Sill plates, furring strips and floor installations are among common applications for wood-to-concrete adhesion. Glue adds extra security to ensure a solid installation. Many products adhere to concrete and wood equally well, but choosing the right glue for the application is important for lasting results.
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Glue is a secondary method of attachment for bonding wood to concrete. Glue forms the initial bond, but without screws and nails, the natural expansion and contraction of the wood can break or weaken the glue. When glue is used in conjunction with screws and nails, the bond is strong enough to resist natural movement of the wood. In some applications, such as when tubing or other heating coils are embedded in concrete, fasteners such as screws or nails are prohibited, and the installation of wood to concrete must be done with glue only. Consult local building codes for proper bonding of wood to concrete in this instance. Gluing wood to concrete is not recommended when wood is considered to be below grade, or when soil extends above the wood. Exceptions can be made if the wood is moisture treated.
Sill plates are the footprints of framed buildings. The sill plate is bolted to the concrete, and it's typically not necessary to add glue. But by adding glue, the sill plate seals to the concrete and prevents air movement. For a bit more time and investment, adding glue to sill plates provides years of insulation, insurance and reinforcement. Two types of glue work well for gluing sill plates; all-purpose construction adhesive and two-part epoxy designed specifically for gluing wood to concrete. The application is the same for both products. Liberally run a zig-zag pattern of either product along the length of the sill plate before setting it. Epoxy glue systems are made specifically for concrete-to-wood applications and are more expensive. Construction adhesive is cheaper, but you can use more of it.
In most instances, hardwood flooring is never glued directly to concrete. However, advancements in engineered flooring have made above-grade wood-to-concrete adhesion possible if certain conditions are met. Check with the manufacturer of your engineered wood to ensure that it's viable with the process. In order for the glue to do it's job, specific moisture content of the slab should be established. It must be dry and many concrete slabs do not pass this test. When and if the conditions are viable, use moisture-cured urethane to bond the engineered flooring to the concrete. Two types of adhesives can be used; dry-lay should be allowed to dry to the touch before wood is placed on it. Wet-lay adhesive allows immediate placement of the flooring while the glue is still wet.
Furring is wood strips attached to a concrete wall and used as a base for nailing up wall coverings, such as drywall. Glue alone will secure furring to concrete walls, but it's typically not sufficient in most instances. Proper installations include the use of fasteners and construction adhesive to secure the strips. Fasteners include pneumatic or powder-actuated tools to fire nails through the strips into the concrete, or drilled pilot holes and expansion fasteners. Liberally add the construction adhesive to the backs of the strips, and use your choice of fastener to secure them. The drywall can then be nailed or screwed to the strips.
- The New York Times: Home Clinic: Methods to Bond Wood to Concrete
- Northrup Construction: Gluing Wood Flooring to Concrete
- Hardwood Installer: Installing Glue Down Hardwood Floors On Concrete
- Hardwood Info: Installing a Hardwood Floor Over a Concrete Slab
- Strongtie: Anchoring Systems, Sill Plate Anchor Solution
Specializing in hardwood furniture, trim carpentry, cabinets, home improvement and architectural millwork, Wade Shaddy has worked in homebuilding since 1972. Shaddy has also worked as a newspaper reporter and writer, and as a contributing writer for Bicycling Magazine. Shaddy began publishing in various magazines in 1992, and published a novel, “Dark Canyon,” in 2008.