Hardwood floors can be installed over concrete floors! Homeowners have heard warnings about excess moisture build up from putting hardwood floors over concrete but proper installation techniques can allow you to have beautiful hardwood floors with a concrete sub-floor.
Hardwood floors work best over concrete if the concrete slab is above grade or on grade, which means it is above or level with the ground. It may be very difficult to control the moisture of a concrete floor that is below grade. In this case, an engineered wood floor, made of wood glued together, may be a stronger choice.
As a natural product, wood is affected by fluctuations in temperature and humidity. Wood fibers expand and contract with these natural fluctuations, but certain types of wood and certain places on the tree are less prone to these movements. High quality wood is less likely to expand and contract in response to moisture and so is wood cut from the center of the tree. Wood cut from the center of the tree contains a higher percentage of vertical grain and is generally considered to be more durable and of a higher quality.
There are some steps you can take to make sure your hardwood floors put in over concrete will stay beautiful over time.
1.Hardwood from the supplier should be properly dried, with usual dry times being 6-12 months of air drying followed by kiln drying.
- Wood should have 7-10 days to acclimated in your home, with a relative humidity of 45 percent.
- Ask your flooring provider about stress reliefs, which are the ridges on the underside of the wood which help reduce movement.
In addition to the moisture of the wood, it is also important to keep in mind the moisture of the concrete slab. Concrete must be completely dry or the hardwood floors will get ruined from moisture build-up. The National Wood Flooring Association offers moisture guidelines and testing that can be used to determine if there is any moisture buildup in the space.
Whether installing yourself or working with a professional, once you know the height allowance, you have several options for installing your hardwood floors over concrete.
You can glue directly to the concrete, with ½ to ¾ inch height allowance. Using an adhesive product, follow the manufacturer’s instructions to spread adhesive onto the concrete, then place your floor planks directly onto the adhesive. Make sure to leave at least 12 hours of drying time before finishing the floor.
A second option is to place a layer of polyethylene onto the concrete as a moisture barrier and building a plywood sub-floor. Shoot small concrete nails into ½ inch plywood to apply directly to concrete and install hardwood plank floors over this with nailing and gluing. A plywood sub-floor tends to be the better choice if you are using planks wider than 4 inches.
Experienced flooring professionals pay close attention to managing moisture and minimizing the expansion and contractions of wood flooring. Our flooring specialists are here to help you, from start to finish. Contact us today!