Dereham Roofers carries out commercial roofing in North Elmham and the surrounding area, covering flat roof replacement, profile metal sheeting, cladding, guttering and repairs on warehouses, industrial units, retail premises and office buildings.
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Commercial roofing is a different discipline from domestic work. The roof areas are larger, the materials are different, and the consequences of a leak or a structural failure are more serious, whether that means damaged stock, a wet trading floor or a health and safety issue for your staff. Getting the specification right from the outset is far more important than it is on a house.
We work on warehouses, agricultural and industrial units, retail and trade premises, and office buildings across North Elmham, Dereham and the wider Norfolk area. Jobs range from a patch repair on a leaking felt flat roof to a full re-sheet of a large profile metal roof. Every project starts with a proper look at what is actually there and what is causing the problem.
This is the angle most business owners do not get a straight answer on, so we will go through each system honestly. The right choice depends on your building, your budget and how long you plan to be in the property.
Traditional built-up felt consists of two or three layers of bitumen-impregnated felt bonded together with hot or cold bitumen. It has been used on commercial flat roofs in the UK for decades and is still widely fitted because the materials are readily available and most commercial roofers know how to lay them properly.
A well-laid three-layer built-up felt roof on a commercial building, with correct falls and adequate drainage, will typically last fifteen to twenty years before it needs attention. On larger, older roofs where the deck beneath has moved or settled, blistering and splitting are a common problem. When you see bubbles in the surface, that is usually moisture trapped during installation or water that has found its way under a lap joint.
Pros: Lower upfront cost than most alternatives. Familiar to most roofing contractors. Repairable with standard materials. Works well on large flat areas with simple geometry.
Cons: Shorter service life than EPDM or metal. More joints and laps than a single-ply system, so more potential failure points. Prone to blistering if laid in damp conditions or on a wet deck. Performance depends heavily on the quality of the laying, particularly at upstands, parapets and around penetrations such as rooflights and pipes.
EPDM (ethylene propylene diene monomer) is a single-ply rubber membrane supplied in large rolls. Because it can be fitted in very wide sheets with few joints, there are fewer places for water to get in. It is bonded to the roof deck with adhesive and taken up over upstands and parapets in a single continuous piece wherever possible.
EPDM is now a standard option on commercial flat roofs and is particularly well suited to roofs with rooflights, pipes or other penetrations that break up the surface, because the membrane can be dressed tightly around them. Manufacturer-quoted life expectancy for EPDM membranes is often stated at fifty years under test conditions, though real-world service life on a commercial building will depend heavily on the quality of installation and the condition of the deck beneath.
Pros: Fewer joints than built-up felt, so a lower risk of lap failures. Handles roof movement and thermal expansion well, because rubber is naturally flexible. Works in a wide temperature range. Does not require hot works, which matters on occupied premises or where a hot-works permit would be required. Lighter than some alternatives, which can matter if the roof structure has limited load capacity.
Cons: Higher material cost than standard felt. Requires careful preparation of the deck - any unevenness or contamination will show through and can affect adhesion. On very large roofs with complex geometry, experienced installers are essential because joins that are made incorrectly will fail. Not all roofers have experience with EPDM on larger commercial buildings.
Profile metal roofing, typically standing-seam steel or through-fixed steel or aluminium sheeting, is the standard covering on most modern industrial units, warehouses and agricultural buildings. It is durable, relatively lightweight and can span long distances between purlins without intermediate support.
The most common failure mode on profile metal roofs is not the sheet itself but the fixings and the sealant. Over time, the rubber washers on through-fixed screws compress and crack, and the sealant at ridges, eaves and gutter flashings breaks down. Water then tracks along the underside of the sheet before dropping, which is why the leak often appears well away from the actual entry point. A good inspection will identify whether the fixings are the issue or whether the sheets themselves have corroded through.
Where sheets are still structurally sound but the fixings are failing, an over-roofing system can be a cost-effective option: new purlins or rails are fixed to the existing structure and new sheets are laid over the top, avoiding the cost and disruption of stripping the old roof. Where the existing sheets are corroded or damaged, a full strip and re-sheet is the correct approach.
Pros: Long service life when correctly installed and maintained, typically forty years or more for a quality coated steel sheet. Fast to install on a simple rectangular structure. Good spanning capability reduces structural requirements. Can be insulated from above (warm roof) or below (cold roof), with warm roof construction being the better option for energy performance.
Cons: Condensation inside cold-roof metal buildings is a persistent problem if the existing vapour control layer and insulation are inadequate. Colour coatings fade over time and re-painting is not always practical. Through-fixed systems require ongoing maintenance of the fixings. Standing-seam systems are more expensive but require fewer penetrations through the sheet, which reduces the long-term maintenance burden.
Wall cladding on commercial and industrial buildings is often part of the same project as a roof replacement, because the same materials and the same fixing principles apply. Composite insulated panels, also called sandwich panels, are the most common cladding on modern commercial buildings. They combine an outer metal skin, an insulation core and an inner metal liner into a single factory-made unit.
Composite panels provide good thermal performance and a clean finished appearance, but older panels, particularly those with a polyurethane foam core, need to be assessed for fire performance before specification. This is relevant if you are re-cladding an older building. Panels with a mineral wool core do not carry the same concern.
Profiled steel cladding without an insulation core is also used where thermal performance is provided by a separate insulation system. On older agricultural and industrial buildings, corrugated steel or fibre cement sheets are still common and can be replaced on a like-for-like basis where the structure allows.
Not every job is a full replacement. A failing lap joint, a cracked upstand flashing, a blocked or broken gutter - these are all repairable without stripping the whole roof, provided the deck and the bulk of the covering are still sound. A common problem on commercial roofs is that a small repair is delayed, water gets into the deck, and what could have been a patch repair becomes a re-deck.
When asking a roofer to look at a potential repair, it is worth asking them to confirm the condition of the deck beneath the covering. On felt roofs, the deck is usually plywood, timber boarding or concrete. On metal roofs, the deck is the purlin and liner panel arrangement. If the deck is wet or damaged, a surface repair will not hold long term.
Repairs to single-ply membranes use compatible materials - you cannot patch EPDM with bitumen felt or vice versa, because they will not bond and will peel away. Always confirm that the repair material matches the existing system.
Commercial guttering is almost always in steel or aluminium rather than the UPVC you see on houses. The loads involved are much greater, particularly when autumn leaf fall or debris builds up over a large roof area. Box gutters, valley gutters and parapet gutters are common on commercial flat roofs and require regular clearance to prevent ponding and overflow.
A blocked or damaged gutter on a commercial building can cause water to back up under the roof covering at the eaves, which is a common source of leaks that look like a roof failure but are actually a drainage problem. Gutter outlets and downpipes should be part of any roof survey and any repair specification.
On larger buildings, internal drainage with flat-roof outlets and internal downpipes is often used. These outlets need to be kept clear and the sump areas around them need to be kept clean. If the sump area around a flat-roof outlet has cracked or the outlet flange has lifted away from the membrane, water will find its way through the deck before it reaches the outlet.
On commercial premises, the work needs to fit around your operations. On a warehouse, that might mean agreeing which bays are worked on first so you can keep stock in the unaffected area. On a retail or food premises, it may mean working outside trading hours to avoid noise and debris. These are straightforward practical conversations, but they need to happen at the quotation stage, not when the crew arrives on day one.
Access is the other key practical question. Scaffold, a mobile elevated work platform (MEWP) or a fixed access system on the building all have different cost implications and lead times. On a large roof, a MEWP is often the most practical approach. The choice of access method should be declared clearly in any quotation so you know what you are paying for.
Whether you are dealing with us or any other commercial roofer, there are questions worth asking before you commit to any work.
A detailed written quotation that answers these questions before you sign anything is a reasonable thing to expect and a sign that the contractor has thought the job through properly.
Commercial roofing costs vary considerably depending on the system, the size of the roof and the condition of the existing structure. As a general guide, built-up felt replacement on a commercial flat roof typically runs from around £25 to £45 per square metre for the covering alone, with EPDM membrane work generally ranging from £40 to £70 per square metre installed. Profile metal re-sheeting on a warehouse or industrial unit typically costs from around £20 to £50 per square metre for the sheets and fixing, depending on the profile specified and the complexity of the roof shape. These are indicative ranges only - any figure that applies to your building will come from a survey and a measured quotation.
Deck replacement, additional insulation, new guttering and access costs all add to the total. A quotation that seems significantly lower than others is worth querying: the most common reason is that it excludes deck repairs, access or waste disposal that the other quotes have included.
If you have a commercial roof in North Elmham or nearby that needs inspecting, repairing or replacing, call us to arrange a roof survey. Contact Dereham Roofers directly to book a visit.
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Call any time. Calls are answered day and night and passed straight to our roofers.
