Newmarket Roofers provides commercial roofing services in Bury St Edmunds, covering flat roof replacements, repairs, re-covering, leadwork and guttering on retail units, warehouses, offices and agricultural buildings.
One of the most important decisions you will make when replacing or re-roofing a commercial building is which material to use. The choice affects upfront cost, how long the roof will last, how much maintenance it will need, and whether it suits the building's structure and use. There is no single best answer - each material has genuine strengths and genuine drawbacks, and the right choice depends on your specific building and budget.
Below is an honest breakdown of the main options used on commercial roofs, including typical costs and the things most roofing companies do not mention upfront.
Torch-on felt, also called modified bitumen or built-up felt, has been the standard for flat commercial roofs in the UK for decades. It is applied in layers using a gas torch to heat and bond each sheet, creating a waterproof membrane over the deck.
Pros: Widely available, well understood by most roofers, relatively quick to install, and cost-effective for large roof areas. A properly specified two-layer or three-layer system handles the demands of a commercial flat roof well. Typical installed costs for a full flat roof replacement in felt run from around £40 to £70 per square metre, depending on the number of layers and the condition of the existing deck.
Cons: A single-layer torch-on system, sometimes offered at lower prices, does not perform as well as a multi-layer build-up and has a shorter service life. Felt roofs also need the deck to be sound and dry before installation - applying new felt over a damp or deteriorated deck is false economy. Lifespan is typically 15 to 25 years for a properly installed system, less for budget single-layer work.
Felt is still a solid choice for large, straightforward commercial flat roofs where budget is the primary consideration and the building owner understands the maintenance commitment.
EPDM (ethylene propylene diene monomer) is a single-ply rubber membrane increasingly used on commercial flat roofs. It comes in large sheets that can often cover a roof in one or two pieces, eliminating the lap joints that are a common failure point in felt systems.
Pros: EPDM is flexible and handles temperature movement well without cracking. It is resistant to UV degradation, which is one of the main reasons felt surfaces deteriorate. A correctly installed EPDM roof typically lasts 25 to 35 years or more. Installed costs for EPDM on a commercial roof generally run from around £50 to £80 per square metre, depending on roof size and detailing complexity.
Cons: EPDM is not as widely installed as felt, so fewer roofers have genuine experience with it. Detailing around penetrations, outlets and upstands requires care - poor detailing at these points is where EPDM roofs most often fail. It is also not suited to roofs that will be used as walkways or where there is regular foot traffic, as it is not designed as a walking surface without additional protection.
EPDM is worth considering seriously for commercial buildings where a longer interval between replacements is a priority, particularly if the building is in active use and disruption from future roofing work would be costly.
TPO (thermoplastic polyolefin) and PVC (polyvinyl chloride) single-ply membranes are heat-welded at the seams, creating a fully bonded joint that is often stronger than the membrane itself. They are commonly specified on larger commercial and industrial roofs.
Pros: Hot-welded seams are a significant advantage over adhesive laps. Both TPO and PVC membranes are available in light colours, which reduces heat absorption on large flat roofs. They can be mechanically fixed, adhered or ballasted depending on the roof structure and wind loading requirements. Installed costs typically range from around £60 to £100 per square metre for commercial applications.
Cons: The materials and installation require specialist equipment. TPO and PVC are more expensive than felt or EPDM, though the longer expected service life (often 25 to 40 years for a quality system) can justify the cost over the building's lifetime. PVC can become brittle over time in sustained low temperatures.
Profiled metal sheeting - typically steel or aluminium - is the standard roof covering for industrial units, agricultural buildings, warehouses and many modern commercial structures. It is also used as standing seam metal roofing on more architecturally prominent commercial buildings.
Pros: Profiled steel sheeting covers large areas quickly and is lightweight relative to other materials. It is durable when the coating is intact, with lifespan typically quoted at 25 to 40 years depending on the coating specification. Standing seam zinc or aluminium roofing has a significantly longer lifespan and requires minimal maintenance.
Cons: Profiled steel sheeting relies on its coating for corrosion resistance. Once the coating fails - through mechanical damage, cut edges rusting, or age - the sheets can corrode rapidly. Older steel sheet roofs on agricultural and industrial buildings often have corroded sheets, failing sealants at laps and corroded fixings. These can often be over-sheeted rather than stripped, which reduces cost and disruption. Condensation on the underside of uninsulated steel sheets is also a common problem in buildings where the internal temperature and humidity vary.
Pitched roofs on older commercial buildings often use natural slate or clay and concrete tiles. These are durable materials when the supporting structure is sound and the flashings are maintained.
Pros: Natural slate, properly laid, can last 80 to 100 years or more. Clay tiles have similar longevity. Both suit the character of older commercial buildings and are appropriate where planning or conservation requirements apply.
Cons: The cost of new natural slate and the skill required to lay it correctly make it significantly more expensive than artificial alternatives. Artificial slates (fibre cement) are a common alternative at lower cost, though their lifespan is shorter - typically 25 to 40 years. On commercial pitched roofs, the weak points are usually the flashings and leadwork at abutments and valleys rather than the slates or tiles themselves.
Lead remains the material of choice for flashings, valleys, soakers and parapet details on both flat and pitched commercial roofs. Properly specified and installed lead, at the correct code weight for the application, outlasts virtually every other flashing material. Code 4 lead is the minimum for most flashing applications; code 5 or 6 is appropriate for wider flashings and valley work.
Lead that has been applied too thin, in excessively long runs without expansion joints, or that has not been properly dressed back into joints, will fail early through fatigue cracking. This is a detail worth checking on any commercial roof survey.
The guttering system is part of the roof, not an afterthought. On large commercial roofs, box gutters, valley gutters and internal drainage outlets all need to be designed to handle the volume of water the roof area will produce in heavy rain. Undersized outlets, poorly falling gutters, and silt-blocked drainage are among the most avoidable causes of commercial roof water damage.
When a flat roof is being replaced, it is worth reviewing the drainage at the same time. If outlets are undersized for the roof area, or if the falls in the gutter are inadequate, the problem will not be solved by a new membrane alone.
If you are considering a flat roof replacement, re-cover or repair on a commercial property in or near Bury St Edmunds, call Newmarket Roofers to arrange a survey. We will look at your building, give you a clear picture of what is there and what the options are, and let you make an informed decision without being pushed towards the most expensive solution.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
