How often should a commercial roof be inspected in winter?

Run a full pre-winter inspection in late September or early October, a second gutter and flashing check in November, then a reduced check after every named storm or hard frost. A final post-winter survey in March completes the cycle. Roofs over 15 years old or with known defects warrant professional inspections rather than in-house checks.

What are the most common causes of winter roof leaks in the UK?

The big four are wind uplift on loose sheeting and flashings, driving rain exploiting old sealants, blocked gutters and outlets overflowing into the building, and freeze-thaw splitting at felt laps and joints. Almost all of these defects are visible during a calm autumn inspection before they fail.

Do I need a contractor for winter roof checks or can I do them myself?

Ground-level and internal ceiling checks are safe for any staff member. Anything at height should be left to trained operatives with proper access equipment, CSCS cards and public liability insurance, because iced roofs, wet moss and winter gusts make falls far more likely. Never send staff onto a roof during a storm.

How does freeze-thaw damage a flat roof?

Water works into small splits and joints in felt or edge trims, then freezes and expands by around 9 per cent, prising each defect slightly wider. Repeated every night through a cold snap, this turns hairline cracks into leaks. Fixing drainage and sealing laps before the first frost is far cheaper than spring repairs.

Should snow be cleared from a commercial flat roof?

UK building regulations require roofs to be designed for typical snow loads, so most Doncaster roofs do not need clearing. Drifts against parapets and blocked outlets are the exceptions to watch once it is safe to access. Never clear snow during the storm, and use a contractor with safe access rather than untrained staff.

What records should a facilities manager keep on roof maintenance?

Keep dated photographs of the roof each October and March, a log of every inspection, defect and repair, copies of invoices and guarantees with expiry dates, and the roof system type and age in the O&M manual. This evidence supports insurance claims, warranty disputes and dilapidations, and turns emergency spending into planned budgets.

Commercial Roof Winter Maintenance Checklist

Winter is when commercial roofs fail, and almost every failure we attend in Doncaster between October and March was visible in September. Wind-lifted sheets, blocked gutters and split felt do not appear overnight. A structured roof maintenance checklist, walked twice before the first frost and again after each major storm, prevents the vast majority of emergency callouts.

This guide is written for site managers and facilities managers responsible for industrial and commercial buildings in South Yorkshire. It covers the four winter risks that actually damage UK roofs, a working checklist you can lift straight into your own schedule, specific checks for felt, GRP and metal sheeted roofs, and a month-by-month plan from October to March.

We have maintained commercial roofs around Doncaster, Bentley and the wider region for over 30 years. Everything below reflects what actually goes wrong, not a generic list copied from a US blog.

The four UK winter risks to plan for

Wind uplift and storm damage

Exposed east-coast-adjacent sites in South Yorkshire catch the south-westerlies that sweep in from the Pennines, and gusts over 50 mph arrive most winters. Wind gets under loose sheeting, failed fixings and unsealed flashings, then peels them back sheet by sheet. Once one sheet goes, the stack effect can strip a whole bay overnight.

Driving rain

UK winter rain rarely falls straight down. It drives horizontally into verges, gutter joints, upstands and parapet details that never leak in summer. Any sealant or flashing already past its best will let water in during a sustained south-westerly system. Most "sudden" leaks we survey are old defects finally tested by driven rain.

Snow load and thaw

Heavy snow is uncommon in Doncaster but it arrives, and flat roofs hold it where pitched roofs shed it. A metre of wet snow adds real weight, and drifts against parapets can load one bay far beyond the rest. The bigger risk is the freeze-thaw cycle: water sits in a defect, freezes, expands around 9 per cent, and prises the defect open a little more each night.

Freeze-thaw attack

Repeated freezing and thawing is the single most destructive force on UK flat roofs. It splits ageing felt at joints and laps, cracks GRP edge trims and mortar, and bursts gutters and downpipes full of trapped water. Materials that were serviceable in autumn can fail across a single cold snap.

Your pre-winter roof maintenance checklist

Work through this checklist in late September or early October, before the first frost. Tick each item, date it and file the sheet. Items marked with an asterisk need a contractor or trained operative with safe access, which is where our planned commercial roof maintenance in Doncaster comes in.

Clear all gutters, outlets and downpipes of leaves, moss and silt.
Flush gutters with water and confirm every outlet drains freely, with no pooling.
Check gutter joints and brackets for leaks, sags and loose fixings.
Inspect all flashings, including Code 4 lead work and soakers, plus upstands and aprons, for gaps, corrosion and failed sealant.
Check verge and eave fixings on sheeted roofs for loose or missing bolts.
Walk the roof and look for punctures, splits, blisters and pooling water.
Check rooflights for cracks, crazing, failed caps and perished seals.
Inspect all sealant at penetrations, plant supports and duct openings.
Confirm safe access routes, handrails and any anchor points are sound.
Check interior ceilings and purlins for existing water staining, and photograph it.
Trim any trees or vegetation overhanging the roof and gutters.
Record the roof type, approximate age and guarantee status in your site file.
Book a professional inspection if the roof is over 15 years old or any defect is found.*
Agree an emergency callout route now, before the first storm, not during it.*

After every named storm or sustained freeze, run a reduced version: gutters, flashings, fixings and internal ceilings. Ten minutes of checking after a big blow is cheaper than a strip-out in February.

Checks by roof type

Different coverings fail in different ways. Match your checks to what is actually on your building, because a felt checklist applied to a steel roof misses the real risks.

Built-up felt and asphalt flat roofs

Felt is the most freeze-thaw vulnerable covering in common use. Look for splitting at laps and joints, blistering where moisture has got into the layers, and open seams at upstands and skirtings. Check the fall, because felt ponds where water cannot escape and every puddle becomes an ice patch that works the surface all winter. BS 6229 expects flat roofs to drain freely, so standing water signals a defect.

Pay special attention to outlets and gutter sole edges, the two most common leak points. If the surface is chipped or bare of grit across wide areas, the roof is near the end of its life and needs a plan, not a repair. Our commercial flat roofing services cover both felt and modern alternatives with guarantees of up to 20 years.

GRP and liquid-applied roofs

GRP fibreglass roofs are strong in freeze-thaw conditions, but they fail at the details. Inspect edge trims, joints and any penetration, because the resin bonds crack with age and thermal movement. Look for crazing or micro-cracking on older coatings, which lets water into the OSB deck below.

Check that any expansion joints and the interface with adjoining materials are still flexible. Liquid rubber and liquid-applied systems should be checked for pinholes and delamination at seams. Both systems benefit from a professional inspection every few years, as defects are often invisible from ground level.

Metal profile and composite sheeted roofs

On steel profile and composite sheeting, the fasteners are everything. Work a sample of fixings along high-load zones, the eaves, ridges and verges, checking for loose, corroded or missing bolts and perished sealing washers. A failed washer is a leak that only shows in driving rain.

Inspect the ridge and flashing details for lifted edges, check that any dry ridge and dry verge systems remain mechanically fixed, and check fibre cement or old rooflight sheets for cracks, since these become brittle with age. If the building predates 2000, confirm whether any cement sheeting contains asbestos before any drilling or cleaning, and use a licensed contractor for anything that disturbs it. Over-cladding is often the safest long-term route for these roofs.

Month-by-month winter plan

Here is a realistic schedule for a Doncaster site, assuming one site manager and occasional contractor support. Adjust the intensity to your roof age and condition, but keep the rhythm.

Month	Priority actions
October	Full pre-winter checklist. Clear gutters after leaf fall. Complete any repairs booked in September. Photograph the roof's condition as your baseline.
November	Re-check gutters and outlets after the last leaf drop. Inspect flashings and fixings. Confirm emergency callout contacts and guarantee paperwork.
December	Visual check from ground and internal ceilings weekly. After the first hard frost, check for split felt and cracked trims. Keep gutters clear through any thaw.
January	Post-storm checks after each named storm. After snow, watch for drift load against parapets and clear blocked outlets once safe. Monitor known defects.
February	The highest freeze-thaw month. Inspect flat roofs for standing water and splits. Check for new interior staining. Book contractor repairs before spring queues.
March	Full post-winter survey of the whole roof. Compile defects and costs. Schedule remedial work and planned maintenance for spring and summer.

Documentation and record-keeping

Good records protect you three ways. They prove dilapidation and insurance compliance, they support warranty claims, and they turn emergency spending into planned budgets your finance team can approve. Insurers increasingly expect evidence of maintenance before paying out on storm damage.

Keep a dated photo record of the roof each October and March, plus after every storm.
Log every inspection, defect and repair with dates, locations and the operative involved.
File invoices and guarantees centrally, and note expiry dates in your maintenance calendar.
Record the roof system type, installer and approximate age in the site O&M manual.
Report defects to your contractor in writing, even minor ones, to establish a paper trail.

A simple spreadsheet and a phone camera are enough. What matters is that the record exists, is dated, and continues year on year. If you ever sell or lease the building, that history pays for itself many times over.

Working safely at height in winter

More people are killed and injured falling from roofs than in any other construction activity, and winter conditions multiply the risk. Iced surfaces, wet moss on sheeting and strong gusts turn routine checks into serious hazards. Untrained staff should never go onto a commercial roof, full stop.

Keep winter checks to ground level and internal observation unless you have trained people with proper access equipment. Contractors should hold CSCS cards, use IPAF-certified powered access where appropriate, and carry at least £5 million public liability insurance. The HSE guidance on working at height sets out the legal position clearly.

What to do when a leak starts mid-storm

Water coming in during a storm is alarming, but the response in the first hour determines whether you face a repair or a replacement. Your priority is protecting people and stock first, the roof second. Never send anyone onto a roof while wind, ice or lightning is active.

Move stock, plant and electrical equipment out of the water path immediately.
Catch active drips with containers and sheet the area beneath if needed.
Isolate electrical circuits near the leak and warn everyone on site.
Photograph the ingress point, the water path and any damage as it happens.
Call your roofing contractor and share the photos, since they speed diagnosis.
Notify your insurer the same day if stock or equipment is damaged.

Once conditions allow, a contractor can apply a temporary weatherproof patch from a safe access platform. Temporary works keep the building dry until a permanent repair is specified, and most insurers expect you to mitigate damage rather than wait. Keep every receipt, because mitigation costs are usually claimable alongside the repair. For larger strip-ups, a skip on the highway needs a permit from Doncaster Council, and scaffolding on the pavement needs a licence, so allow a few days.

Resist the temptation to fix the defect with sealant from a ladder. Amateur repairs during winter cause a significant share of the falls and secondary damage we see, and a botched patch can trap water inside the roof build-up where it does hidden harm for months.

When to call a contractor this winter

Some warning signs need professional eyes quickly, before a small defect becomes a structural or stock-loss problem. Call a roofer if you see active water ingress, a sheet or flashing lifting in wind, daylight through the roof lining, sudden pooling where none existed before, or a gutter sagging under load. Do not send staff up to investigate during the storm itself.

We run commercial roofing repair and maintenance across Doncaster and South Yorkshire with a 0% call-out fee, IPAF and CSCS trained operatives and £5 million public liability cover. Family-run for over 30 years and trusted by more than 2,500 customers, we would rather find your defects in a calm October survey than in a January emergency. Get your winter plan booked before the weather makes the decision for you.

Common Mistakes to Avoid

Even careful site teams make the same avoidable errors. These are the mistakes we correct most often on commercial roofs around Doncaster.

Reusing degraded underlay. Patching over perished, non-breathable underlay traps moisture inside the roof build-up. The repair fails within a season or two.
Ignoring the Part L 50% rule. Replacing more than half of a roof layer counts as a thermal upgrade, so insulation must meet current standards. Budget for it before the scaffold goes up.
Mixing incompatible metals. Stainless steel fixings in contact with Code 4 lead flashings set up galvanic corrosion and eat both metals. Use compatible fixings and isolating membranes.
Skipping mechanical fixing at ridge and verge. Mortar-bedded details fail in named storms. Dry-fix systems mechanically fixed to BS 5534 stay put through the worst winters.
Hiring contractors who cannot self-certify. Firms outside CompetentRoofer or LABC registration cannot sign off Building Regulations work. You then carry the application and inspection burden yourself.

Commercial Roof Maintenance Checklist for Winter: Doncaster Site Manager's Guide