Fascia and soffit rot
Every drop of water that lands on a roof leaves it at the same place: the edge. The fascia board and the soffit under it take that traffic for decades, and in a climate that alternates between wet and freezing they are usually the first timber on the house to go soft.
- 1 Ridge caps. Thin, exposed, and the first course to lift.
- 2 The field. The course you can see, over the underlayment you cannot.
- 3 Valleys. Leaf load mats where two slopes drain as one.
- 4 Flashing. Old masonry, and the wall an attached house shares.
- 5 Vent boots. The rubber cracks years before the shingles around it are done.
- 6 Eaves and ice dams. Where the melt runs out of warm roof and turns back into ice.
How the edge fails
The sequence is almost always the same. Gutters fill with autumn leaves and stop draining. Water backs up behind them and sits against the fascia, or overflows and runs down it. Through the winter that water freezes and thaws repeatedly in the wood and behind the gutter fasteners. The board softens, the fasteners lose their grip, the gutter pitches away from level, and the whole cycle accelerates. By the time it is visible from the ground, the damage usually extends into the sheathing behind it.
The soffit fails from the other direction. It is supposed to be the intake for the whole attic, and in a great many houses it is either blocked from above by insulation or has been covered over from below with a solid material. A soffit that cannot breathe makes the attic worse, and an attic that runs warm melts snow on the roof above and sends the meltwater straight back down to the edge that is already rotting.
Capping is not repairing
A common and inexpensive fix is to wrap rotted fascia in aluminum and cover the soffit in vinyl. It looks finished immediately, and it seals soft wood inside a jacket where nobody will look at it again.
If the wood underneath is sound, capping is reasonable maintenance. If it is not, the wrap simply hides the problem until it reaches the rafter tails, which is a far more expensive repair. On a replacement, ask that the edge be inspected with the covering off and that any soft board be replaced rather than wrapped, and that the soffit intake be opened up while the crew is there.