When to Replace Your Roof: Ten Signs It Is Time

A concrete tile roof is generally good for fifty years plus, clay sixty or more, natural slate eighty to a hundred. But underlay, battens, nails and mortar all have shorter lives than the covering, and it is usually one of those that dictates when the roof needs redoing.

A Victorian terrace with original Welsh slate may have perfectly serviceable slate sitting on nails that turned to rust decades ago. The stone is fine. The fixings are not.

So the question is never simply how old is the roof. It is what condition are the fixings, the membrane and the details in.

If you are picking slates out of the garden every winter and having them refixed, that is nail sickness. The iron or steel nails have corroded through and slates are dropping one at a time across the whole roof.

You cannot repair your way out of it, because every slate is on the same clock. Each refix costs a call-out and holds for a while until the next one goes.

The tell is randomness. Damage concentrated in one area after a storm is repairable. Slates dropping from all over the roof in ordinary weather means the fixings have gone.

Go into the loft on a bright day and look up. If you can see daylight through the covering in multiple places, or if the underlay is brittle, torn over the rafters or sagging in shreds, the roof has lost its secondary defence.

Old bitumen felt underlay from before the 1980s becomes brittle with age and UV exposure at the eaves. Once it tears, every slipped tile becomes an immediate indoor leak.

Underlay cannot be replaced without stripping the covering, which is why perished underlay usually converts a repair discussion into a replacement discussion.

Stand across the road and look along the ridge line. It should be dead straight. A dip in the middle, a wave along the slope, or a ridge that is visibly out of line means the structure below has moved.

Causes include undersized or rotten rafters, purlins that have deflected, spread at the wall plate, or a previous covering change that added weight the roof was not designed for.

Sagging is not automatically urgent, and many older roofs carry a gentle historical dip quite safely. But it needs assessing properly, because it is the one symptom on this list that can become a safety issue.

Add up what you have spent on the roof in the last five years. If it is running at several hundred pounds a year and the interval between call-outs is shortening, you are paying a slow instalment plan for a roof you do not have.

Scaffolding is the reason this maths turns so decisively. Every repair pays for access. One replacement pays for access once.

There is also the damage you cannot see. Every leak wets timber and insulation. Repeated wetting causes rot and mould that costs more to put right than the roofing.

Replace if the underlay has perished, if slates are dropping across the whole roof, if repairs are annual, or if you are planning to stay in the house long term and the covering is past sixty.

Repair if the damage is localised, the underlay is sound, and the fixings elsewhere are holding. A well-targeted repair on a sound roof is excellent value and we recommend it often.

If you are selling within a year or two, get the roof surveyed and priced regardless. Buyers discount unknowns far more heavily than known costs, and a written report from a roofer is worth having in the file.