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Cement subfloor uneven for wood flooring

14 years ago

Starting to see light at end of renovation, but still issues popping up.

The cement subfloor in one recessed living room is uneven for my wood flooring (seam glue/float engineered flooring) -- by sounds of it, the job they did when they built it in 1978 wasn't that great. There are a couple small humps in it and isn't completely level in some parts (ie GC had to add some cement when installed 10 ft slider, 1/4 inch difference in height over the 10 ft).

So the options are to grind down humps and fill in small areas w/ self leveling cement. Or should I just have the whole area filled in with some self leveling cement and bypass the grinding? The area is about 260 sq ft. Also how durable is the self leveling cement, will it start to crack and break in areas that are thin? I don't want puffs of cement dust and cracking sound under the wood floors when I walk over them.

Cost -- they said it would be $250 to rent the grinder + labor but they said the cement also wasn't cheap, may come out the same in price but they haven't gotten specific numbers back to me.

Thanks

Comments (6)

glennsfc
14 years ago
You can skip the grinding and use a self-leveler, however that is dependent upon if you can deal with the added height and the cost of the product (not cheap) and you need to be skilled at applying the product.

You could grind down the high spots and then screed Ardex Feather Finish (or an equivalent) to fill in any birdbaths and low spots.
uniquewoodfloors
14 years ago
Grind the high spots. Fine sand can be good support for low spots if you will install floating engineered wood flooring.
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ruthie51
13 years ago
Just wanted to add that it's great that your contractor is preparing the subfloor correctly. In our new house, the subcontractor didn't take the time to level the concrete substrate, and ever since we moved in we've had a problem with boards not sticking. Eighteen months after we moved in, we finally had enough and hired a certfied NWFA inspector who found that there were variations in the flatness of the substrate as much as 1-1/2" over 6 feet. Now most of the floor is going to have to be pulled up and the concrete leveled and new flooring put in. We're not happy and worried how the newer flooring will flow with the existing, not to mention the mess that will be made in our new home.
glennsfc
13 years ago
1 1/2" over six feet?! Wow...and someone actually thought that would be OK?
ruthie51
13 years ago
Yep, can you believe it? That's why the installer had to come back twice and drill over 60 holes to inject glue and we still have planks coming up. In this development, the flooring subcontractor is not taking the time to level the concrete before gluing down the planks. We're having more of a problem than other homeowners because we have a wider plank (5"). At least the installer admits his mistake and is going to replace the worst areas.
xrayvision
Original Author
13 years ago
So they ended up screeding on 2 applications of "Planipatch" by Mapei - cost materials and labor for 250 sq ft room = $300. Floor just needs to be "flat", I was ok if not completely "level". The flooring store said they stand by this product and it would also be covered on their warranty for the wood flooring. (would have been more and a different material if they were to glue down the flooring to make sure the cement didn't react w/ the glue, they seam glued and floated my floor)

Would have cost $1200 to have someone come out prep the old subfloor and put self leveling cement.

Thanks everyone for help

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