Hanging Vinyl Siding Under Exterior Doors

Measure the bottom of the door sill with a tape measure. Add 2 inches to the measurement and cut a piece of J-channel to the measurement with a pair of tin snips.

Stand a 2-by-4-inch board on its edge and slip the J-channel over the top of the board. Measure 1 inch from each end of the top of the J-channel. Score the 1-inch mark deeply with a utility knife. Cut the notch out with a pair of tin snips and snap off the notch at the scored line.

Position the J-channel under the door sill with the edge of each notch lining up with the end of the door sill. Nail the J-channel into place with roofing nails and a hammer.

Measure 1 inch from the end of the nearest left panel of siding to 1/4 inch away from the left side of the door sill. Make a mark at the measurement on the piece of new siding. Measure 1 inch away from the end of the nearest right panel of siding to 1/4 inch away from the right side of the door sill. Transfer the measurement to the new siding panel and mark with a pencil.

Measure from the bottom of the starter strip to 1/4 inch away from the bottom of the door sill. Transfer the measurement to the new piece of siding. Draw a notch into the new piece of siding using the measurements and cut out the notch with a pair of tin snips.

Slide the bottom of the siding over the bottom of the starter strip. Push the cut notch under the J-channel at the bottom of the door sill. Attach the top of the siding on each side of the door sill with roofing nails and a hammer.