The short answer
No, in most cases you should leave snow on the roof and let it thaw. A well-built pitched roof carries it, and climbing up risks a fall and cracked slates or tiles. Clear it only if something is wrong, such as sagging, new ceiling cracks or a flat roof that is visibly deep in snow, and then from the ground or with a roofer.
Why leaving it is usually safer
Snow sits on a roof the way it sits on a hillside, and a pitched roof is designed to shed or carry it. The danger in clearing it is to you. A snow-covered roof hides the edge, the gutter line and any slate that has already slipped, and a frozen surface has no grip at all. Falls from roofs are a serious cause of injury, and the work is not worth the risk for a few days of cover.
There is damage risk to the roof as well. Walking on slate or tile cracks it, and a cracked tile is a leak waiting for the thaw. Raking snow from a slope with a shovel drags at the covering and can lift the edges of slates, which the snow itself would never do.
If you are worried, the safer options are to wait, to look from the ground and to call a roofer. A roofer works with proper access, edge protection and the experience of knowing where the weak points are.
What heavy snow and ice can damage
Most roofs cope. The trouble shows up where a roof was already tired, and the winter simply exposes it. These are the places we look first.
- Gutters. Snow and ice can pull a gutter away from its brackets, particularly where the fixing screws have worked loose or the fascia behind is soft with rot. A gutter full of ice is heavy, and a plastic one can crack.
- Slipped tiles and slates. When snow slides off in a mass, it can drag a loose tile with it and leave a gap behind.
- Flashings. A flashing is lead folded into the junction between a slope and a chimney or wall. Ice working into a small gap lifts it a little further each cold night.
- Valleys. A valley is the channel formed where two slopes fall towards each other. Snow gathers there and melts slowly, so a valley with split lead or a blocked channel can overflow into the roof.
- Flat roofs. Standing water from a thaw sits where the deck has dipped or drainage is poor, and a worn membrane lets it through.
Snow also blows. Fine powder is driven through small gaps under tiles and into lofts that have no underlay, a sheet under the roof laths that stops wind-blown snow reaching the loft. It melts in the warm roof space and shows up later as a stain on the ceiling.
Ice in the gutters and at the eaves
When snow melts on the warmer upper roof and freezes again at the cold eaves, it can build a ridge of ice along the edge. Meltwater trapped behind that ridge can creep up beneath the lowest tiles or slates. This happens most readily where heat escapes into the roof space and warms the slope from below.
You can see the effect from the garden. Long icicles hanging from the gutter and a dark, wet line under the eaves both suggest that meltwater is escaping the wrong way. The usual causes are blocked gutters, a missing eaves tray or a roof that leaks warm air from the house.
Do not chip ice from a gutter while standing on a ladder. If an overflow is running down a wall, put a bucket under it and wait for the thaw. Once the weather turns, a clear gutter and a sound fascia deal with most of these problems.
When snow does need to be cleared
There are a few cases where waiting is not the right answer.
A flat roof, or a shallow roof over an extension, holds snow where a steep roof would shed it. If the ceiling beneath is bowing, a door sticks that did not stick before, or you can hear creaking from the structure, do not use that room and ask a roofer or a structural engineer to look. A conservatory roof, particularly one with a polycarbonate or older glazed covering, is also built lighter than the rest of the house, and deep snow on it is a reason to get advice.
Snow from a higher roof can also slide onto a lower roof and pile up in a valley or against a wall. In that case, it is safest to have it removed from a stable position by someone with the right equipment. Where a roofer clears it, they work from a scaffold or access platform, take it off in layers and leave the covering alone.
Never try to melt snow with hot water or salt. Hot water refreezes in the gutters, and salt corrodes flashings and fixings.
What to check after the thaw
Walk round the outside and look up. Binoculars help. Check the gutters for sagging, the ridge for a visible dip or gap, and the slope for any tile that sits lower or higher than its neighbours. Indoors, check the top-floor ceilings for fresh stains, and at the loft for wet insulation or daylight.
Photograph anything you find, with the date, because the pictures help if you want to make an insurance claim. A tile that is cracked should be replaced before the next wet spell, and our page on whether a cracked roof tile needs replacing straight away explains how to judge it.
If birds or animals were using shelter around the roof during the cold, the gaps they made may need closing as well. Our page on squirrels in the roof sets out how that is done, and the hub page on roof repairs in Bath covers leaks and storm damage. Where water is already coming in, we stabilise it first, and the survey that follows is free, with a written fixed price once we have seen the damage.
