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How to Build Roof Gable End Cornice Returns

A cornice return is sometimes called "a cornice" or the "fascia return," and squares off a corner on the roof where it meets the soffit. When building cornice returns it's important to caulk all seams at the peak of the gable and between the fascia boards and cornice to prevent water from entering and rotting the wood. Many do-it-yourselfer's with basic carpentry skills can successfully complete this project in an afternoon.

  1. Measure the area from the end of the gable fascia to an area approximately 6 inches underneath the roof beam at each end of the roof using a tape measure.

  2. Mark a piece of plywood in a triangular design to fit the area you measured in Step 1 using a framing square. The triangular wood becomes the cornice. Repeat for the other end of the roof.

  3. Cut out the cornice pieces using a circular saw and straight-edge guide. You need two cornice pieces.

  4. Test-fit the cornice pieces over the ends of gable on the roof. Install using finishing nails and a hammer into the ends of the beams driven up into the underside of the gable fascia.

  5. Embed the heads of the nails below the surface of the wood using a nail set. Be careful not to split the cornice pieces.

  6. Caulk the seams between the fascia boards and the cornice using silicone caulking and a caulking gun.

  7. Finish the cornice returns by siding them according to the manufacturer's directions.