Ask five roofers which material is best for a commercial building and you may hear five answers, because the true reply is that each one wins in some places and loses in others. A material that suits a warehouse with a sound steel frame can be wrong for a shop whose old flat roof moves with the seasons. What matters is how a material behaves once it is on your roof: how long it tends to last, what it costs to put down, how well it copes with foot traffic and ponding, and what it needs from you each year. The comparison below uses published lifespans and cost ranges, quoted as typical figures that shift with exposure, workmanship and upkeep, and never as a promise. Where a source is thin, the text flags it. The aim is to help you read a quotation, not to pick for you. The roof itself, once surveyed, settles the choice.
How to compare one material with another
There are four things worth putting side by side. The first is life, meaning how many years before the covering needs replacing, as opposed to repairing. The second is the cost to lay, which should include the preparation and the edges, not only the sheet. The third is maintenance: how often it needs attention and what that attention involves. The fourth is fit, because a material that is excellent in one setting can be poor in another.
Life figures need care. A manufacturer's guarantee is not a lifespan, and an installer's guarantee is neither. Lifespan figures published by trade bodies, suppliers and cost guides also disagree with one another, sometimes widely, and they assume the roof is detailed correctly and kept clear of debris. A cheap material laid well on a sound deck will often outlast an expensive one laid badly on a damp one. When two sources conflict in the table below we give a range that spans them, not a single number that looks more certain than it is.
Cost needs the same caution. The only commercial rates we could source come from one contractor's published answer on a cost-comparison site, so we treat them as indicative. Commercial roofs vary so much in access, edges, drainage and insulation that they are priced from a survey, and we say where those factors push the figure up. Your fixed price follows the survey.
Finally, think about the whole life of the roof and not the day it goes on. A covering that costs more now but needs no attention for a long time can be cheaper than one that must be recoated, resealed or patched regularly. Equally, a covering with a shorter life that is easy to repair can suit a building you do not expect to keep. The decision is partly about your plans for the premises.
Single-ply membranes: EPDM, PVC and TPO
Single-ply membranes are factory-made sheets laid in one layer. EPDM is synthetic rubber, while PVC and TPO are plastic-based and are joined by hot-air welding. They are light, quick to lay and available with long manufacturer guarantees, which makes them popular on offices, schools and shop roofs.
Advantages
Few joints, low weight on the structure and a clean finish. The membrane is flexible, so it copes with small movement in the building. Repairs are practical, because patches can be welded or glued. Typical lifespans in the sources we use run from 20 to 30 years or more for EPDM, around 20 to 30 years for PVC and commonly 20 to 35 years for TPO, depending on the product.
Drawbacks
The details are the weak point. Corners, outlets and upstands are finished by hand on site, and a membrane can be punctured by dropped tools, sharp edges and careless foot traffic. Adhesives and solvents can also attack some membranes, and PVC needs to be kept clear of incompatible bitumen. On a busy roof, walkways become a necessity rather than an option.
Typical UK installed rates in that single source are £90 to £130 per m² for EPDM and £100 to £140 per m² for PVC or TPO, with a further £20 to £40 per m² where new insulation is needed. Individual products are described in our single-ply guide.
Built-up felt and mastic asphalt
Felt is the familiar layered bitumen roof, and asphalt is a hot-laid alternative, poured and spread in place. Both have long track records on commercial buildings across the country.
Advantages
The materials are widely understood, so repairs are easy to arrange, and a damaged patch can normally be cut away and replaced without stripping the roof. Good multi-layer felt systems are tough against foot traffic when they have a mineral cap sheet. Asphalt gives a continuous, slow-wearing surface that suits balconies, walkways and listed buildings that need a traditional finish.
Drawbacks
Felt ages as the bitumen dries and the surface cracks. Published lifespans vary by source: about 10 to 20 years, around 20, and up to 30 for a well-made system. One cost guide says a good felt job can last 20 years and a poor one fail in under 10, which tells you that the workmanship matters as much as the material. Torch-applied felt calls for hot-work precautions near combustible roofs and linings. Asphalt is heavy and needs specialist plant, and a small repair can cost more than its size suggests.
The same source puts torch-on felt at £80 to £120 per m². The layers and the fire precautions are set out in our felt roofing guide.
Profiled metal sheet and composite panels
Coated steel sheet is the workhorse of industrial roofing. It spans a long way between supports, goes up quickly and can carry rooflights built into the same profile.
Advantages
Its life is long when the coating is intact. One supplier quotes 15 to 25 years to first maintenance and over 40 years overall in typical environments, a cost guide says 40 to 70 years for metal roofs, and a trade body says over 50. Those figures disagree, and the fair reading is that the sheet outlasts the coating, so upkeep decides the outcome. The material is light and non-combustible in itself, and replacing individual sheets is possible.
Drawbacks
Rust starts where the protective coating is cut or scratched, and it spreads under the paint at the sheet edges, a problem covered in our guide to cut-edge corrosion. Fixings work loose with thermal movement, sealant at the laps dries out, and in condensing atmospheres a single skin can drip. Coastal and chemical sites shorten life, which is a reason to check the environment before specifying one. Old cement sheeting of similar profile may contain asbestos, so a sample is tested before any work disturbs it.
Where a sound metal roof is simply tired, an overlay can be the right answer, and our overlay guide lists what the old roof must offer.
Lead, zinc and copper
The sheet metals are the premium end of the choice. They cost more to lay and they ask for skilled labour, but they have the longest lives of any metal covering.
Lead
Sheet lead has long been the choice for flashings, valleys and parapet and box gutters. The figures we have are for correctly installed lead: flashings of over 80 years, over 100 for the higher codes, and lead flat roofs of 50 to 100 years. Sheet is sold by code, a thickness grade running from code 3 at 1.32 mm up to code 8 at 3.55 mm, with codes 5 to 8 used for gutters and valleys. Its drawback is theft risk, weight and a need for properly designed joints, drips and falls, because overlong pieces split as they expand and contract.
Zinc and copper
Zinc is reported at over 100 years in the manufacturer's data, with 60 years or so on severe industrial or marine sites, while a homebuilding source gives 60 to 100. Well-laid copper is reported to last at least 80 years. Both are formed into standing-seam sheets and both change appearance with weathering, which some owners like and others do not. Neither is cheap, and foot traffic marks both.
On pre-war commercial buildings in Bath, lead is often the hidden material that fails first. A cracked drip in a gutter can cost far more in damage to the ceiling than the lead ever cost to renew.
Slate, clay and concrete tile
Pitched commercial roofs use the same coverings as houses. Natural slate regularly lasts a century or more, with Welsh slate at the top of the range and Spanish at 75 to 100 years, although poorly fixed slate can fail within ten years whatever its quality. Clay plain tiles are quoted at 40 to 60 years by one source, while others put the minimum at 60 and note that old peg-tiled roofs have survived for centuries. Concrete tiles run from 30 to 50 years in one source and about 60 in another.
The pros are durability and appearance. Slate and clay look right on period buildings and weather gracefully. The cons are weight, which has to be checked against the roof structure, and the work involved in laying them. Fixings matter too. Iron nails rust long before the slate fails, which is why copper or similar non-ferrous nails are the sound choice, and why a slate roof that is losing slates in dry weather is probably suffering from nail failure and not weather.
In Bath's conservation area and on listed buildings, matched materials are often a condition of consent, which makes the choice for you. Natural stays natural, and a swap to a man-made slate is a visible change.
A side-by-side summary
The table sets out typical published lifespans and the main upkeep point for each material. Treat the ranges as typical, not guaranteed, and remember that exposure, drainage and workmanship move every one of them.
| Material | Typical life | Upkeep point |
|---|---|---|
| EPDM | 20 to 30 years or more | Check outlets, edges and seams |
| PVC and TPO | About 20 to 35 years | Keep clear of sharp edges and solvents |
| Built-up felt | 10 to 20 years, longer if well made | Watch for splits and lifted laps |
| Profiled steel | 15 to 25 years to first maintenance | Treat cut edges and reseal laps |
| Lead sheet | 50 to 100 years | Inspect drips, joints and gutters |
| Natural slate | 75 to 100 years or more | Check nails, lead and underlay |
Figures are drawn from GreenSpec, the Building Centre, a cost guide, a supplier and a trade body, and they do not always agree. Our guide to planned commercial roof maintenance explains how upkeep moves each of them towards the top of its range, and our page on commercial roof systems shows how these materials fit into complete build-ups.
If the material is already failing, the cause may be elsewhere. Our answer on why an industrial roof leaks goes through the usual culprits, several of which have nothing to do with the covering.
Turning the comparison into a decision
Once you have the options on paper, three questions usually narrow them. How long do you expect to occupy or own the building? How much will anyone walk on the roof? And what does the existing structure allow? A short horizon favours an economical covering that is easy to repair. Heavy foot traffic favours felt with a mineral cap, asphalt or a membrane with proper walkways. A light or weak structure rules out ballast and heavy tile.
We then check what the roof is made of today. Replacing a covering with something much heavier is a structural question, and a new covering that is 15 per cent or more heavier needs building control approval. Re-covering a smaller area, under 25 per cent of the envelope and under 50 per cent of the roof, normally does not. Your building control body can confirm either way.
A survey puts all of this on the record. We photograph your own roof, show you the layers under the covering and set the options out as a fixed price. If a repair will serve, the survey records that. Any work we carry out comes with a 10-year written workmanship guarantee. For planning, the commercial roofing page lists the full range of work we take on for businesses.