Dereham Roofers provides commercial roofing in Gressenhall and the surrounding area, covering warehouses, industrial units, retail premises and office buildings from flat roof replacement to profile metal sheeting.
Commercial roofing is a different discipline to domestic work. The spans are larger, the consequences of a leak are more serious, and the materials used on most commercial buildings are nothing like those on a standard house. At Dereham Roofers we carry out the full range of commercial roofing work across Gressenhall and the wider Norfolk area, including flat roof replacement, profile metal sheeting, single-ply membranes, EPDM rubber systems, cladding and guttering. We plan work around your operating hours so that disruption to your business is kept to a minimum.
Every commercial roofing job starts with a proper survey. That means getting up on the roof, not just looking at it from the ground. A visual inspection from below might reveal a stain on the ceiling, but it will not tell you whether the deck is saturated, whether the upstands have failed, or whether the drainage outlets are partially blocked and pooling water for weeks at a time. Those details change both the scope of work and the materials chosen.
This is the angle that commercial property owners and facilities managers need to understand clearly, because a commercial roof can be failing for months before the signs become obvious inside the building. By the time water appears on a ceiling, the damage has usually been happening much longer than it looks. Catching the early warning signs saves money and avoids the disruption of emergency repairs.
Staining on ceiling tiles or plasterboard is the most obvious sign, but far from the earliest. Damp patches that appear after heavy rain and then dry out are often dismissed as condensation. They are not always condensation. If a patch reappears in the same location after successive wet spells, that is a leak finding a consistent path through the roof build-up, even if the entry point is some distance away.
Bubbling or flaking paint on internal walls near roofline height is another indicator. So is a persistent musty smell in an area of the building that is otherwise ventilated normally. Mould growth on internal surfaces, particularly in corner junctions near eaves or parapet walls, points to moisture entering the fabric of the structure.
If you notice that insulation above a suspended ceiling is wet or discoloured when you lift a tile to change a light fitting, that is a sign that water has been tracking through the roof for some time. Saturated insulation loses most of its thermal value and, once wet, rarely dries out fully without being replaced.
On a flat felt roof, blistering and cracking are clear signs that the membrane is breaking down. Blisters form when moisture trapped beneath the felt turns to vapour in warm weather and pushes up the surface layer. Those blisters eventually crack, giving rainwater a direct path into the roof build-up. A cracked or blistered felt roof that has not been attended to will deteriorate quickly once water gets beneath the surface.
On a single-ply or EPDM rubber roof, look for lifting at the edges, particularly around upstands, parapet flashings and where the membrane meets a wall or kerb. Adhesion failure at these joints is one of the most common points of entry for water on flat commercial roofs. The field of the membrane may look fine while the perimeter is already allowing water ingress.
Profile metal roofing on commercial and industrial buildings develops its own set of problems. Fixings corrode over time, particularly in exposed positions, and corroded fixings allow sheets to lift slightly in high winds, which then lets wind-driven rain work its way underneath. Lap sealants between sheets dry out and crack with age and UV exposure. Ridge and eaves cappings work loose. Any of these faults, individually, might seem minor. Together they add up to significant water ingress during a Norfolk winter.
Gutters and downpipes on commercial buildings carry a much greater volume of water than residential ones. Blocked or overflowing gutters on a large commercial roof can deposit water against fascia boards, behind flashings and into wall cavities in quantities that cause rapid damage. Visible overflow marks on the outside of a building, or plant growth in gutters visible from ground level, are warnings that the drainage system needs attention before the next period of sustained rain.
Parapet walls and the flashings that seal the junction between a flat roof and the parapet are a consistent weak point. The flashing, whether lead, zinc or a metal-faced strip, expands and contracts with temperature changes. Over years, this movement works the flashing loose from the mortar joint or the adhesive fixing that holds it to the upstand. Once the flashing lifts even a few millimetres, water runs straight down behind it and into the roof edge. This is often the actual source of a leak that appears, internally, to be coming from somewhere much further into the building.
Age is the most straightforward cause. A built-up felt roof has a typical service life of around 15 to 25 years depending on the number of layers, the quality of the original installation and how well it has been maintained. An EPDM rubber membrane, correctly installed and with properly bonded seams, can last considerably longer. Profile metal roofing, depending on the coating and gauge, is often rated for 25 to 40 years, but fixings and sealants will need attention well before the sheets themselves fail.
Poor original installation is a significant factor in early roof failure. Problems include insufficient falls on a flat roof (which leads to ponding water), inadequate upstand heights at walls and kerbs, poorly bonded laps on felt or single-ply systems, and fixings installed without the correct spacing or torque for the sheet profile being used. A roof that was not installed correctly will fail earlier than the material's rated life suggests, and it will often fail in multiple places at once.
Lack of maintenance accelerates the deterioration of any roofing system. Blocked outlets cause standing water, which exerts continuous pressure on the membrane and promotes algae and moss growth that further degrades the surface. Debris accumulation in gutters and valleys traps moisture against vulnerable junctions. Small splits or lifted flashings that could be fixed in an hour if caught early become major repair jobs after a winter of water ingress.
Thermal movement is a constant mechanical stress on any commercial roof. Large flat roofs expand and contract significantly between summer and winter temperatures. If the roof build-up, particularly the membrane and its insulation board, is not specified to accommodate this movement, cracking and delamination follow over time. This is one reason why the specification matters as much as the installation.
Foot traffic is another cause that is often overlooked. Service engineers accessing rooftop plant, HVAC units or communications equipment can damage membrane surfaces if no walkway protection is in place. Point loads from foot traffic puncture or crease thin membranes and dislodge laps. If your roof has regular maintenance access, walkway pads or protection boards should be part of the roof's design.
When a flat roof has reached the end of its serviceable life or when repairs are no longer cost-effective, full replacement is the right course of action. On a commercial building this typically means stripping back to the structural deck, inspecting the deck for rot or damage, laying new insulation to meet current standards, and applying the chosen membrane system.
EPDM rubber and torch-on felt are two widely used systems on commercial flat roofs. EPDM is a single-ply rubber membrane that is bonded to the insulation substrate and lapped and sealed at all joints. It handles thermal movement well, is resistant to UV degradation, and is a proven commercial roofing material. Torch-on felt, applied in multiple layers with each layer heat-bonded to the one below, is the more traditional approach and remains a reliable choice where budget is a primary consideration.
Commercial flat roof replacement costs in Norfolk typically range from around £70 to £130 per square metre for a standard torch-on felt system, rising to £90 to £160 per square metre for EPDM, depending on deck condition, insulation specification, access requirements and detailing complexity. These are indicative figures and the actual cost depends on the specific building and scope of work.
Industrial units, warehouses and agricultural buildings across Norfolk are commonly roofed and clad with profile metal sheeting, typically steel with a polyester or plastisol coating. This is an efficient and cost-effective system for large span commercial buildings, but it requires proper installation and periodic maintenance to perform over its intended service life.
We carry out new metal roof and cladding installations as well as over-roofing of existing profiles. Over-roofing, where a new metal sheet is laid directly over the existing one with a new layer of insulation between, avoids the cost and disruption of stripping the old roof and disposing of the waste, and can significantly improve the thermal performance of an older industrial building.
Repair work on metal roofs includes replacing corroded or damaged sheets, re-fixing lifted sheets, replacing corroded fixings with correctly specified alternatives, resealing sheet laps, and replacing failed ridge, eaves and barge cappings. Localised repairs of this type can extend the life of a metal roof by many years if the main sheet material is still structurally sound.
Guttering on commercial and industrial buildings handles a very large volume of rainwater from extensive roof areas. Box gutters, ogee cast iron gutters on older buildings, deep-flow uPVC systems and pressed steel or aluminium valley gutters are all common across commercial premises in this area.
Common problems include blocked outlets and downpipes, failed joints between gutter sections, corrosion on steel and cast iron systems, and gutters that have dropped out of fall so that water pools and eventually overflows rather than draining away. Any of these faults can direct large quantities of water against the building fabric.
Box gutters, which are built into the roof structure between spans on older industrial buildings, are a particular concern. When the waterproofing lining of a box gutter fails, water has nowhere to go except into the building. Relining a box gutter with a bonded membrane system is a much more cost-effective solution than replacing the entire gutter structure.
Routine gutter clearing is maintenance, not a repair job, but it is maintenance that protects everything below it. A full commercial gutter clear should include checking outlet grates and downpipe tops for blockages, flushing downpipes to confirm they are flowing freely, and checking gutter fixings and joints while access is in place.
A commercial roofing project on an occupied building needs careful scheduling. Early starts, weekend working, or phasing the work in sections so that only part of the building is under active work at any one time are all options that can be discussed when a project is being planned. The aim is to carry out the roofing work without forcing you to shut down or relocate operations.
For larger projects, a clear programme of works helps everyone plan around the disruption. Knowing in advance which areas will be under active work on which days allows you to manage your staff and protect stock or equipment that could be affected if weather intervenes during the work.
Before committing to any commercial roofing contractor, there are a few questions that will help you make a sound decision.
A written quotation with a clear specification gives you a basis for comparison and avoids misunderstandings about what is and is not included in the price.
If you have noticed any of the warning signs described above, or if your commercial roof is approaching or past its expected service life, the right first step is a proper survey carried out from the roof itself. Contact Dereham Roofers to arrange a roof survey for your commercial premises in Gressenhall or the surrounding area. We will give you a clear, written assessment of what we find and a straightforward quotation for any work that is needed.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
