Roof overcladding
New metal roof over old sheets · building stays in use
Overcladding builds a new insulated metal roof on top of an existing one. Brackets fix through to the purlins, rails sit on the brackets, insulation fills the gap and new profiled sheets go over the top. Published prices run £45 to £65 per m², which on a 2,000 m² unit is about £90,000 to £130,000.
Nothing is stripped, so the building stays watertight and in use. For asbestos cement roofs, the old sheets stay sealed in place rather than being disturbed.
When overcladding is the answer
Corroded sheets on a sound frame
The purlins and steel frame are in good order; the sheets are not.
Asbestos cement sheets
Leaving sheets in place under a new roof avoids the cost and risk of removal.
No insulation today
Single-skin roofs gain insulation and lose condensation drip.
The building cannot close
Work happens above the old roof, which keeps the weather out throughout.
Overcladding costs
| Item | Scope | Typical cost |
|---|---|---|
| Overclad over sound sheets | Brackets, rails, insulation, new sheets | £45 to £65 per m² |
| 1,000 m² roof | Worked from the per m² rate | £45,000 to £65,000 |
| 2,000 m² roof | Worked from the per m² rate | £90,000 to £130,000 |
| Compare: strip and re-roof | New profiled sheets on the existing frame | £65 to £85 per m² |
| Compare: remove asbestos sheets | Removal and hazardous waste disposal, extra over | £25 to £90 per m² |
Budget figures read from national price guides and roofers' own published rates in November 2026, shown before VAT. Use them to plan; the contractor's written price is what counts. Work out a budget for your roof.
How overcladding works
The bracket and rail system
Spacer brackets are fixed through the old sheets into the purlins, set to the depth of insulation required. Rails run across the brackets and the new sheets fix to the rails. The loads go into the existing frame, which is why a structural check comes first.
Insulation and condensation
Mineral wool or similar insulation fills the space between the old and new skins, taking a single-skin roof to modern standards. The old sheets usually act as the liner; a vapour control layer may be added.
Asbestos cement roofs
Fixing through fibre cement sheets disturbs them a little at each fixing point. That work is planned under the Control of Asbestos Regulations, with the fixing method and controls in the method statement. The old sheets remain fragile: overcladding is done from the new rails and safety systems, not by walking on them.
Rooflights and gutters
Rooflights are renewed as part of the new roof, and the gutters are usually lined or replaced at the same time. Both are common sources of later trouble if left out of the scope.
Where our information comes from
- GOV.UK, Approved Document L: conservation of fuel and power (2021 edition)
- HSE, Non-licensed work with asbestos (updated February 2024)
- HSE, Asbestos essentials task sheets for asbestos cement
- HSE, Fragile surfaces
Prices are typical ranges from published UK contractor price guides and roofing firms' price pages, November 2026.
Corroded or asbestos roof? Get overcladding priced by a contractor who covers your area.
Get contractor quotesHow the job runs
A typical overclad on an occupied unit.
Survey
A contractor walks the roof where it is safe to, or flies a drone where it is not, takes cores on flat roofs and photographs every defect. You get a written report with a recommendation.
Structural and asbestos checks
Frame capacity confirmed and the old sheets assessed.
Specification and price
A written scope naming the system, the details at edges, outlets and rooflights, the guarantee and the programme, with a fixed price excluding VAT.
Brackets, rails, insulation, sheets
Fixed in bays from safe working platforms, rooflights and gutters dealt with as the roof progresses.
Handover
A final inspection, photographs, the guarantee certificate, building control completion where it applies, and a note of when the next maintenance visit is due.
Overcladding questions
How much does roof overcladding cost?
- Published prices for overcladding over sound non-asbestos sheets run £45 to £65 per m², excluding VAT. A 1,000 m² roof works out at about £45,000 to £65,000. Asbestos roofs, rooflight and gutter work and difficult access add to it.
Can you overclad an asbestos roof?
- Yes, it is one of the most common reasons for overcladding. The old sheets stay in place, sealed under the new roof, and fixing through them is planned under the asbestos regulations.
Is overcladding cheaper than replacing the roof?
- Usually, especially on asbestos roofs where removal and disposal add £25 to £90 per m². On a non-asbestos roof the gap is smaller: strip and re-roof is £65 to £85 per m².
Does overcladding need building regulations approval?
- It is roof renovation, so the energy rules apply and building control is normally notified. The new roof should meet the current U-value where feasible, which overcladding usually achieves easily.
How long does an overclad roof last?
- As long as a new metal roof: typically 25 to 40 years, set largely by the sheet coating. Some pre-finished steels carry coating guarantees up to 40 years.
Read next
- Industrial roofing
Metal, panel and fibre cement roofs.
- Cut edge corrosion treatment
If the sheets can be saved.
- What is a fragile roof?
Why nobody walks on old sheets.
- Commercial roof cost calculator
Overclad against re-roof.
Get overcladding priced
Three short steps. The postcode, what the roof is and what it is doing is enough to start. A contractor confirms the detail on a survey.
Your request stays with us until you approve the independent commercial roofing contractor we put forward for your building.
Received. Here is what happens next.
- We look for an independent commercial roofing contractor who covers your area and takes on roofs like yours, then email or phone you with their name.
- Nothing goes to them until you say yes.
- If you agree, they arrange a survey and send a written price. No newsletters and no sales calls from us.