-1#


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## Fantastic (Feb 21, 2011)

PatrickGSR94 said:


> You mean for the tile? I just spent nearly 12 hours scraping the vinyl flooring adhesive off all areas that will be tiled tomorrow. I've never heard of any concrete "treatment" needed before laying tile on a concrete slab.


Not for tile but for any new concrete or SLC that you use to patch/fill a hole in concrete. I believe its to ensure the new material/substance bonds to the old concrete?? Again not 100% sure about this?


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## firehawkmph (Dec 12, 2009)

Patrick,
Get the fast set concrete, use what you need and throw the rest away. I think its around $7. You don't need any special 'treatment' for the new concrete patch, or the old concrete for that matter. If you have scraped off any lumps sticking up, then go over it with your shop vac so there isn't any dust of debris. 
Mike Hawkins


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## Bud Cline (Mar 12, 2006)

...but you will need to *use "modified thinset mortar"* to install the tile. Don't use the unmodified thinset it won't bond to the remnants that are there. And don't use the premixed thinset, it won't work either.

How much did you pay for the thinset?


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## PatrickGSR94 (Mar 2, 2011)

Hey all, I just finished laying all my tile about 6 a.m. this morning  I left out 2 tiles where the hole is and will deal with it on another weekend. I just had to get the rest of the floor done ASAP so I can get cabinets and appliances back in.

I did pick up a 10 lb. pail of Quickrete fast-setting concrete the other day, and it was indeed around $7. :yes: As for the thinset, I used Mapei Ultraflex 2 modified thinset which was around $25/50 lb. bag at Lowe's.

My boss suggested sticking a piece of vapor barrier in the hole over the dirt before I put the concrete in, but I'm not sure if I can really get my hand in the hole, nor can I even see the other edges of the hole. My water heater is elevated on a platform in the garage on the other side of the wall, and the platform has drywall all around it. I dunno, I might pull that off since I've been wanting to redo that drywall on the platform anyway.

The dirt inside the hole does seem quite dry, so I'm not sure if a vapor barrier would really be necessary or not.


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## firehawkmph (Dec 12, 2009)

Sounds good Pat,
I wouldn't worry about a vapor barrier in that small of a hole. If it's dry like you say, you shouldn't have a problem. Laying tile at 6 am? You wildman you. Better start laying off the coffee late at night.:laughing:
Mike Hawkins


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## PatrickGSR94 (Mar 2, 2011)

Actually I didn't even have dinner the evening before, was working with a bucket of thinset and couldn't stop.

The little pantry room (where the hole is) took me about 3 hours to lay the tile due to the extremely tight space, shelves on both sides in the way, having to constantly sweep out debris, having to stop and make a new batch of thinset, etc. Could also be my obsessive compulsive perfectionism lol


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## FixitDragon (Feb 9, 2011)

I had this exact problem in my bathroom when I removed the vinyl to put down tile. The wet wall has a hole in the slab for the pipes, and the hole extended past the wall into the room, just like your picture, even complete with chunks of white material.

I bought bag of quick setting concrete, smallest was I think 50 or 60lbs and was $7-8

I knocked off all the loose white stuff and any other pieces of concrete that was loose. I used a wire brush to make sure all loose stuff was off and to rough up the surface, then used a vacuum to clean it.

I placed a piece of cardboard against the water pipes to act as a dam, I did not want to completely fill the hole because of the water pipes comming through

Using a spray bottle, thoroughly dampen the old surface

Prepared the quick concrete and poured it in, for my patch I needed about 6lbs.

Using the spray bottle kept the area moist while it cured.

It worked great. About 45 minutes start to finish to prep, patch and cure. By the time I had tiled up to it, it was dry and ready for modified thinset and tile over, no issues.


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## PatrickGSR94 (Mar 2, 2011)

FixitDragon said:


> I had this exact problem in my bathroom when I removed the vinyl to put down tile. The wet wall has a hole in the slab for the pipes, and the hole extended past the wall into the room, just like your picture, even complete with chunks of white material.
> 
> I bought bag of quick setting concrete, smallest was I think 50 or 60lbs and was $7-8
> 
> ...


Awesome man, I'll give it a shot this week.


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