The short answer
Rotten fascia boards are soft, dark, crumbling or flaking timber, usually caused by water from a leaking gutter, a failed paint finish or water running behind the board. Rot should be cut out, not painted over. Boards that are mostly sound can sometimes be repaired, while badly rotted ones are replaced, ideally with a protective eaves system so the new boards stay dry.
What causes fascia rot
A fascia is a board fixed to the ends of the rafters along the eaves. It carries the gutter and covers the rafter ends. Because it sits at the edge of the roof, it is exposed to rain and sun, and it takes water from several sources.
A leaking or overflowing gutter is the leading cause. Water that drips from a joint or spills over the back of the gutter runs straight down the board, and a board that stays damp rots. Paint that cracks lets water in at joints and end grain, and a board with no protective finish soaks up moisture.
Water also arrives from above. If the roof covering ends before it reaches the gutter, or the eaves felt is missing, torn or tucked in behind the gutter, rain runs behind the board. Poorly sealed joints between boards, nail holes and gaps at corners let in more.
Poor ventilation at the eaves contributes. Condensation in the roof space can reach the rafter ends and the back of the board, and BS 5250:2021 is the current code on managing moisture in buildings. A blocked soffit vent or insulation stuffed against the eaves keeps the timber damp from behind.
Timber quality counts too. Softwood boards that were not treated, or that were fitted with the end grain exposed, decay faster. Rot is a living process: once a board is wet for long enough, fungi take hold and spread.
Testing the timber
Look first from the ground. Peeling or blistered paint, dark patches, splits along the grain, a board that bows or has a wavy edge, and a gutter that sags are all signs. Green or black growth and fungi on the board show it has stayed wet for a long while.
Then probe. A screwdriver pressed into the timber meets resistance in sound wood. In rotten wood it sinks in, and the wood crumbles or feels spongy. Test several places, including the bottom edge, joints and the ends, where rot often starts. A good board can be painted or repaired, and a soft one cannot hold a fixing.
Check what lies behind. A rotten fascia often means damp rafter ends, a rotten wall plate or damaged soffit. Where capping boards cover old timber, rot can run unseen for years, and a sound-looking plastic face may sit on soft wood.
Brackets give clues. If gutter brackets have pulled loose or the screws turn without gripping, the timber behind is likely soft. A gutter that hangs from rotten timber will fall as soon as it is loaded with water.
Do this safely. The fascia is at the top of the wall, so use a stable ladder or tower, and leave the testing to a roofer where you cannot reach it safely. Our page on fascia capping against replacement explains the choices.
Repair, replace or cap
The right course depends on how much is rotten. Small areas of surface rot in an otherwise sound board can be cut out and filled with a repair compound, or a short length spliced in. That suits a good board with a local fault.
Where the board is soft along much of its length, or the rot has reached the rafter ends, replacement is the sound answer. The old board is removed, rotten rafter feet are cut back and repaired or spliced, and a new board is fitted to firm timber. The new board can be timber, primed and painted on all faces including the ends, or uPVC or another cladding.
Capping means covering the existing board with plastic. It is quick and gives a low-maintenance face, but it hides the old timber and traps damp against it. Capping over rot is a poor choice, because the decay continues behind. It suits boards that are sound and only need a new face.
Eaves protection helps new boards last. An eaves protection system, such as a support tray and felt that leads water into the gutter, stops rain running behind the board. Our page on the eaves protection system describes how it works.
Soffits tend to be renewed in the same visit, because they age alike and share the same access. Because the HSE lists asbestos insulating board among the materials once used for external soffits, old ones are checked before they are drilled or broken.
Our approach and the cost drivers
On a survey we probe the boards, look behind where we can, check the gutter for leaks and the eaves for felt and ventilation, and photograph the faults. You see the picture of what has failed and why.
We tell you whether repair, replacement or capping suits the condition, and what else needs doing to stop the rot returning, such as mending a leaking gutter or fitting eaves protection. We do not cap over rot.
Cost depends on the length of board, the amount of rot found, the material chosen, whether gutters are rehung or replaced and the access. MyJobQuote's figure for capping fascias and soffits is around £800 on a three-bedroom semi (MyJobQuote, Sep 2026), and replacing boards with timber repairs behind costs more. Scaffold, where needed, is a large share of the price.
You receive one written total, with access and VAT stated. If the frame will stand on the road, the scaffolder arranges the licence with us.
Treating a leaking gutter early prevents most fascia rot. The gutters, soffits and fascias hub covers the whole roofline, and boards that are caught while mostly sound cost much less to put right.
