Hi,
I just bought a house in Northern California that has concrete floors throughout. I’d like to put down hardwood or laminate (Pergo or other) in some areas (currently the house has carpet or vinyl everywhere), and would like any opinions or thoughts on this subject.
The house is about 50 years old, and minor settling has occurred. There doesn’t seem to be any major cracks in the slab, but there are some areas that are not 100% level anymore. Can I put a thin, leveling coat of concrete down if necessary in order to prep for the hardwood/ laminate? Or will it simply flake off of the surface?
Thanks,
Twosheds
Replies
Is a floor out of level, or is the concrete wavy and uneven? How much variation is there from one side of the room to the other, or from the high spot to the low spot?
Hi All,
Thanks for your great advice- I've had the opportunity to get in the house now (it's in escrow), and pull up the carpets. The floor has cracks in several places, each not very wide- 1/16th of an inch at the most. The floor seems to crown, and the cracks seem to indicate the stress needed to come off of that crown. The room is about 12 feet by 16 feet, and to level the floor from from the crown to the wall might take 1/2 inch to 3/4 inch at most.
Do you think I should grind the concrete, use a self-leveler, or build up the pad, given this latest info? Thanks again for your responses in advance!
Two Sheds
I don't think you specified whether you planned to run the flooring parallel or perpendicular to the crown. This would make a big difference in how I would approach it. If you're running parallel, it may not be such a big deal to leave it as is - most 50 yr old houses have sloping floors (read 'character'). If, however, you run perpendicular, you will likely have problems at the point where the flooring changes slope at the crown. In that situation, I would probably build up the low points with something like layers of 30# felt or somesuch until I reached a point where the crown was gentle enough to accept the t&g flooring without stress.
Those self-leveling products are great, but they're also pretty spendy, especially for such a large space.
good luck!
Self levelling compound is the way to go -- concrete grinding isn't precise enough.The best leveller I've found is Mapei -- it dries harder than any of its competitors and self levels a lot better.It's best if there are two people mixing and pouring separately -- if there is too much delay between pouring batches they may not blend in properly. A 5 gallon bucket just holds one bag and sufficient water while still allowing enough room to mechanically stir [don't even think of trying to hand stir it]
IanDG
I had a similar experience with a concrete slab. Instead of bringing the low spots up, we took the high spots down with a concrete grinder. You can eaily find them at your nearest rental store. The machine has three porous stones that rotate underneath like a disc sander. With a little bit of water it was a useful machine.
I put Pergo over a concrete floor that was quite out of level and also not flat. I had received a quote from a concrete guy who'd float the floor flat and level again for $500. I spent a LOT of time working on it, and never did get it right. I was wishing I'd spent the $500.00 by the time I got to the end of it all. Since the floor wasn't quite flat, there's some small dips under the floor where it flexes when you walk, not horrible, but I always notice it. Thank goodness it's in the downstairs we rent out so I don't notice it every day.
Bottom line: whatever you do, get the floor FLAT.
If you're gonna put Pergo on concrete, spend the money for the extra thick underlayment. Its about 1/4" thick. Dont be afraid to cut pieces and double up to level a small dip. Tape all seams with duct tape. This will make the floor feel more solid under your feet.
If it's flat, but not level, then laminate or hardwood would go on fine. If it's not flat, you'll have trouble. The manufacturer has a spec for flatness, find out what it is. If you're within their spec you'll be ok, but much outside of it you won't be.
If you have a couple of bumps, then concrete grinding can work. If you have a more complex problem, then a self leveling compound is good. Tec, the tile specialty company, makes a pourable self leveling underlayment. It can work from feather thin to 1½" thick, and up to 5" thick with proper aggregate. You have to follow directions exactly. Also, it will give up moisture for quite a while afterwards, so you have to follow the flooring manufacturer's directions regarding waiting time for new concrete to dry. Not set up hard, but to dry out.
http://www.tecspecialty.com/product_list.asp?catId=1&subCatId=34