Downham Market Roofers provides commercial roofing in March, covering warehouses, farm buildings, retail units and offices with practical, specification-led solutions.
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When a commercial roof fails, it rarely fails quietly. A leaking warehouse can halt operations, damage stock and trigger disputes with tenants or insurers. A deteriorating farm building roof can compromise stored machinery or feed. Getting the specification right from the outset matters more on a commercial building than almost anywhere else, because the cost of getting it wrong compounds quickly.
We work on commercial and industrial properties across March and the surrounding Fenland area, including warehouses, retail premises, office buildings, agricultural units and light industrial sheds. This page focuses on what that actually involves: the materials available, their honest pros and cons, what they cost in broad terms, and what questions you should be asking before any work starts.
Commercial roofing is not simply a scaled-up version of domestic work. The buildings are bigger, the roof areas are often flat or very low-pitch, the structural loads are different, and the consequences of failure are greater. A good commercial roofer will survey the existing structure, understand how the building is used, and specify a system that suits the loading, drainage, access requirements and expected lifespan.
The main categories of work are: full re-roofing (stripping and replacing the existing covering), overlay systems (applying a new membrane over the existing one where the deck is sound), repair and maintenance, and new-build roofing on extensions or new structures. Each calls for a different approach and a different material specification.
Many commercial buildings have either a flat or very low-pitched roof, or a large expanse of profiled metal sheeting at a shallow pitch. The material you choose will affect upfront cost, maintenance requirements, lifespan and how the roof performs over time. Here is an honest run-through of the main options.
Traditional built-up felt roofing uses multiple layers of bitumen-based felt bonded together, either by torch-on application or with cold adhesive. It has been used on commercial flat roofs for decades and remains one of the most widely understood systems among both roofers and surveyors.
Pros: Lower upfront material cost than most alternatives. Widely available. Straightforward to repair. A three-layer torch-on system on a sound deck will typically last 15 to 20 years before it needs attention.
Cons: Requires skilled application; poor torch-on work is a common cause of early failure. The laps between felt sheets are the weak point and need checking during any inspection. Not suitable where the roof deck is in poor condition or where ponding water is a persistent problem. Torch-on work carries fire risk on occupied buildings and may require precautions around combustible insulation or roof structures.
Typical cost for a commercial torch-on felt re-roof: roughly £40 to £70 per square metre, depending on the number of layers, insulation specification and access requirements. Larger flat roofs tend to come in at the lower end of that range per square metre.
EPDM (ethylene propylene diene monomer) is a single-ply rubber membrane that has become increasingly common on commercial flat roofs over the past fifteen years. It is available in large sheets that can cover substantial roof areas with very few seams, which significantly reduces the risk of lap failures.
Pros: Excellent weather resistance and flexibility in cold temperatures. The low number of joints is a genuine advantage on a large commercial roof. Material lifespan of 25 to 40 years is achievable with reasonable maintenance. Lightweight, which matters on older structures with marginal load capacity. Not susceptible to UV degradation in the way that some bitumen products can be.
Cons: Higher material cost than felt. Requires correct surface preparation and bonding; adhesive failures at the perimeter are the most common cause of problems on poorly installed systems. Punctures from foot traffic or falling debris need prompt repair to prevent water ingress. Not all roofers have experience installing it correctly on larger commercial spans.
Typical cost for EPDM on a commercial flat roof: roughly £60 to £90 per square metre installed, including insulation board where required. The higher upfront cost is often offset by a longer maintenance-free period.
TPO (thermoplastic polyolefin) and PVC single-ply membranes are heat-welded at the seams rather than glued or torched. The welded seam is genuinely strong when done correctly and is one of the most reliable joint methods available in flat roofing.
Pros: Strong, consistent seams when hot-air welded by a trained installer. Available in light colours that reduce heat absorption inside the building. Suitable for large uninterrupted roof areas. TPO in particular is resistant to oils and greases, which is worth considering on agricultural or light industrial buildings.
Cons: The quality of installation depends heavily on the operator's skill and equipment. A poorly welded seam is worse than a well-bonded felt lap, not better. PVC can become brittle over time in very cold conditions if a lower-grade product is used. These systems generally require a competent contractor with the correct hot-air welding equipment, not all roofers carry this.
Typical cost for single-ply TPO or PVC on a commercial flat roof: roughly £65 to £100 per square metre installed, depending on specification and access. Mechanically fixed systems at the lower end, fully adhered systems at the higher end.
Profiled steel or aluminium sheeting is widely used on warehouses, agricultural buildings, portal frame units and many light industrial premises. It is fast to install on large structures and, when properly specified, very durable.
Pros: Spans large areas quickly. Available in insulated composite panel form (two skins of metal with rigid insulation bonded between them), which provides good thermal performance. Repair is straightforward on localised damage. Galvanised and plastisol-coated steel carries a manufacturer's finish guarantee of 15 to 25 years in most cases, though actual sheet lifespan is considerably longer.
Cons: Exposed fasteners (through-fixed systems) are the most common source of leaks on older agricultural and industrial roofs. The rubber washer under each fastener degrades over time and allows water ingress. Condensation is a significant problem on uninsulated or single-skin metal roofs, and it is frequently misdiagnosed as a leak from outside. Older asbestos cement roofing sheets require specialist removal before re-roofing and that cost needs to be factored into any budget.
Typical cost for new profiled steel re-roofing on an agricultural or industrial building: roughly £25 to £50 per square metre for through-fixed steel sheets, rising to £60 to £90 per square metre for composite insulated panels. Asbestos removal, where required, is costed separately and depends on the quantity and condition of the sheets.
Not all commercial buildings have flat or metal roofs. Office conversions, retail premises and some farm buildings carry pitched roofs finished in slate, concrete tile or clay tile. The principles are similar to domestic pitched roofing but the scale and access requirements are different.
Natural slate is the most durable pitched roofing material available. A well-laid natural slate roof on a sound timber structure can last 80 to 100 years or more. The upfront cost is higher than concrete tile, typically £80 to £130 per square metre for a full re-roof, but the long-term maintenance costs are lower if the slates themselves are sound.
Concrete interlocking tiles are more common on newer commercial buildings and agricultural conversions. They are faster to lay, lower in cost (typically £50 to £80 per square metre for re-roofing) and offer reasonable durability, though the surface coating can erode over 30 to 40 years, leading to moss growth and eventually to freeze-thaw damage of the tile surface.
Fibre cement slates are a middle option: lower cost than natural slate but a better appearance than concrete tile on a prominent building. Typical re-roofing cost is roughly £60 to £90 per square metre installed.
A proper inspection before any commercial roof work is not optional; it is where the correct specification starts. A survey should establish the condition of the existing deck, the thickness and type of any insulation already in place, how the roof drains and whether the outlets and gutters are adequate, and whether there are any structural issues that need addressing before a new covering goes on.
On older flat roofs, moisture in the existing insulation is a common problem that is easy to miss visually. Moisture in the deck significantly shortens the life of any new membrane laid over it, so knowing whether it is present before you specify affects which approach you take: strip and replace, or overlay.
An inspection should also identify any penetrations through the roof, such as pipework, rooflights or plant equipment, because these are among the most common sites for water ingress on commercial flat roofs. Detailing around penetrations requires care and should always be checked as part of any new installation or repair.
One of the most common questions on a commercial roof is whether to repair what is there or replace it entirely. The honest answer depends on the age of the existing system, the extent of the damage, and whether the underlying deck is sound.
If the existing membrane or sheeting is nearing the end of its expected life, repairing a failing section often buys only two or three years before another section fails. In that situation, full replacement is usually better value. If the roof is mid-life and the damage is genuinely localised, a well-executed repair can extend the roof's useful life significantly at a fraction of replacement cost.
The risk with patch repairs on older commercial flat roofs is that they can mask underlying moisture that is already spreading through the insulation. A contractor who recommends repair without looking at the deck condition is not giving you the full picture.
On an occupied commercial building, the roofing programme needs to be planned around the business using the space below. That means thinking about access routes for materials and plant, temporary weatherproofing if sections of the roof are left open at the end of a working day, dust and noise below, and the sequence of work on roofs with multiple sections or bays.
On a warehouse or farm building that is storing stock, vehicles or machinery, physical protection of the contents is part of the job, not an afterthought. Ask any contractor you speak to how they manage this specifically, not just in general terms.
Agricultural, industrial and retail buildings often share similar construction types, and the material options we discuss here apply to many of them.
If you have a commercial or industrial roof that needs inspection, repair or replacement in or near March, call us to arrange a roof survey. We will assess what is there, explain the options honestly, and give you a clear written quotation for the work.
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Call any time. Calls are answered day and night and passed straight to our roofers.
