Attaching a bottom plate to the concrete slab is the first step in building walls for new construction. The bottom plate must be securely anchored to the concrete to maintain the integrity of the building.
Concrete screws are commonly used to make this connection, often in combination with an adhesive.
Powder-actuated tools and fasteners also can be used for this application, but they are not recommended for use close to the edge of a concrete slab.
Things You'll Need
- Safety glasses
- Concrete screws
- Masonry drill bit
- Electric drill
- Driver drill bit
- Caulking gun
Choose the proper concrete screw for your application. See the resources below for information on strength and capability of a sampling of fasteners.
Since bottom plates are usually specified as pressure-treated wood, choose a fastener that is compatible with the wood composition.
Put on your safety glasses.
Using a masonry bit, drill a hole into the bottom plate and concrete 1/2 inch deeper than the concrete screw will reach. For 1/4-inch screws, use a 3/16-inch bit.
Drill all the holes needed for this piece of wood. Generally, concrete screws should be placed no closer than six inches apart, and not closer that four inches to the butt end of the bottom plate.
Clean the debris out of the hole.
Use the caulking gun and spread a bead of adhesive on the wood. Choose an adhesive that is compatible with concrete and the wood composition, and rated for outdoor use.
Place the wood on the concrete and line up the holes.
Place a concrete screw in each hole, and use the driver drill to slowly tighten the screw.
Depending upon the wood type, you may want to add a washer to distribute the load across the wood. Make sure that any washers are compatible with the wood type you are using.
Clean up any excess glue.
Tips & Warnings
- Powder-activated tools and their associated fasteners also can be used. However they are not recommended for use on the edge of concrete pads due to the possibility of cracking the concrete.
- Bottom plates should be mounted with the grain of the wood curving downward. When looking at the wood from the end, the grain should "frown" rather than smile.
- Always follow any local building codes.
- If fasteners are specified on your building plans, do not substitute fasteners without the approval of the architect or structural engineer.
- Follow the wood manufacturer's specifications for fastener type and composition to reduce the risk of corrosion.
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