Can a roof be inspected in the rain?

A leak that only happens in a certain kind of weather is hard to catch on a dry visit. Rain on a roof turns a suspicion into evidence, and that is the strongest argument for being at the property while it falls. Standing in the loft with a torch during steady rain, you can see water tracking along a rafter, dripping from a nail tip or darkening felt at a lap, and you can follow it uphill to its source.

Outside, the gutters tell their own story. An overflowing gutter at a corner, water pouring over the front edge of a blocked valley or a downpipe that spits instead of runs are all faults you can only judge when water is moving. Rain also shows where a flat roof holds ponds, because the puddles are there to be measured and recorded where they sit. A flat roof that drains within a day of rain is behaving differently from one that is still holding water two days later, and the second one is the one to worry about.

None of this needs a ladder. It is a ground and loft inspection, and it can be very useful. The service overview on roof inspections and surveys shows how the wet and dry parts fit together.

The close inspection of the covering is a different matter. A wet slate or clay tile is slippery, moss turns to grease, and lead and felt are no better. Nobody should walk a pitched roof in those conditions, and a ladder against wet render or a wet fascia is a poor risk too. Wind often comes with rain, which makes it worse.

Visibility suffers as well. Water films hide hairline cracks in tiles, and a wet surface hides the pale line where a slate has slipped. Mortar on a ridge or verge looks the same colour whether sound or perished until it dries. Photographs taken in rain are grey, speckled with drops and rarely clear enough to show the detail you need to see before agreeing a repair.

For those reasons we separate the two jobs. The inside and the ground-level checks go ahead in wet weather when there is a leak to trace. The detailed work at roof level waits for a dry spell.

Water rarely comes through the ceiling directly below the hole in the roof. It runs along felt, battens and rafters before it drips, so a stain in the back bedroom can start a metre or two away. The loft visit in wet weather is where that distance gets measured, and it is why we ask you to leave the loft hatch accessible and clear of boxes.

Useful clues include the timber that is darkest or wettest, a trail of tide marks on the felt, and wet insulation sitting below a fixing or a pipe. Condensation can mimic a leak, so we note whether the dampness appears only on cold mornings or only during rain. Our page on damp in the loft explains the difference in more detail.

If water is coming in now, photograph it, set a bowl or bucket underneath, shift furniture and stored boxes out of the way, and ring us on 01793 626096. An active leak jumps the queue with us, and what comes first is limiting the damage, with the lasting repair planned afterwards.

After the wet visit, the second stage is a dry one. With the surface dry, someone can walk the slopes or work from a ladder, handle the tiles, test the ridge and hip fixings, examine the gable edges and the lead at the chimney, and take sharp pictures of each fault. Pole cameras and drones can add to this on awkward roofs; our guide to roof inspection methods explains where each suits.

If you are weighing up a visit now or later, the practical rule is easy. For an active leak, the wet-weather loft check is worth having because it points to where to look. For a routine check, a condition report or a pre-purchase look, wait for a dry day and the result will be clearer. A written quote follows the survey either way, with photographs of your own roof.

If the water is coming through a flat above you or a roof you do not own, the same rule applies, but the practical steps differ. Photograph the stain with a date, tell the managing agent or freeholder in writing, and make clear that the leak is happening in wet weather and can be seen. Our page on who is responsible for a leasehold flat roof covers where that responsibility normally sits.

Do not climb out onto a flat roof in the rain to look for the cause. A flat roof is slippery in the wet, and the edge is easy to miss. Leave that to the visit, and keep your evidence from inside.

Date every photograph, note the time the drip started, and write down which rooms were affected. If several flats in the block are wet, say so in your message, because that points the agent towards a roof-wide cause rather than a single bad joint.

Rain is only one of the conditions that affect an inspection. Strong wind makes ladder work and pole cameras unsafe even when the roof is dry, and a frosty or icy morning makes slates and flat roofs treacherous long after the rain has stopped. A thin layer of ice on a lead flashing is invisible until a boot slips on it.

For that reason we decide on the day. If the weather is wrong for climbing, we do the parts that can be done safely, which usually means the loft, the gutters from ground level and the outside from a distance, and we arrange the roof-level work for a suitable day.