Pick up three tenders for the same unit and you may be offered three different coverings. One firm proposes layered felt, another a rubber membrane, a third wants to coat what is already there. None of them is wrong. Each makes a different bargain between what you pay now, how long it lasts and what it asks of you in between.
The trap is to read that bargain as a single number. A low price for a covering that needs replacing twice is not low. A long-lived metal roof on a building you will leave in five years may be more than you need. The right choice depends on the roof's shape, its drainage, what stands on it, who walks on it and how long you expect to keep the building.
Below we go through the main families of covering used on warehouses, shops, offices and garage blocks. We give published lifespans where we have them, typical flat roof prices from a dated national guide, and the questions that tell you whether a material suits your roof. Where a type of roof has too many variables for a typical range, we say what sets the cost instead, because your written quote comes after a survey of your own roof.
Built-up felt and torch-on layers
Felt roofing is the oldest flat covering still in everyday use. Modern versions use bitumen sheets reinforced with polyester, laid in two or three layers and fused together, usually by heating the underside with a gas torch. The top layer carries a mineral finish that protects the bitumen from sunlight.
How long does a felt roof last?
Less, a national cost site updated in March 2026, puts felt at 10 to 20 years. That is the shortest published life of the common coverings, and it varies with the number of layers, the quality of the detailing at upstands and the amount of foot traffic.
What does felt cost?
Checkatrade's September 2026 guide to flat roofing gives a typical UK range of £50 to £80 per m² for felt. Read that as a guide for flat roofs in general, mostly on homes. A larger commercial roof with awkward access or many penetrations can sit outside it, so read it as an opening figure for a conversation, not a quotation.
When does felt make sense?
Where money is limited and the roof is small, simple and easy to reach. It is also a familiar repair material, so most roofers can patch it. It makes less sense where hot works are restricted on site, because torching introduces a naked flame near the building's structure. Some contractors use cold-applied or self-adhesive layers for that reason.
Whichever route is chosen, the edges, drainage outlets and junctions decide the real life of a felt roof. A good field covering with a poor upstand will leak at the upstand long before the middle wears out.
Single-ply membranes: EPDM and its relatives
Single-ply means exactly that: one sheet of synthetic material, rolled out across the roof and joined at the seams. EPDM, a rubber, is the best known in this country. Others are made from PVC and similar plastics and are welded at the laps with hot air instead of glued. Our short guide to the single-ply roofing membrane goes into the differences.
What is the published life of EPDM?
GreenSpec, an independent building specification resource, gives an expected service life of 20 to 30 years for EPDM. Single-ply sheets also arrive in large widths, so there are fewer seams than with felt, and seams are where roofs tend to fail.
What does it cost?
Checkatrade's guide to rubber roofing, dated September 2026, quotes £80 to £100 per m² for EPDM, and puts the average at £90 per m². Ask each firm to confirm if its total carries VAT, charged at the standard 20 per cent, and whether access equipment is inside it.
Where does it work best?
On medium to large flat roofs with few awkward details. The sheet can be fully adhered, ballasted with stone or mechanically fixed, and the choice depends on the structure underneath and the wind exposure. It is lighter than a stone-ballasted system and easy to patch. The weak points are punctures, from dropped tools or from maintenance staff in hard boots, and workmanship at corners and penetrations.
If your building carries plant, aerials or solar frames, ask how the membrane will be protected under them and how future access will be arranged.
Liquid coatings and GRP
Liquid-applied systems are put on wet, as a resin or coating that sets into a continuous skin with no laps. Because there are no seams, the material flows round pipes, rooflights and awkward corners with little trouble. Nothing needs stitching or welding, so the quality of the finish depends on preparation and on the person laying it.
What about GRP?
GRP, glass-reinforced plastic or fibreglass, is one of the best known liquid-laid systems on smaller roofs. Less, the same March 2026 guide, gives GRP 25 to 40 years. Checkatrade's September 2026 fibreglass guide shows a covering-only figure of £36 per m² and around £210 per m² once the roof is fully insulated underneath. That wide spread shows how much depends on what sits under the covering.
Can an existing roof be coated rather than replaced?
Sometimes. A coating can extend the life of a sound substrate, but it cannot rescue a saturated deck, rotten insulation or a roof that holds water. A survey should test for wet insulation before anyone proposes a coating. Read our page on commercial roof coating versus replacement if you are weighing the two.
What are the limits?
GRP is rigid, so it suits roofs with a stable, well-fixed deck and less well where the building moves a lot. Surface preparation and weather decide the quality of the result, along with the skill of the applicator, because a coating applied to a damp or dusty surface will not bond. On large industrial areas, application in sections and tie-ins between them need careful planning, and the same goes for walkways, which are best laid as a separate wear layer so that foot traffic does not wear through the coating itself.
Profiled metal and composite panels
Many of the large sheds and units we see on commercial roofing jobs are roofed in profiled metal sheets, either single skin or built up as a double skin with insulation between. Composite panels are factory-made sandwiches, a steel or aluminium skin outside, an insulating core and a liner inside, fixed as one piece. Because the insulation arrives with the sheet, they go on quickly and cut the number of trades involved.
How long does metal last?
It depends on the metal and the coating. VM Zinc cites an environmental product declaration from the Building Research Establishment stating 100 years for zinc, a manufacturer's figure for a premium material that is rarely used on a standard unit. Steel sheets rely on their coating, and the common failure is at cut edges and fixings, where the coating is broken. Our guide to cut-edge corrosion explains what to look for.
What does a panel roof cost?
Prices per square metre vary too much between panel products to quote a typical range here. The cost is set by the panel thickness and core, the coating and colour, the span between supports, the height and access, and the number of rooflights and flashings. The written quote follows a survey for that reason.
When do panels make sense?
On a re-clad of a large shed, a new build or an extension where speed matters and the structure can carry the load. Joints, fixings and flashings need regular checks because they take the weather first, and a single-skin roof on a heated building will form condensation unless it is detailed carefully.
Setting life against cost
A fair comparison divides cost by lifespan and then asks what each option demands in between. The table below gathers the published figures from this post, with their sources, and adds the cost of maintenance as a question rather than a number.
| Covering | Published life | Typical UK price guide |
|---|---|---|
| Torch-on felt | 10 to 20 years (Less, March 2026) | £50 to £80 per m² (Checkatrade, September 2026) |
| EPDM | 20 to 30 years (GreenSpec) | £80 to £100 per m² (Checkatrade, September 2026) |
| GRP | 25 to 40 years (Less, March 2026) | £36 per m² covering only; around £210 per m² fully insulated (Checkatrade, September 2026) |
| Metal and composite panels | Varies with metal and coating | Set by specification after survey |
How should you read the table?
A guarantee is not a lifespan, and a published life describes a typical span, never a promise. Prices here come from national guides written mainly for flat roofs on houses, so use them to judge whether a tender is in the right area, not to price your building.
What changes the sums for a commercial owner?
Four things. First, how long you will keep the building. Second, whether the roof is a hard-working surface, with plant, walkways or solar. Third, how disruptive a replacement would be, since a roof that needs replacing less often means fewer interruptions to trade. Fourth, the cost of patching, which is cheap with felt and single-ply and trickier with some panel systems.
The best value is rarely the lowest-priced cover or the longest-lived one. It is the covering that suits the roof's falls, drainage and loading, fitted well, and checked on a schedule that you actually keep.
Weight, fire and the rules on a new covering
Changing the covering of a commercial roof can trigger rules that do not apply to a like-for-like patch. Two matter most: the weight of the new covering, and its behaviour in a fire.
Does a heavier covering matter?
Yes. Planning Portal guidance names a rise of 15 per cent or more in covering weight as a point where Building Regulations approval is required. It suggests a structural opinion before work begins, from an engineer or a surveyor. Approved Document A treats a change in roof loading of more than 15% as significant. Ballasted systems, extra insulation and added plant all add weight, so ask for the loadings in writing.
What about fire performance?
The same guidance adds a second trigger: a new covering that performs significantly differently from the old one in a fire. Boundary distances, the use of the building and any rooflights all feed into that, so ask the contractor which fire classification the proposed covering carries and keep the data sheet.
Where else do you check?
Check with your building control body before you commit. In Crawley that is Crawley Building Control, and the other councils around us run their own services. Insulation upgrades on a re-roof may also have to meet current thermal rules, which differ for homes and for other buildings, so ask who is responsible for confirming compliance.
To start the conversation, send us the address, the current covering and a few photographs from the roof edge. We survey the roof, share the photographs and follow with a single written total.
Part of our Commercial Roofing in Crawley & Gatwick
Choosing a commercial roof covering
Which commercial roof covering lasts longest?
Published lives run from 10 to 20 years for felt, 20 to 30 for EPDM and 25 to 40 for GRP, while metal depends on the coating. Treat these as typical ranges, not promises. Detailing, drainage and maintenance often matter more than the material itself.
Is a cheaper covering a false economy on a commercial roof?
It can be if it needs replacing sooner or disrupts trade each time. But a shorter-lived covering suits a building you plan to sell or redevelop. Divide the price by the expected life, then add the cost of upkeep before deciding which route gives the better return.
Can I change my commercial roof covering without approval?
Not always. Per the Planning Portal, a covering that adds 15 per cent or more in weight, or performs differently in a fire, brings Building Regulations approval into play. Ask your building control body, and have the contractor supply weights and fire data first, in writing, so the answer rests on documents.
