How to Flash a Bottom Plate to a Wall

Sills are one of the main building blocks when framing a wall. They run horizontally along the bottom of the wall and attach to the studs that run vertically to frame out a house or room addition. These plates are made of 2-by-4 lumber and come into contact with the ground. This can cause rot over time. One way to help prevent that and also help stop water from entering the house is to install flashing over the sill plate. This flashing can easily attach and help keep the wall framing strong for a longer period of time.

  1. Measure the area of the opening where the flashing will be installed. Run a tape measure across the length of the opening.

  2. Measure the width of the sill, and add an extra half inch for the flashing to extend down toward the outside of the house. This will help prevent water from entering the house.

  3. Lay out the flashing along the sill.

  4. Mark on the flashing where cuts for the length or width will need to be made.

  5. Cut along the marks with tin snips, and leave an extra 1/2 inch in the width for the flashing to fold over.

  6. Set the flashing back on top of the sill plate to make sure it fits properly.

  7. Spread out construction adhesive over the bottom of the flashing with a margin trowel. Cover all of the flashing, and set it down on the sill plate.

  8. Press down firmly on the flashing so it can adhere to the sill plate, and run your hands over the flashing to help it adhere.

  9. Fold down the 1/2 inch strip along the outside of the house, and press it in place.

  10. Wipe off any excessive construction adhesive that squirted out from underneath the flashing with a clean rag.

  11. Inspect the area to make sure there is no more adhesive, and verify that the flashing is properly installed.

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