How do I test a cement sub-floor for moisture?

Question

I want to install wood floor myself over a cement sub-floor and the guy at the store wants me to pay and have him test the cemet for moisture. If he detects moisture then he puts some special sealer on the floor and then I can lay the wood directly onto the floor using glue.

Answer 1

take some clear plastic, 2ft x 2ft and tape it to the floor, wait 24 hrs check for moisture, easy. good luck

Answer 2

Are you having the floor installed by a professional installer? If so make the installer responsible. If you decide to pay for the testing make sure there is a warranty for the test. Does the tester know what hes is doing or just taking your money. what does the manufacture of the wood recommend. Some will warrant the wood for moisture problems some don't. Be sure you are getting engineered wood not solid wood. Some wood are made for installing on concrete even in basements. The plastic square left over night is a good start. If in doubt seal the slab. Better safe than sorry

Answer 3

Testing for moisture is rather a useless test. That because you have no idea of when your area of the country will experience a rather wet and unusual summer where the rainfall might be triple or quadruple of the normal rain fall. So its a useless test to even do. I suggest you go and buy the sealer yourself, its a two part epoxy and seal off that floor by mixing and rolling the material on with a regular paint roller. The cost for a 20 x 20 foot space will run about $40 and it assures you that your wood floor will remain flat and free of that seeping moisture thru the concrete at a future later date when it will become abnormally wet in your locality.

Answer 4

Many flooring companies now require their installers or subcontractors to perform a moisture test prior to installation. You can do this yourself with a calcium chloride test. They cost about $10. Moisture readings must be below 3lbs. per 1000 sq. ft. to qualify a floor for acceptable hardwood installation. Taping a piece of plastic to the floor will only reveal extreme moisture problems. There are also instant moisture reading meters but they are quite expensive. If you use a calcium chloride test, follow the instructions very carefully or you will get an inaccurate reading.

Answer 5

Where are you located. If you are putting hardwood ona concrete floor seal it no matter how the test comes back( dont pay for a unnecessary test). The things you would need to worry about are ... in the event that there is excessive moisture are.. where does the roof water drain to? full gutter helps with the proper extensions. How close are your sprinklers to the house? Is the grade around the house sloped away properly in all areas? Where is the water heater located and if it leaks where does the water go?

Countless other questions to consider.

Answer 6

I would check with the flooring manufacture on what there "MVT" "Moisture Vapor Transmission)levels are. In "VCT" tile it is under 3 lbs. per 24 hours. The plastic test is a start, but the correct test is a "Cal-Test". They are manufactured by a company called "Vaprecision" and there web site is: www.vaportest.com
If you purchase an epoxy that stops "MVT", make sure what there guidelines are & warranty.

Answer 7

tape down a square of plastic on the cement and leave it for about a week pull up the plastic if there is moisture on the plastic or floor you need to seal it.
you may want to look at a raised sub floor with a vapour barrier

Answer 8

I believe I would go ahead and apply the sealer,because wood flooring is pretty expensive and you don't want to redo it in a couple of years...

Answer 9

Construction "critical path" would be to leave the subfloor off until the basement slab is poured. Reason for this is access by the cement truck chute to "spread" the concrete. Once the slab is poured, subflooring can be installed on the 1st floor.