The short answer
Treat it as an electrical hazard first and a roof problem second. Do not touch the fitting or the switch, cut the supply to that circuit at the fuse box if you can get there safely, keep people and pets away, and call a qualified electrician. Then call a roofer to stop the water, and photograph what you can from a safe distance for your insurer.
Make the electrics safe first
When water drips from a ceiling near a light, it can run into the fitting and the wiring behind it. A wet fitting may be live, and it may stay live even when the wall switch is off, because the switch only breaks part of the circuit.
If you can reach the consumer unit, the box that holds the fuses or breakers, without crossing a wet floor, isolate the circuit that feeds that light, or the whole supply if you are unsure which circuit it is. Do not stand in water to do it. If the floor is wet and you cannot reach the box safely, stay out and ring an electrician for advice.
Keep away from the fitting. Do not touch it, do not use the switch, and do not try to dry it. Take everyone, including animals, out of that room, and keep children well away.
Ceilings can hold a surprising weight of water. A bulging or sagging patch of plasterboard can fall without warning, so do not stand beneath it. If it is safe, you may place a bucket to catch the drip, but do not go under a ceiling that is bowing. Leave the area clear until the ceiling is made safe.
Calling an electrician and a roofer
You need two kinds of help, and the order matters. The electrician checks that the wiring and the fitting are safe, tests the circuit and advises whether the fitting has to be replaced. Do not switch the circuit back on until a qualified person says it is safe.
The roofer finds and stops the source of the water. Water that reaches a light fitting has often travelled a long way inside the roof, along rafters and across the underside of the covering, so the entry point can sit well away from the stain. Our check covers the outside of the roof and then the loft, and while water is still getting in, a temporary cover goes on before anything else.
Tell each tradesperson what the other has found, since it saves time and avoids a repeat visit. If the electrician needs the ceiling opened to inspect the wiring, the roofer can say what the damp has done to the timbers and insulation above.
Do not delay the roof call because the electrics seem fine once switched off. A leak that has found one path will find it again in the next shower, and the damp can build up behind the plasterboard where you cannot see it.
Evidence for the insurer
Tell your insurer early, and gather what you can without taking any risk. The IStructE regards photographs as vital to a claim, so take pictures from a safe distance before anything is moved.
Photograph the stain on the ceiling, the fitting itself from a few steps away, the floor beneath and the whole room for context. If it is safe, take a picture of the circuit switched off at the consumer unit. Add dated shots of the roof from the lawn and any loft stains once the electrics are made safe.
Keep every receipt, including the electrician's invoice and anything you buy to protect the room. Write down the date and time, the weather, and what you did and in what order.
Do not clear away damaged materials until the insurer has inspected them or said you may, but make safe first and never put yourself at risk to preserve evidence.
Our page on how to photograph roof damage for insurance covers the full set of pictures.
Fixing the cause
Once the circuit is isolated and the roof is covered, the lasting repair can be planned. We survey the roof, photograph the faulty area and the loft, measure the damage and explain what we found. A failed flashing, a cracked tile, a blocked valley or an overflowing gutter can all send water to the same ceiling.
The repair is quoted as one written total. If the cause turns out to be condensation or a plumbing fault and not the roof, we tell you so, and the fix lies elsewhere. Our page on water stain on the ceiling shows how those causes are told apart.
Afterwards, the ceiling needs to dry fully before it is repaired, and the fitting needs to be checked or replaced by an electrician before it is used again. Rushing either step is what turns a one-off leak into a lasting problem.
The roof repairs hub covers the repairs we carry out. If water is coming in near any electrics, the page on when to call an emergency roofer explains why this belongs on the list of things that cannot wait.
