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Glue Down Hardwood Floors on Concrete

If you want to install flooring on a concrete slab, your floor-covering choices are limited. You can’t nail solid-wood flooring to concrete without first installing a plywood subfloor. Floating floors are an option, but some people don’t like their hollow sound. Carpet is a good alternative if the slab’s moisture is taken care of (see “The Stay-Dry, No-Mold Finished Basement”). But to get the look and feel of real wood, the best thing to do is to install engineered hardwood flooring.

How Are They Installed?

Glue downs are installed by trowel spreading of adhesive on the subfloor in a pre-determined area (shown). Usually, professionals will measure out three feet or enough for twelve rows to cover, using a three-inch wide board as an example. Each and every individual board is placed one at a time into the adhesive until the glued area is covered. Once completed, another area is marked and laid.

Not All Types Of Hardwood Should Be Glued

Contrary to what you may hear, not all products can be glued easily. Put another way, gluing solid 3/4″ hardwood has always been a risky business, but some premium urethane glue manufacturers will warrant their use. The difficulty encountered with solid hardwood is the lack of flexibility compared to more engineered products that are glued.

Higher Quality Engineered – Ideal For Wide Plank

Common types used for gluing down are engineered hardwoods. Quality hardwood thicknesses vary from 3/8 inch up to 3/4″ depending on the manufacturer. During manufacturing, the bottom sides of many products are milled with relief cuts (below). This ensures the flooring can bend to minor irregularities in the contour of the subfloor it is being installed while increasing the bonding contact with adhesive at the same time. This is definitely not an excuse to skip floor preparation; stressed heavily on this site.

Pros and Cons Of Gluing

Most consumers prefer the solid feeling of hardwood floors underfoot. Floating floors for the most part do not offer this benefit unless a premium underlayment is used and a very flat subfloor is maintained prior to installation. After the addition, some still complain of the hollow effect floating floors exhibit. A properly glued hardwood floor will feel and sound very much like a traditional solid floor.

How Long Does It Take To Install? Are Adhesives Toxic?

Assuming we have a 400 square foot, square room with furniture moved and everything is ready to go, one experienced installer can complete a 3-inch wide glue-down installation in 10 -12 hours. Adhesives used today are predominantly three types. Water-based, urethane-based, or acrylic, with the most often used urethane.
Older more toxic adhesives are long gone, with newer more environmentally friendly varieties. If you are chemically sensitive it may be wise to vacate the premises when work is being done. With glue downs, curing time is typically one day or an overnight period before furniture can be moved back into place.

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