From drought to deluge: what 2026’s weather has done to your roof

Most roofs fail slowly, and then suddenly. A small split in a membrane, a lap seal that has dried out, or a gutter outlet half-full of debris can go unnoticed for months. Then a storm arrives, and the problem shows up as water on the warehouse floor, a tripped electrical circuit, or stock that has to be written off.

2026 has been an unusually hard year for the roofs over Britain’s industrial and commercial buildings. First came the hottest summer on record. Then, after months of drought, the rain arrived all at once. If your building has been through both without anyone looking at the roof, now is the time to look, before winter does the inspecting for you.

A summer that broke the records

The figures are striking. According to provisional Met Office figures, summer 2026 was the warmest in the UK since records began in 1884, with an average temperature of 16.5°C across June, July and August, beating the previous high of 16.1°C set only the year before. Fifty-four Met Office weather stations, about one in seven of the network, broke their all-time daily maximum temperature records.

It wasn’t a single heatwave either. By 14 August, the UK had provisionally recorded its tenth day of the year above 35°C, a record in itself. Met Office scientists said the summer would be remembered for how dry it was, particularly in the south during July. The warmth has continued into autumn: October was the ninth month in a row with above-average temperatures across the UK.

This isn’t a one-off. The Met Office says climate change made a summer like 2026 around 130 times more likely, and it is now roughly a one-in-nine-year event. Building owners and facilities managers should plan on the basis that hot, dry summers followed by heavy autumn rain will happen more and more often.

What months of heat do to an industrial roof

A roof on an industrial unit takes the full force of the sun all day. On a 35°C day, the surface of a dark metal sheet or bitumen membrane can get far hotter than the air around it. Several things happen as a result.

Metal sheets move. Profiled steel and aluminium sheets expand in the heat and contract when it cools, every day. Over a long hot summer, that repeated movement works on fixings, loosens washers, and stresses the side and end laps where sheets overlap. Seals that were sound in spring can open up by autumn, and many won’t show it until the next heavy rain.

Sealants and coatings dry out. Mastic seals, lap tapes and coatings lose flexibility as they age, and prolonged UV exposure and heat speed that up. Once they harden, they crack rather than flex, and water gets in.

Membranes take a beating. Felt and bitumen roofs can blister and soften in high heat, and older single-ply and liquid-applied systems that are already near the end of their life tend to show their age fastest after an extreme summer.

Rooflights and asbestos sheets get more fragile. Polycarbonate and GRP rooflights become brittle and discoloured over time, and heat and UV make it worse. Asbestos cement roofs, still common on older industrial estates, become more brittle with age and weathering. That makes them more likely to crack and harder to repair safely, because every repair means disturbing a hazardous material again.

None of this is usually visible from the ground. A roof can look fine from the car park and still have dozens of small weaknesses waiting for water.

Then the rain came

After months of drought, autumn turned quickly. The UK received 138.9mm of rain in October, 13% more than the 1991–2020 average, and every UK nation was wetter than normal. Most of that rain fell at the end of the month, when Storms Austen and Boelo hit in quick succession; Storm Boelo made 24 October provisionally the joint-sixth wettest day on record for the UK.

That pattern is the worst one for a roof. Weak points opened up by months of heat meet very heavy rain in a short space of time, and the drainage system has to cope with volumes of water it hasn’t seen since spring.

Last year showed how quickly this can escalate. In November 2025, Storm Claudia brought parts of England and Wales their whole-month November average rainfall, or more, in just six days. The Midlands, Lincolnshire and Yorkshire saw more than double their usual November rainfall, which led to localised flooding and disruption.

And there is more on the way. The Met Office expects more unsettled conditions in the second half of November, with spells of rain and the potential for strong winds, and the next named storm will be called Chloe. 

Why gutters are where it usually goes wrong

If there’s one part of an industrial roof that suffers most from a hot, dry year followed by a wet autumn, it’s the gutters.

Through a dry summer, debris builds up without being flushed away: dust, leaves, moss, bird nesting material and windblown litter. It settles in gutters and around outlets and sits there, often for months. When the first big storm arrives, that debris is washed into the outlets and blocks them at exactly the moment the gutter needs its full capacity.

On many industrial buildings, the gutters are internal box or valley gutters running above the building rather than along the outside. When they overflow, the water doesn’t spill harmlessly onto the car park. It goes over the gutter edge and into the building, onto stock, machinery, offices and electrics. A single blocked outlet during a storm can do more damage in an hour than years of slow wear.

Gutter condition matters as much as cleanliness. Old steel gutters corrode, and joints and linings fail. On a 2,580m² warehouse in Swindon, the existing metal roof had severe corrosion, with paint peeling and water getting into the building. Working with Garland and CBRE, we installed a new overclad roof system with new trimline gutters and rainwater pipes. You can read the full story in our Swindon warehouse over-clad case study.

Capacity is also becoming an issue. Many gutters on older industrial buildings were designed decades ago and weren’t sized for the intensity of rain we now see. If your gutters overflow even when they’re clear, the problem may be the design rather than the debris, and it’s worth having the drainage assessed properly.

What to check before winter sets in

If you manage an industrial or commercial building, these are the checks we’d recommend before the worst of the winter weather.

Start with the gutters and outlets. They should be cleared of debris, with outlets and rainwater pipes flowing freely, and joints, linings and gutter bases checked for corrosion, splits and failed seals. If you can only do one thing this autumn, do this.

Next, look at the roof sheets and fixings. A trained operative should check for loose or missing fasteners, damaged washers, open laps and any sheets that have lifted or moved over the summer.

Check sealants, flashings and upstands as well. Flashings around plant, vents, rooflights and parapets are common leak points, and sealant that has dried out over a hot summer should be replaced before it fails.

Rooflights need a careful look too. Discoloured, crazed or cracked rooflights let water in, and they can also become a serious fall risk because they may not bear any weight. Only competent people with the right access equipment and safety arrangements should go near them.

Finally, look inside. Staining on ceilings, rust marks on purlins, damp patches on walls and puddles that appear after rain are often the first signs of a roof problem. Ask your site team to report them rather than put down a bucket and move on.

Above all, roof work should never be done by an untrained member of staff with a ladder. Work at height is dangerous, and fragile roofs and rooflights have caused serious injuries and deaths. Use an experienced contractor with the right access arrangements and safety systems in place.

Repair, maintain or replace?

Not every problem means a new roof. Often, clearing the gutters, replacing seals and making a few targeted repairs will keep a roof performing well for years. Planned maintenance is almost always cheaper than reacting to a leak after it has damaged stock or stopped production, and it gives you a record of the roof’s condition that helps with budgeting, insurance and any future sale or letting.

Sometimes, though, a roof is simply at the end of its life, and constant patching becomes a false economy. In those cases, overcladding can be a good middle way: a new roof system is installed over the existing one, usually with added insulation, so the building can keep operating. At Pioneer House in Cambridge, we installed a new design and specification-backed overclad system over the ageing roof, improving performance and extending its life without the disruption and cost of full replacement. The project included a PVC gutter lining and a 25-year warranty. Read more in our Pioneer House case study.

Where full replacement is the right answer, it can also set the building up for the future, with better insulation, new rooflights and a roof strong enough to carry solar panels later on.

The key is knowing which situation you’re in. A proper survey tells you whether you need maintenance, refurbishment or replacement, and what each option is likely to cost over the life of the building.

Don’t wait for the leak

The weather of 2026 has given industrial roofs a severe stress test. Many will have come through it with weaknesses that haven’t shown up yet. With more unsettled weather forecast and storm season under way, the cheapest time to find those problems is now, before the next storm finds them for you.

At Cambridge Roof Exchange, we look after industrial and commercial roofs across East Anglia and beyond, from gutter clearances and planned maintenance through to full refurbishment and replacement. Our HALO maintenance service is designed to keep your roof inspected, gutters clear and small problems fixed before they turn into costly leaks.

To arrange a roof inspection or gutter clearance before winter sets in, call us on 01223 782 085 or email support@cre.me.uk.