How do I tell if my soffits or fascias are rotten?

The signs of rot in eaves timber, what to check and from where, and the difference between a repairable board and a full replacement.

Difficulty: beginner
Time: 45 min
Read: 4 min
Safety: warning

Short answer

Look for paint blistering, dark staining, sagging gutters, and daylight or gaps at the soffit. Test with a bradawl at the joints and the ends — if it sinks in more than a few millimetres, that timber has gone. Rot is usually worst behind the gutter where nobody looks.

Fascia and soffit rot is progressive and mostly invisible. By the time the front face looks bad, the back and the top edge have usually been wet for years. Catching it early is the difference between a splice repair and replacing a whole elevation.

Safety

Inspecting eaves means ladder work. Set the ladder at about 75 degrees on firm ground, foot or tie it, use a stand-off, and never lean sideways to reach. Much of this inspection can be done from the ground with binoculars, which is safer and often just as informative. Do not stand on the gutter or push against the fascia to test it — that is how people fall.

Step by step

Start from the ground with binoculars.Look along each elevation for sagging gutter lines, dark staining below the gutter, blistered or missing paint, and any soffit board that has dropped or bowed. This tells you where to go up.
Look for the water sources.A blocked or leaking gutter, a missing eaves protector letting roof underlay drain behind the gutter, a slipped tile, or overhanging vegetation keeping the eaves permanently damp.
Check the paint condition.Blistering paint on timber almost always means moisture underneath. Flaking on the underside of a soffit is a stronger signal than flaking on the face.
Test with a bradawl at the vulnerable points.The ends of boards, the joints between lengths, the bottom edge, and immediately behind the gutter. Push gently. Sound timber resists; rotten timber takes the point easily.
Check behind the gutter if you safely can.This is where the rot usually is, and where nobody looks. If the gutter can be released safely at one point, look at the fascia behind it.
Look at the soffit ventilation.Blocked or absent soffit vents mean the roof space is not ventilated, which causes condensation that wets the eaves timber from inside. Check the vents are clear.
Check inside the loft at the eaves.From inside, look at the eaves for damp staining, mould on the timbers and daylight where there should not be any. Damp at the wall plate is a serious sign.
Judge the extent.Isolated soft patches at a joint or an end can be cut out and spliced. Rot along the length of a board, or several boards on one elevation, means replacement of that run.
Get a quote before deciding on uPVC.Capping rotten timber with uPVC covers the problem rather than solving it. Replacement with new timber or full uPVC on sound bearers is the honest choice.

Tips

Do this inspection in autumn after the leaves have dropped and before the winter weather. It is the ideal time to catch a blocked gutter as well.
Photograph each elevation from the ground each year. Comparing photographs over time shows deterioration that is invisible day to day.
Birds getting into a soffit is a strong indicator of a hole you have not found.

Common mistakes

Capping rotten timber with uPVC boards — It seals wet, rotting timber behind a plastic face where it cannot dry and cannot be seen. The rot continues, and it eventually reaches the rafter feet, which is a much bigger repair.
Judging the condition from the front face only — Fascias rot from the back, where the unpainted timber sits against the gutter and the roof edge. The front face is the last thing to look bad.

If it doesn't work

Paint blistering along the bottom edge of the fascia

Cause: Water running behind the gutter — Fix: Fit an eaves protector tray so the roof underlay discharges into the gutter, and clear the gutter. Then deal with the timber.

Soffit board sagging or dropped

Cause: Rot at the fixings, or the bearer behind has failed — Fix: This needs opening up. A dropped soffit usually means the timber it fixes to has gone as well.

Birds nesting in the eaves

Cause: A gap where a board has rotted or shrunk — Fix: Find and repair the gap after the nesting season — nesting birds are legally protected and the nest must not be disturbed while in use.

Damp on the loft side of the wall plate

Cause: Long-term water ingress at the eaves — Fix: This is beyond a fascia repair. Get the roof edge properly inspected — the rafter feet may be affected.

Questions people ask

Should I replace timber fascias with uPVC?

It is a reasonable choice provided the timber behind is removed or proven sound, not simply capped over. Capping is cheaper and stores up a much larger problem.

How long do timber fascias last?

Well-detailed, painted on all faces and kept clear of a leaking gutter, thirty years or more. Painted only on the front, with a gutter that overflows, ten to fifteen.