Thetford Roofers provides commercial roofing installations, repairs and full refurbishments for business premises and industrial units in Feltwell and the surrounding area.
Call any time. Calls are answered day and night and passed straight to our roofers.
We carry out commercial roofing work for premises in Feltwell and the surrounding area. The work covers new roof installations, repairs to failing sections, re-covering of flat roofs, and full replacement of commercial pitched roof sheeting.
Every job starts with a proper survey of what is already there. The material you choose for a new or replacement roof affects how long it lasts, how much maintenance it needs and what it costs both upfront and over time. This page sets out the main options honestly, including where each one works well and where it has limitations.
Many commercial buildings have flat or low-pitch roofs over single-storey extensions, plant rooms, warehouses or workshop spaces. The two systems we use most on commercial flat roofs are built-up felt and EPDM rubber membrane. Here is an honest comparison of both.
Built-up felt uses two or three layers of reinforced bitumen felt, bonded to one another using a gas torch. It has been used on commercial buildings for decades and is widely understood by roofers and surveyors alike. A good quality torch-on felt installation on a commercial flat roof typically costs in the region of £40 to £65 per square metre.
Where it works well: Straightforward rectangular roofs with standard detailing. Cost-effective for large areas. Easy to repair locally if a section fails before the whole roof needs replacing.
Where it has limitations: Bitumen degrades when exposed to UV over many years, and the mineral surface layer that protects the top sheet does wear down. A felt flat roof on a commercial building has an expected service life of roughly 15 to 25 years, depending on specification, detailing quality and how the roof is maintained. Felt is also more vulnerable to foot traffic damage than some alternatives. Any regular access to the roof for plant maintenance increases the risk of punctures and abrasion.
EPDM (ethylene propylene diene monomer) is a synthetic rubber sheet membrane applied in large pieces, cold-bonded to the deck and to itself at seams. Because the sheets are large, there are far fewer seams than in a felt system, which reduces the number of potential failure points. EPDM on a commercial flat roof typically costs in the region of £60 to £90 per square metre installed.
Where it works well: Roofs with complicated shapes, penetrations, rooflights or plant equipment that creates a lot of detailing work. EPDM bonds well around upstands and outlets. It performs well through frost and is not degraded by UV in the way bitumen felt is. A quality EPDM installation has an expected service life of 30 years or more under normal conditions.
Where it has limitations: EPDM is more expensive per square metre than felt. Repairs, while straightforward with the correct materials, are less familiar to roofers who do not regularly work with rubber membranes - so if you ever need a patch repair, make sure the contractor knows the system. It is also important that the cold adhesive cure is managed correctly in cold weather; work should not proceed in temperatures below 5 degrees Celsius without specific cold-cure adhesives.
Liquid coatings are sometimes marketed as a quick solution for ageing flat roofs. They are brushed or rolled onto the existing surface and cure to form a waterproof layer. They can be a cost-effective solution for extending the life of a sound existing membrane that has surface cracking but no underlying deck damage. They are not a substitute for a full re-cover where the membrane has failed or the deck is wet. A liquid coating applied over a failing membrane will eventually follow the membrane down. Ask specifically whether the substrate has been assessed before a liquid coating is proposed.
Industrial units, agricultural buildings and some commercial premises use pitched roofs clad in profiled sheeting. The main materials are fibre cement and metal.
Fibre cement profiled sheets are durable and non-combustible, which matters for certain building uses. They are heavier than metal sheets and require a closer-spaced purlin structure to support them. A common problem with older fibre cement roofs is that sheets become brittle over time and can crack if walked on without proper access boards. Repairs to individual sheets are straightforward; however, sourcing matching profiles on very old roofs can be difficult. Re-sheeting a commercial pitched roof in fibre cement typically costs from £25 to £50 per square metre for the sheet material and fixing, not including any structural work to the purlins.
Metal sheet roofing is lighter than fibre cement and can span wider purlin spacings. Modern coated steel sheets have factory-applied colour finishes that resist corrosion for many years. The main failure modes on older metal sheet roofs are corrosion at fixings (where the washer seal has failed and allowed water in around the screw), fatigue cracking at the crown of profiles after many years of thermal movement, and failed mastic at overlaps. Re-sheeting in metal typically costs from £30 to £60 per square metre installed, depending on profile, material thickness and the amount of detailing involved at eaves, ridges and verges.
Metal roofs can also be over-clad rather than stripped and replaced. Over-cladding places new sheets over the existing ones, avoiding the cost and disruption of stripping. This only makes sense if the existing structure can take the additional load and the existing sheets are not so degraded that they cannot support foot traffic safely during the over-cladding process. A structural check is sensible before committing to over-cladding.
Building regulations require certain thermal performance from commercial roofs, and any refurbishment work is an opportunity to improve insulation if it is currently below current standards. On flat roofs, rigid insulation boards are fitted above the deck (warm roof construction) or below it (cold roof construction). Warm roof construction is generally preferred for commercial buildings as it keeps the deck warm and dry, reducing the risk of condensation within the roof structure. Adding 100mm of rigid insulation to a commercial flat roof refurbishment typically adds in the region of £10 to £20 per square metre to the material cost, depending on insulation specification.
The material choice for the main field of the roof matters, but flashing and drainage detailing is where many commercial roofs fail first. Lead flashings are the traditional choice at parapets, upstands and rooflights and remain one of the most durable options when correctly dressed. Aluminium and proprietary metal flashings are lighter and easier to work with on large commercial roofs. Whatever material is used, flashings must be mechanically fixed and sealed, not simply relied on by gravity or mortar alone.
Commercial flat roof outlets need to be sized correctly for the roof area they drain. Undersized or blocked outlets cause ponding, which accelerates membrane breakdown. The standard guidance is a minimum of one outlet per 50 square metres of roof area, with additional emergency overflow provision at parapet walls to prevent water building up if an outlet blocks. Ask your roofer whether the outlet specification on your building meets that standard.
A commercial flat roof inspected and maintained annually - outlets cleared, flashings checked, any surface splits sealed - will consistently outlast the same roof left without attention. The cost of an annual inspection and minor maintenance is very small compared with the cost of repairing water damage to a building's interior or replacing a roof prematurely. On EPDM and felt roofs, small splits or lifting edges at flashings can be sealed quickly if caught early; left over a winter they allow water to saturate the deck and may make a full replacement necessary.
If you have a commercial roof in or near Feltwell that needs surveying, repairing or replacing, call Thetford Roofers. We will assess what is there, explain the options that suit your building and your budget, and give you a price before any work starts.
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Call any time. Calls are answered day and night and passed straight to our roofers.
