How do you fix sagging or rotten wood soffit boards?
Short answer. Sagging wood soffit boards are usually refastened into the lookouts or nailers above them with corrosion resistant screws or nails, adding a nailer where there is nothing solid to hit. Rotten sections are cut back to the nearest framing, replaced with exterior grade material primed on all sides, then caulked and painted, after you fix whatever water caused the rot.
Sagging boards
- Find the framing: lookouts run from the wall to the rafter tails, usually at each rafter. A stud finder or a few test nails help.
- Push the board up and fasten into the framing with stainless or hot dipped galvanized screws or nails.
- Where boards span too far between supports, add a nailer by sliding a length of treated lumber in from an access point or removing the board to install it.
Rotten sections
- Probe with a screwdriver to find the extent of soft wood.
- Cut the board back so both new joints land on framing.
- Check the rafter tails, sub fascia and wall framing behind it; rot rarely stops at the soffit.
- Cut new exterior plywood, beadboard or PVC trim to fit. Prime wood on all sides and edges before installing.
- Fasten, fill nail holes, caulk the joints and paint.
Keep the vents
If the old board had vents cut in it, cut matching openings in the new one and install screened vents. If it never had vents, this is an easy moment to add some, since the soffit is the attic's intake. Install baffles from inside the attic if insulation sits against the deck.
Find the cause
Soffit rot in Georgia almost always starts above it: gutters overflowing with leaves and pine straw, a missing drip edge letting water run behind the gutter, or a roof edge leak. If you replace the board and leave the cause, the new wood rots too. See drip edge explained and pine needles and leaves on the roof.