The roofline is the strip of the building that nobody looks at until water is running down the wall. It does three jobs: it finishes and supports the bottom edge of the roof covering, it carries rainwater away from the building, and it closes and ventilates the eaves. When any of those fails, the damage happens to the wall and the timbers rather than to the roof, which is why the repair bill is so often larger than people expect.
What each component does
The fascia is the vertical board across the ends of the rafters. It closes off the roof structure, provides the fixing for the gutter, and supports the bottom course of tiles or slates. If the fascia is failing, the gutter it carries is failing too, whatever condition the gutter itself is in.
The soffit is the horizontal board underneath, running from the fascia back to the wall. On most modern roofs it also carries the eaves ventilation, either as a continuous strip vent or as individual circular vents.
The gutter and downpipe do the obvious job, and the bargeboard performs the same closing role at a gable verge that a fascia does at the eaves.
How to tell yours are failing
Almost all of this is visible from the ground, particularly during heavy rain, which is when it is worth going outside for two minutes with an umbrella.
- Water spilling over the front or back edge of the gutter in rain
- Green or black staining running down the wall below a joint
- Gutter sagging between brackets or visibly holding water when dry
- Fascia board soft, split, flaking paint, or with visible rot at the ends
- Soffit boards sagging, discoloured or with holes where birds get in
- Plants growing in the gutter, which means it has silted up completely
- Damp patches on internal walls at first floor ceiling level
Why a leaking gutter is more serious than it looks
Water overflowing at the eaves lands on the wall below and on the fascia and rafter feet above. Repeated saturation of brickwork drives damp inside, and repeated saturation of timber rots the ends of the rafters, which is structurally the part of the roof you least want failing.
It also causes disproportionate damage in winter, because saturated masonry that freezes spalls the brick face. A dripping joint in October can be a repointing job by March.
For that reason we treat a persistently overflowing gutter as an urgent small job rather than a cosmetic one, and it is usually cheap to fix if it is caught before the fascia has gone.
uPVC, aluminium or cast iron
Modern uPVC is the standard replacement on most houses: light, unaffected by rot, low maintenance, and available in profiles and colours that suit almost anything. Good quality board with a proper capping lasts a long time; the cheapest thin board can distort and discolour.
Aluminium is the middle ground, particularly for larger properties and commercial buildings, and seamless aluminium gutter formed on site removes most of the joints that leak.
Cast iron matters on period and listed buildings, where plastic guttering visibly changes the character of the elevation and may not be acceptable in a conservation area. Existing cast iron can very often be repaired, rehung and repainted rather than replaced, which is usually the right approach on a historic building.
Do it while the scaffold is up
Roofline work needs safe access at eaves level along the whole run of the building. On a re-roof that access is already paid for, so the marginal cost of renewing fascias, soffits and gutters at the same time is far lower than doing it as a separate job later.
There is a practical reason too. The bottom course of the covering sits on the fascia, so replacing the fascia afterwards means disturbing the roof edge you have just paid to renew. Doing both together means the eaves detail, the ventilation and the drip into the gutter are all set up correctly in one go.
If a re-roof is a few years away and the roofline is failing now, it obviously cannot wait. But if the two are close together, plan them as one job.
Common questions
How often should gutters be cleared?
Twice a year suits most properties, in late autumn once the leaves are down and again in spring. Anything under trees needs it more often, and the autumn clear is the important one because winter rain is what does the damage.
Can fascias be capped over rather than replaced?
Capping puts a plastic cover over the existing timber. It looks tidy and it is cheaper, but if the timber underneath is rotten it stays rotten and now cannot be seen. It is only reasonable where the existing boards are demonstrably sound and simply tired.
Why does my gutter overflow when it is not blocked?
Usually a fall problem or an undersized outlet. Gutters need a consistent fall towards the downpipe, and brackets sag over time. Sometimes the roof simply discharges more water into one section than the outlet can take, particularly where two slopes meet a single valley.
Do you replace cast iron with cast iron?
Where the building calls for it, yes, and often the better answer is to repair, rehang and redecorate the original ironwork rather than replace it. On a listed building or in a conservation area that may be the only acceptable route.