Dereham Roofers provides commercial roofing for businesses, landlords and industrial premises in Horsford and the surrounding area, covering flat roofs, pitched roofs, cladding systems and guttering on every type of commercial building.
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Commercial roofing is a different discipline to domestic work. The roof areas are larger, the consequences of a leak are more serious, and the materials and methods used differ from those on a typical house. A leak into a retail unit, warehouse or agricultural building can damage stock, equipment or the structure itself, and it can stop your business trading.
The work covers a wide range, from full roof replacements on large flat-roofed warehouses to repairs on a small barn or retail unit, from new box-profile cladding systems to guttering maintenance on a block of commercial premises. Getting the specification right from the start is what separates a roof that lasts from one that fails inside a few years.
Flat roofs are the most common roof type on commercial buildings. Older systems used built-up felt, which typically lasts 15 to 25 years before it needs replacing. Modern alternatives include EPDM rubber membrane, which handles ponding water, temperature cycling and UV exposure well and is a sensible choice for most commercial flat roof replacements. Single-ply membranes are another option on larger commercial structures where sheet sizes and speed of installation matter.
Pitched roofs on commercial buildings, including agricultural barns, industrial units and older retail properties, are usually clad in profiled steel or fibre cement sheeting. These systems can be repaired or fully re-clad, and modern insulated panels give a significant improvement in thermal performance over older single-skin sheets.
Cladding systems do more than keep the rain out. Wall cladding on industrial and agricultural buildings protects the steel frame and insulation beneath. When panels corrode, delaminate or are damaged by impact, water can track behind the outer skin and cause structural rust that is expensive to repair. Catching cladding problems early is far cheaper than leaving them.
Guttering on commercial premises takes more water off a larger roof area than a domestic system. Cast iron, aluminium and UPVC are all used, and the right choice depends on the building type, the roof area and the budget. Blocked or broken commercial gutters can cause water to run down external walls, leading to damp penetration and masonry damage.
Flat roofs fail at seams, upstands and penetrations first. The field of the membrane often remains sound while the detail work at edges, drainage outlets and roof-light kerbs lets water in. A common problem is inadequate falls, meaning water sits rather than drains, accelerating membrane degradation and increasing the risk of structural loading.
Profiled metal roofing is vulnerable at the laps between sheets and around fixings. Older steel fasteners corrode and the rubber washers beneath them harden and crack, allowing water to track down through the fixing hole. Re-fixing with modern stitching screws and sealing laps is often enough to give a failing metal roof several more years of service before a full replacement is needed.
Box-profile and standing-seam roofs on agricultural and industrial buildings develop moss and lichen growth that holds moisture against the sheet surface, accelerating surface corrosion. Cleaning and treating the surface, followed by a protective coating, can extend the roof life significantly.
Guttering on large commercial buildings is often neglected until it fails visibly. Sagging aluminium sections, cracked joints and blocked downpipes are all found regularly. On a building with a large flat roof, a blocked outlet can cause ponding deep enough to exceed the structural load the roof was designed to carry.
Before any commercial roofing work is priced, a thorough survey is essential. A good surveyor will check the membrane or sheet covering, all upstands and flashings, every penetration through the roof surface, the drainage outlets and gutters, and the condition of the supporting structure where it can be accessed. They should tell you not just what is wrong but why it has failed, so the repair addresses the cause rather than the symptom.
If you are a landlord or a business owner with a lease, it is worth checking your schedule of dilapidations or lease obligations before the survey. Roofing works can be a significant liability, and knowing what you are responsible for before a survey shapes the scope of work. Ask the surveyor to separate what needs doing now from what can wait, with an honest assessment of how long you have before deferred items become urgent.
For any commercial job, insist on a written specification before you agree to a price. This should name the system being installed, the manufacturer and grade of materials, how existing material is to be stripped or prepared, and how drainage, details and flashings will be treated. Without a written spec, comparing quotes from different contractors is almost impossible.
This is the section most business owners and landlords want to read first, and understandably so. Commercial roofing costs vary considerably, and the range is wide enough that a figure without context is almost meaningless. What follows is a realistic breakdown of the factors that push costs up or down, so you can sense-check any quote you receive.
For a straightforward flat roof replacement using EPDM rubber membrane on a clean, structurally sound deck, typical costs in Norfolk currently fall in the range of £50 to £90 per square metre for the complete installation, including stripping the old felt, preparing the deck, installing the new membrane and dressing all upstands and outlets. The lower end of that range applies to simple, regular shapes with good access. The upper end applies where the roof has multiple penetrations, complex detailing or where the deck needs repair or upgrading.
If you are replacing like-for-like felt with a torch-on or cold-applied felt system rather than upgrading to EPDM, costs are broadly similar, though the long-term performance and maintenance burden differ. Modern felt systems are more reliable than the old three-layer built-up felt that is still found on many commercial buildings.
Re-cladding a pitched agricultural or industrial roof with new profiled steel sheeting typically costs £30 to £70 per square metre for the sheet covering alone, before guttering, flashings or structural work. Insulated composite panels, which provide a finished inner lining and significantly better thermal performance, run from around £60 to £120 per square metre installed. These are wide ranges because panel thickness, sheet profile, colour finish and roof pitch all affect the price.
Repairs to existing metal roofing are harder to price without seeing the roof. Re-fixing loose sheets and replacing corroded fixings on a modestly sized barn might cost a few hundred pounds. Sealing and coating a 500 square metre roof in poor condition could run to several thousand.
Access is the single biggest variable on a commercial job. A low, flat-roofed retail unit with good hard standing around it costs far less to scaffold or access than a high-pitched agricultural barn with soft ground, livestock inside or no clear platform for a tower or cherry picker. Access costs on a difficult site can add 20 to 40 per cent to the overall price compared with an easy one.
The condition of the existing deck or structural frame matters enormously. If a flat roof deck is rotten, it must be replaced before the new membrane goes on, and the cost of replacing OSB or plywood decking adds to the job. On a metal-framed building, corroded purlins or rail sections discovered during strip-out can add significant cost that could not have been foreseen before work started. Always ask your contractor what happens if structural problems are found during strip-out and how additional costs would be agreed.
Roof complexity adds cost. Every penetration, vent, roof light, pipe or conduit through a flat roof is a potential leak point and must be carefully dressed when the membrane goes on. A clean rectangular roof with one or two outlets and no penetrations is far cheaper per square metre than one with a dozen roof lights, multiple service penetrations and a complex profile.
Insulation specification affects price significantly. Many older commercial flat roofs have little or no insulation beneath the covering. Adding a rigid foam insulation layer when the roof is being replaced is far cheaper than doing it later, and it reduces heating costs. The thickness required to meet current building regulations for a commercial building is now substantial, and the cost of 100mm or more of rigid insulation board across a large roof area adds meaningfully to the total.
The time of year and workload across the trade affect availability and sometimes pricing. Roofing contractors are typically busiest in summer and autumn, and emergency repairs following storm damage in winter can stretch the availability of good contractors. Planning non-urgent replacement work for quieter periods sometimes produces better pricing.
A simple roof with good access, a sound existing deck and minimal detailing is the cheapest type of commercial roof job. Combining work, such as replacing a roof at the same time as renewing all guttering and flashings, reduces mobilisation costs compared with returning to site multiple times.
Coating or over-roofing an existing metal or felt roof rather than stripping and replacing it can reduce costs significantly where the substrate is sound enough to carry another layer. A coating system applied to a clean, prepared metal roof can add years of service for a fraction of a full re-cladding cost. The condition of the substrate must be properly assessed first, though: coating over a failing structure just delays the problem.
Using a contractor based locally to Horsford, working from Dereham or nearby, reduces the travel and mobilisation element of the price compared with bringing in a contractor from Norwich or further afield. For smaller jobs especially, the distance a crew must travel to site affects whether a job is viable at a competitive price.
A commercial roofing quote should always be itemised. You should be able to see the area being covered, the specification of materials, the method of installation, the provision for stripping and disposing of old material, and the scope of work on gutters, flashings and any ancillary elements. A lump-sum figure with no breakdown gives you no basis for comparison or for understanding what you are paying for.
Ask about provisional sums. On commercial jobs with an unknown substrate condition, a reputable contractor will include a provisional sum for structural repairs and tell you clearly how that sum will be calculated and agreed if structural problems are found. This is standard practice and protects both parties.
Commercial guttering handles far more water than domestic systems. A 500 square metre flat roof drains a significant volume of water during heavy rainfall, and the gutter and downpipe sizes must be calculated for that load. Half-round domestic gutters are unsuitable for most commercial applications. Box section gutters, valley gutters and parapet gutters are common on commercial and industrial buildings, and they need to be properly supported, jointed and pitched to drain freely.
Aluminium guttering is the most common modern choice for commercial buildings: it does not rust, handles thermal movement better than rigid UPVC on long runs and is available in large section sizes suited to commercial roof areas. Older properties may have cast-iron guttering, which can be repaired and is worth preserving on buildings where it suits the character, but which is expensive to replace like-for-like.
Gutter maintenance, including clearing debris from outlets and checking joints and fixings, is worth doing every year or two on most commercial buildings. Blocked commercial gutters cause problems quickly, particularly on flat-roofed buildings where the gutter is the only drainage path.
For straightforward commercial roof surveys, repairs and replacements, contact us to arrange a visit and a written quote. Be ready to describe the building type, approximate roof area and what you have already noticed, as this helps us give you a realistic expectation of cost and timescale before we arrive on site.
For larger replacement projects, it is worth getting two or three quotes and checking that each one is priced against the same written specification. If quotes differ significantly, the reason is usually a difference in specification rather than a difference in contractor efficiency, and it is worth asking each contractor to explain what their quote includes and what it does not.
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Call any time. Calls are answered day and night and passed straight to our roofers.
