The advent of vinyl siding has allowed homeowners with average do-it-yourself skills to change the look of the exterior of their home more easily than other siding methods such as wood, brick or stone. Many accessories, including trim, soffit and fascia, are available for a vinyl siding job. A soffit is the horizontal surface under a roof overhang. When covering a porch ceiling, you can use the same materials used to cover a soffit.
Observe the underside of the ceiling you plan to cover. Ensure the ceiling surface is solid enough to hold nails for the soffit installation. Remove all existing moldings from the edges of the ceiling with a pry bar and a hammer.
Install 1-inch by 3-inch furring strips to the perimeter of the ceiling and every 16 inches on center perpendicular to the ceiling joists if the ceiling is not solid or if you plan to mount the soffit to bare joists. Nail the furring strips up using 8d nails and a hammer. Skip this step if the ceiling is solid enough to mount the soffit to directly.
Mount lengths of "J" channel to the perimeter of the ceiling with roofing nails and a hammer. Ensure the open end of the channel is facing the interior of the ceiling. Butt pieces of "J" channel together if needed for longer areas. Cut pieces to length as needed with tin snips.
Lay out the soffit panels to line up with existing siding or soffit work if desired. Measure the length of the first piece by measuring inside the "J" channel from one side of the ceiling to the other. Subtract ¼-inch for expansion and contraction. Cut the soffit pieces to length with a hack saw blade or tin snips.
Insert the first piece of soffit into the "J" channel on the ceiling. Push it all the way to the edge, leaving approximately ¼-inch of clearance. Secure the piece by driving roofing nails through the nail slots in the soffit to the ceiling or furring strips underneath. Nail every 12 to 16 inches.
Cut and slide the remaining soffit panels into place in the same fashion. Allow ¼-inch for expansion when you reach the last piece at the end.