Can traditional hardwood flooring be laid over concrete?

Question

I was told that it can be done over a subfloor. I was also told that the subfloor should be made up of 6 mil plastic first, then plywood nailed into the concrete, then felt paper, then hardwood. Is this the proper method?

Answer 1

Some very good tips in here. Moisture test is essential, otherwise wood will absord the moisture and buckle. Also, when you say "traditional" hardwood floors, by the answers, people are thinking of different things. Even Bruce has 3 different grades of pre-stained hardwood flooring, each of which has a different install method.

However, if you mean what I think you mean, you are looking to put sand-in-place hardwood down. If this is correct, yes it is possible. Moisture test. You can put plastic down, or a trick that builders here in the Low Country use is to lay a high grady vinyl underneath to block moisture. Then you will need the plywood. Sand-in-place hardwood floors must be nailed down, never glued, so they need something to nail to. If you use concrete nails so you can skip the plywood, they will show and the floor will look terrible. You must use plywood so that the wood can be nailed with finishing nails. Once installed, sand and finish as deisred.

NOW the hard part. One step that many people do not think of is to measure how much door clearance they have. Doors and jambs are installed with a specific type of flooring in mind. For example, when we finished the basement in our last house we couldn't do sand-in-place hardwood. The space was built w/ carpeting planned. All doors were mounted at a height that would have allowed for padding and carpet, but not all the height that would come w/ sand-in-place hardwood. Long story short (too late) you need to make sure that if you add the height needed for sand-in-place hardwood floors the doors will still be able to swing.

Answer 2

If this is a basement, then you would be best to place this question to a professional contractor who can visit your home and give you specifics.

It is commonly thought a good idea to put down a sheet of continuous plastic, to prevent dust and/or water, but if there is water, (and there almost always is) there is invariably a potential for developing mould, and smells that come with it.

There are many paint-type prooducts available for use on sealing concrete floors, and using one of these would be a first step, as it would seal in dust and water, with no mould. Having nails driven through the plastic would ensure an escape route for the mould and any built-up water.

That said, you must know what amount of water exists at the moment.

You can place a sheet of plastic on the floor, and put a sheet of wood on top of it. Leave it for a full day or more, then lift and examine the floor and the plastic. If you see moisture, you will know that plastic alone is not what you need to do.


The rest of what you suggested is OK, although there are better methods.

Measure your room/floor and make a drawing of it, and show the degree of elevation, as there will be a slope if it is a basement.

Take this with you to two or more building supply stores and ask for their ideas. More than one is desirable as they will likely sell different products.

Answer 3

They must use a damp resistant underlay (usually a foam with a Silver layer underneath). This prevents any moisture coming from the Concrete subfloor into the Laminate and damaging it. An underlay is always required as without it you will have a noisy floor which is unable to expand and contract as it needs to. If you fit without an underlay it will only be a matter of time until the floor comes up. By the way if the floor is running in the same direction as the floorboards you would need to use a thicker underlay to prevent a weak point where the joins on the floorboards and flooring line up, in this case use 7mm thick green board underlay (Fibreboard) and use Polythene underneath it in the concrete section to stop moisture ingress. As long as the floor is generally flat and sound you will not need any further preparation.

Answer 4

You first need to test your concrete for moisture. Get several 2x2 foot pieces of heavy plastic and glue them to the concrete floor with painter's tape, sealing all the edges. Wait 72 hours. If moisture forms under the plastic, you need to seal the concrete floor.
You can lay hardwood directly on the concrete, but it will make for a 'noisy' floor. In order to reduce the noise from walking, you should add an underlayment as you described.

Answer 5

engineered hardwood is made to go over concrete. Do NOT use solid hardwood it will not work... With proper installation you may even get a warranty with most engineered hardwood. Contact any good flooring store in your area for complete details.

Answer 6

Here in Texas we directly glue hardwood flooring to the concrete slab. Of course, the concrete slab is poured over a continuous 6 mil poly that serves as the vapor barrier. So yes, it can be laid over concrete.

Answer 7

Do a moisture test. If it's below grade build it up like someone said using moisture barrier. But traditional hardwood, no, you can't without building it up.
If it was engineered hardwood, that would be a different story. Even then, a special adhesive is used.

Answer 8

As flywho and downtoearth suggested, do a moisture test on your concrete first. If the test is positive for moisture, you will need to seal. You will need to layer it with a vapor/sound barrier plastic material (sold at any hardware store, such as Home Depot). Then you will need to float your floor by glueing the tongue and grove of each floor piece. Make sure you use very good glue as you don't want those pieces separating on you...Good Luck.

Answer 9

Concrete is famous for wicking up water.
You method sounds great. We used three
layers of plastic in our basement and our
back room. It's on the north side. Better
now than latter....Good Luck

Answer 10

If this floor is above grade. Above the outside dirt. If it is below grade(cellar) it needs a lot more to the sub floor. IE: built up on stringers etc.,etc.. By the way, it wouldn't hurt to put a double layer of plastic down...