Roof leak: what to do in the first hour

It feels wrong, but a bulging plasterboard ceiling is holding several litres of water in a bag that is getting heavier. Left alone it fails at the weakest point, usually all at once, usually over furniture.

Put a bucket underneath, take a screwdriver, and make one small hole at the lowest point of the bulge. It drains in a controlled stream instead of collapsing. You will need to replace a patch of ceiling either way; you would rather not replace the floor as well.

If water is running near a ceiling rose, a downlight or a socket, turn that circuit off at the consumer unit before you go near it. Downlights are the common route — they are literally holes in the ceiling, and water finds them.

Do not switch the light on to see the leak better. If anything has already got wet, leave it off and have an electrician look before it is used again.

Water does not come through where it lands. It travels along a batten or down a rafter and drops where the roof structure lets it, often several feet from the actual hole. This is why leaks get chased for years.

If you can get into the loft safely — and only if you can — take a torch and look for the wet trail rather than the wet spot. Follow it uphill. Note where daylight shows through. Photograph it. That trail is the single most useful thing you can give a roofer over the phone.

Yes if: water is coming in fast enough that buckets are filling, a ceiling has already come down, tiles or slates have visibly gone in a storm, or water is anywhere near electrics you cannot isolate.

It can usually wait until morning if: it is a slow drip you can contain, it only happens in heavy rain, and nothing structural has moved. A roofer working in the dark in the wet does a worse job at a higher price. We would rather come at first light and do it properly — and we will tell you honestly which of the two yours is when you ring.

A tarpaulin or a temporary cover is not a repair. It is a way of stopping further damage to the inside of your house while the weather passes and the roof dries enough to work on. Most permanent roof repairs cannot be done properly on a soaking roof.

Anyone who wants to do the full repair in the rain, at night, for cash, is not doing you a favour.

Storm damage is usually covered. Wear and tear and gradual deterioration usually are not, and insurers do look at that distinction closely. Photograph everything before you clear up: the ceiling, the trail, the outside of the roof, and the date.

If it is an insurance job, tell the roofer at the start. The report needs writing in the terms the insurer asks for, and it is much easier to do that from the beginning than to reconstruct it afterwards.