Lightning damage to a roof: signs, safety and repair

Lightning can start a fire that smoulders in a roof void for some time. The first job, once the storm has passed, is to look and smell for smoke in the loft, in the rooms beneath the roof and beside the chimney breast. Should you find any, get everyone out and ring 999. A loft hatch with smoke behind it stays closed.

If everything seems calm, still keep out of the loft until the weather clears, and keep away from the roof itself. Check your electrics from the consumer unit. If anything has tripped, smells of burning or stays warm, do not reset it until an electrician has looked. Sockets, appliances and the router are most at risk from a power surge, even when the roof itself seems untouched.

A strike takes the easiest path to earth, and that path often runs through the highest or most conductive part of a building. Chimneys are the usual candidates, along with ridge lines and metal such as flashings, vents and aerials. The heat can expand moisture in masonry so fast that the material splits or throws pieces outwards.

Typical damage includes cracked or displaced tiles and slates around the strike point, a split chimney pot or stack, burn marks on rafters, boards and insulation, and lead or other metal flashings that have melted or lifted. You may find fragments on the ground or in the gutters. Damage can be small and scattered, which is why a loft inspection matters as much as a look from outside.

Metal that lies near the path of the strike can be marked by it, and a pitted or blackened patch on lead, a bent vent or a split plastic pipe is worth recording even if it looks cosmetic. Hidden heat damage to the roof timbers shows up later as cracking, so note anything you see now and compare it with how things look in a month.

Do a slow circuit of the house on dry ground, looking upwards, ideally with binoculars. Note fresh gaps in the tile or slate pattern, a leaning or cracked chimney, debris in the garden and burn marks on the brickwork. Photograph anything you find, with the date. Close shots of damage help, and so do wider ones showing where on the house it sits.

If the loft is safe to enter, check the underlay and rafters near the chimney and ridge for blackened timber, a burning smell, daylight and wet insulation. Check ceilings below for new stains. A strike that damaged the covering will usually show as a leak in the next rain, so watch the house closely for several days, and look again after the first windy spell, since cracked tiles often shift later. Our page on whether it is the gutter or the roof leaking helps when you are unsure where a stain comes from.

First comes making the house watertight, because a damaged covering lets in the next shower whatever the cause of the damage. If the covering is broken, a temporary cover goes over the damage, as described in our page on emergency flat roof leaks for flat sections, with tarpaulins or boards for pitched ones.

Second is a proper survey, covering the covering, the chimney, the flashings and the timbers underneath. A chimney that has been struck needs particular care, because cracks can be hidden and a stack that looks sound can still be unstable. Third is the lasting repair: replacing broken tiles or slates, renewing scorched battens or rafters, rebuilding or repointing the stack, and refixing metal flashings. The scope depends on what the survey finds, and a charred timber must be replaced and not simply covered over.

MyBuilder's repair guide, updated in August 2026, bands storm fixes at £500 to £1,500, and a major repair at £2,500 or more. MyBuilder's chimney guide puts a stack rebuild at £2,000 to £10,000 or more. A strike that damages a stack or timbers sits at the upper end. Scaffolding is often needed, and MyBuilder quotes around £850 to £1,200 for a standard two-storey house. Those are typical UK figures and cannot stand in for a price on your own roof.

Read your policy to see how it treats lightning and what excess applies, because wording varies between insurers. We cannot say whether a claim would succeed. A survey with dated photographs gives you a clear record. See our page on hail damage to a roof for a related storm cause, and drying out after a leak for what follows.

When the roof and house are safe, we check the covering, stack and flashings, photograph each defect and put the job in a written quote at one price. We propose the lightest repair that properly deals with the damage, and a written 10-year guarantee goes with the work. Our emergency roof repairs hub explains how we treat urgent leaks. Ring 01793 626096, write on WhatsApp or fill in the form.

If you had a lightning protection system fitted to the building, mention it, because the conductor and its connections will need a specialist to test them after a strike.