Attach a Sill Plate to a Block Foundation Attach a Sill Plate to a Block Foundation

What You'll Need
Sill plate boards
Sill sealer
Wedge anchors
A hammer drill
Hammer
Torque wrench
Tape measure
Chalk
Pencil
Safety gear {eye goggles & face shield}

Block foundations are building foundations made out of concrete blocks rather than poured concrete. Sill plates are just as parcel to the building process as they are the bottommost sections in walls of buildings and are anchored to the foundation on which vertical studs are attached. They are commonly composed of treated lumber aimed at fending off termite infestations and resisting rot and are available in various sizes. They also determine how straight and safe the structure will be, this in turn depending on how straight the foundation was during construction. You will need to first determine the best system of attaching these plates to your block foundation before you begin to attach the sill plates.

Step 1 - Measurements

Use the tape measure to determine the straightness of your foundation layer, including diagonal measurements then mark out the main part of the house using chalk. For accuracy, use the 3-4-5 method. Measure 3 feet from the corner to the side and 4 feet from the corner to the front or back. Now measure the distance between these two marks on the diagonal and if perfectly square, it should measure 5 feet. Repeat this over other sections of the house.

Step 2 - Layout

Now place the sill sealer over the block foundation wall. Make accurate measurements beforehand to ensure a proper fitting.  The seal plate should extend at most 5 inches outside the edge of the foundation wall. Now place the sill plates over the sill sealer. Sill plates cannot cover entire sections and you will also have to turn to your measurements to determine the right sizes to use as you will need to place them according to section measurements. Some contractors will argue that the sill sealer goes above the sill plates and not below. This is not preconditioned as sill sealers can be placed both above and below sill plates.

Step 3 - Holes

Use chalk or a pencil to mark out the location as to where the holes on the sill plates will be drilled. Measure at the most 3 inches from the plate board’s edge. Once you are done, use the hammer drill which should have a carbide-tipped masonry bit to create the holes. Note that these holes should be the same diameter as the wedge anchors that you are about to install.

Step 4 - Anchorage  

Place the wedge anchors into the drilled holes on the sill plates and use the hammer to secure them, ensuring that the washer and nut which are part of the anchors are in contact with the plates. Use the torque wrench to secure the anchors in place. Locate the next set of holes and repeat the process, placing the seal sealer below as you go along. Make sure that these plates are butted together.

NOTE: Remember to wear your safety gear when working on a project like this.

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