Soffit is the material that covers the area beneath eaves, while fascia overhangs the roof rafters [source: Vinyl Siding Institute]. Before you begin installing vinyl soffit and fascia, be sure to do the following:
- Read the instructions that come with the soffit and fascia.
- Nail down any loose boards, panels, shingles or tiles.
- Check that the undersides of the eaves are straight and even [source: Home Remodeling Technology].
To install the soffit:
- Nail an F-channel to the wall every 6 to 12 inches (15.2 to 30.5 centimeters), making sure the nails are centered within the channel's nail slots.
- Attach an F-channel to the bottom outer edge of the fascia board.
- Measure the distance between the channels. Subtract ¼ inch (6.4 millimeters) to allow for expansion.
- Cut the soffit panels to the measured size.
- Place the soffit panels in the channel slots so that the panels meet.
- Nail one T-channel or two ½-inch (12.7-millieter) J-channels between the panels for extra support.
- Attach F-channels or ½-inch (12.7-millieter) J-channels to the ends of each outermost soffit panel [source: Home Remodeling Technology].
To install the fascia:
- Measure the area to be covered by the fascia.
- Cut the fascia to size, if necessary.
- Punch a hole every 6 to 12 inches (15.2 to 30.5 centimeters) along the top surface of the fascia, using a snaplock punch.
- Insert the top of the fascia into the finishing trim with the bottom return leg covering the F-channel.
- Drill a hole every 24 to 36 inches (61 to 91.4 centimeters) through the fascia, F-channel and soffit groove, using a 3/16-inch bit. Then hammer a nail in each hole.
- Cut a piece of fascia cover 5.5 inches (14 centimeters) long. Skip this step if you have a corner cap.
- Mark a vertical center line on the back of the corner.
- Create a 90 degree cutout at the center of the bottom flange; each side of the cutout should be at a 45-degree angle.
- Fold the cover over the vertical center line with a hand seamer.
- Trim the ends of the cover at its corners.
- Punch the top edge of the corner cap with a snaplock punch.
- Hook the corner of the bottom ends of the fascia cover. Snap the top into place beneath the undersill trim lock [source: Home Remodeling Technology].