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thegogetter222 05-29-2012 02:37 PM

Self leveling concrete - garage conversion
I am in the middle of planning a large garage conversion to living space. 2/3 of the garage is parking space and 1/3 office space. The 2/3 part is split in half with declining slabs ending in floor drains. Can I use self leveling concrete to bring this section of the floor to level? I'd have to cap the drains but shouldn't be an issue and if this is an option I believe I could do it with a few dozen bags of Quikrete self leveling concrete. Thoughts?

mudmixer 05-29-2012 03:35 PM

How thick would be range of thicknesses for the topping?

What is going over the topping?


BridgeMan 05-29-2012 11:23 PM

You will have a disaster, trying to use this product for leveling an entire length of garage floor. Read the (fine print) instructions that come with the Quikrete self-leveling product--it will start to set in 20 minutes, meaning the first bag batched will be hard enough to stand on while you're barely batching the fourth or fifth bag. Also, I think I remember the instructions stating that the maximum thickness should be no more than 1", when I used a bag of it a few years ago. I suspect your garage floor will need a thickness of 4" or 5" at the thick end to make it level. Your estimate of needing only a few dozen bags is also incorrect--without knowing the dimensions of your placement, a good guess is that considerably more than 100 bags would be required.

thegogetter222 05-30-2012 07:38 AM

ok, fair enough. The center is no deeper than 4" from grade and the area I'm talking about is approx. 8'x8' each side. Do you think this would be cheaper buying concrete from a service and having it pumped and trialed? Any cost assumptions?

BridgeMan 05-30-2012 08:41 PM

Ready-mix concrete won't be cheaper, but one heck of a lot less grunt work. Material cost for 100 bags of Quikrete 5000 will be about $550. Going with delivered concrete, you'll be paying a small load charge if only needing just under 2 C.Y. (8' x 8' x 2 x 0.35' /27). You can avoid that by having something else formed up to pour at the same time, to make up the difference--sidewalk, driveway widening, patio addition, etc. Around here, 6-sack mud is going for $120 a yard, 4 yard minimum. A ground pump with operator will cost you another $500 or so, meaning your total will be close to $1200 if you throw in some mesh/dobies/expansion felt/curing compound.

Your local material sources and pump rental could be more or less. Just give them a call for some free quotes.

thegogetter222 05-31-2012 07:49 AM

Thank you Bridge, very much appreciated. I have a meeting with one out of the 3 contractors that I contacted tomorrow evening. He was the only one that accepted the opportunity to bid. Unfortunately, that is very common around here.

Again, thank you very much.

thegogetter222 06-04-2012 11:01 AM

Ok, I met with probably the most reputable concrete contractor in town and to my surprise the guy was VERY COOL. He basically said I had 3 options... Option 1. was to cut the concrete out and replace it. Option 2 was to use concrete to level it but he said within a few years the bond between the old concrete and new concrete could start to disintegrate and slowly lose structural integrity. He then suggested Option 3. that I simply use plywood and level it the best I could in preparation for flooring.

So he walked away with no skin in the game but an honest suggestion on a simple and cost effective solution. Awesome : )

Also note, my decline is only 1.5 from flush grade.

nealtw 06-04-2012 11:47 AM

Some other things to think about. In new construction you have 6 to 8 inches of concrete showing on the outside of the house to keep water or moisture away from the wood structure. You always have a curb wall between garage and living space also to control moisture as this curb is always waterproofed. On new constructed 2" foam is placed against the foundation from the floor level down or on the flat below the outside to feet of the floor. The foundation across the opening of the garage is not often brought up to the level of the floor so that floor moves up and down with the moisture content of the soil below.
So if you accept that the floor will be cold and may be subject to movement and moisture. The floor should not have any wood products and the bottom plates of the walls should be treated and the studs should be made slip joints like they use on log homes.
If this is going to be a perminent installation. the driveway should be cut back a couple feet the floor should be removed and the foundation at the opening should be extended up to level. Add foam around the outside and vapour barrier and pour new concrete.

thegogetter222 06-04-2012 01:10 PM

well, damn...

nealtw 06-04-2012 01:45 PM

I have done myself, just thought you should have everything before you make a decision on what you want to do.

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