The short answer
How much does roof insulation cost on a commercial building? Typical method figures are £16 to £35/m² + VAT for 25 to 50 mm closed-cell foam from below, £20 to £30/m² for mineral wool on a liner and £30 to £50/m² for PIR on a new liner. Compare the complete scope, not just the rate.
Typical UK industry figures, 2026. Send photographs or drawings for a free estimate.
For a budget holder, the real question is what the building will cost to improve. A low rate can sit beside access hire, a new liner, stock moves or weeks of disruption. Start with the roof's condition and the job it needs to do. Then compare methods on the same scope.
This guide covers commercial roofs. For a house loft, impartial home energy advice services publish domestic costs. Our cost guide covers HOLVEM's foam bands in detail; this page puts them beside the other commercial methods.
01Cost per m², by method
Commercial roof insulation cost per m², by method
Here are the approved planning figures in one place. The foam bands have a stated VAT basis. The alternative insulation-method figures do not, so ask the quotation to make that clear rather than assuming the table puts everything on the same tax basis.
| Method | Typical cost per m² | Scope to compare | Costs to check | Building in use during work |
|---|---|---|---|---|
| Closed-cell foam from below | £16 to £35 + VAT for 25 to 50 mm. | An underside insulation layer to the specified depth; HOLVEM's spray foam prices per m². | Access, preparation, masking and any specified fire coating. | Yes, in agreed areas outside the active work bay; programme confirmed for the job. |
| Mineral wool on a liner | £20 to £30 installed. | Supported insulation and liner construction. | Vapour control, access, clearing the floor and service details. | Partly, subject to the installation and protection plan. |
| PIR boards on a new liner | £30 to £50 installed. | Board insulation and new liner construction. | Cutting, fixing, vapour control and work around obstructions. | Partly, subject to the programme and available work areas. |
| Overcladding | £60 to £90. | A new roof system above the retained covering. | Roof access, edge protection, structural checks and re-detailing. | Partly, according to the roof-work and protection plan. |
| Insulated panels or full replacement | £100 to £160. | New panels or replacement roof construction. | Strip-out, scaffold, weather protection, disposal and downtime. | No in an exposed work area while the covering is off; phasing is a project decision. |
| Asbestos removal and disposal only | Large, straightforward roof: £20 to £40 + VAT. Small, damaged, fragile or hard-to-reach: £60 to £100 or more. | Removal and disposal by asbestos removal professionals. Remove and replace: £100 to £160 + VAT. | Scaffold and access usually extra; replacement is a separate scope from removal alone. | No in the active removal area; the contractor specifies protection and phasing. |
Typical UK industry figures, 2026. Send photographs or drawings for a free estimate.
HOLVEM does not test for asbestos or replace roof sheets, and never removes asbestos sheets. If the roof is safe to keep, we encapsulate it; if not, removal is a job for asbestos removal professionals, licensed where HSE requires it.
These are route comparisons, not six interchangeable treatments. Removal does not insulate a roof. A new roof system does more than add insulation. A retained-roof layer does not supply a new covering. Decide which construction you need before reading down the cost column.
Typical cost per m², by method
02What each method includes
What each method includes, and what it leaves out
To compare quotations fairly, describe the finished roof you expect. Where is the insulation? What supports it? How are the joints and edges detailed? Does the quote keep the existing roof covering, add another one or replace it?
What stays, what is added, what comes off
Closed-cell foam from below
- Existing covering
- Kept, as found
- Insulation
- Bonded beneath the sheet
- Outer covering
- None added
Mineral wool or PIR on a liner
- Existing covering
- Kept, as found
- Insulation
- On a new inner liner, with vapour control
- Outer covering
- None added
Overcladding
- Existing covering
- Kept beneath
- Insulation
- In the new system above
- Outer covering
- New, above the old
Insulated panels or full replacement
- Existing covering
- Removed
- Insulation
- In the new construction
- Outer covering
- New
A sprayed underside layer follows a suitable existing profile. It is applied in place, with the depth, preparation and any coating specified for the project. It does not supply a new outer roof covering. If the roof is sound and the objective is condensation control or improved thermal performance, that retained construction can be the useful comparison.
Mineral wool or PIR on a liner brings an inner skin and its supports into the job. Include vapour control and the work around purlins, rooflights and services. These systems do not, simply by being installed, seal the existing outer sheet laps and fixings. Their weathering condition still matters.
Overcladding changes the roof from above. The structural check, added load and details at rooflights, ridges and gutters belong to that design. Replacement goes further: the covering comes off and a new construction takes its place. Where the original roof cannot stay, that broader scope is necessary rather than an optional expensive extra.
Our spray foam versus overcladding guide compares those two routes in detail. For the materials rather than the price, use the dedicated roof-insulation-types guide when it is live.
04What moves the price
What moves the price on your roof?
Once the method is agreed, the building explains where its quotation sits. These seven items help you read the scope and compare what each contractor has allowed for.
- 1. Area. Larger roof areas usually spread setup costs further. Use the actual treated area, including the agreed approach to profiles and openings.
- 2. Access and working height. Allow for the lift, tower or other access arrangement, and whether the floor is clear or occupied by stock and equipment.
- 3. Roof make-up. Profiled metal, fibre cement, asbestos cement, a deck and a concrete soffit are different substrates and constructions.
- 4. Depth. It is typically 25 mm or 50 mm closed-cell, depending on the roof make-up, confirmed before we spray, with a condensation risk analysis where needed. Depths of 75 mm and above are priced per project.
- 5. Preparation. Include cleaning where required, loose or corroded areas, and protection of stock, lighting and services. Roof washing is only preparation before a coating, never a standalone HOLVEM service.
- 6. Fire coating. Where the fire strategy, insurer or warranty needs a coated system, the coating is priced on top of the foam for the project.
- 7. Rooflights. Each is masked and left clear so daylight is retained. The protection and surrounding details belong in the scope.
For a thermal target, ask how the proposed depth follows the roof's thickness and objective. For fire, request the tested build-up and coating evidence. That turns a line saying “insulation” into work a surveyor can review.
05A worked example
A worked example: a 1,000 m² roof
Here is one calculation to show the scale of the method comparison. It uses the approved bands without narrowing them to a made-up average. Indicative planning figure, not a quotation.
For 50 mm closed-cell applied from below:
- 1,000 m² × £22 = £22,000.
- 1,000 m² × £35 = £35,000.
- The band is £22,000 to £35,000 + VAT, or £26,400 to £42,000 including VAT at 20%.
For that same 1,000 m² roof, overcladding at £60 to £90/m² gives £60,000 to £90,000. Panels or replacement at £100 to £160/m² gives £100,000 to £160,000. The alternative figures have no VAT basis stated in the approved comparison; request it in the quotation.
One roof, 1,000 m² · not a quotation
Then check what the rate leaves out: access, scaffold, downtime and disposal where relevant. This is a scale comparison, not proof that every route does the same job. See HOLVEM's spray foam prices per m² for the depth bands and how a typical warehouse sits within the quoted scope.
06Asbestos-cement roofs
Asbestos-cement roofs: removal, or keep and encapsulate
An asbestos-cement roof adds a question before insulation pricing: can the sheets remain? Obtain the asbestos survey or register and assess the condition. A roof that is safe to retain can be considered for encapsulation. If it cannot stay, price the removal and replacement programme with the appropriate professionals.
HOLVEM does not test for asbestos or replace roof sheets, and never removes asbestos sheets. If the roof is safe to keep, we encapsulate it; if not, removal is a job for asbestos removal professionals, licensed where HSE requires it.
On our 2,340 m² asbestos-cement roof project, we applied 50 mm closed-cell from below without walking on, cutting, drilling or removing the sheets. The customer reported: “Condensation on the roof underside was mitigated following installation.” Retaining the sheets avoided introducing a removal-and-disposal scope to that job.
The comparison is construction-led. You cannot price a failed roof as though it were a sound one simply because the retained-roof option is lower. For the work by others, the asbestos roof removal cost guide separates removal-only costs from the replacement roof.
07The cheapest route
When the cheapest route is the wrong one
Before approving the lowest figure, return to the roof condition and required outcome. An active leak, unsound construction or a fire strategy the proposed build-up cannot meet changes the job. A thermal layer cannot supply a structural repair or a new roof covering.
If the roof leaks, call a roofer first. HOLVEM is not a roofing contractor, and spray foam is not waterproofing. See commercial roof repair and the cost guide's suitability checks before choosing an insulation method.
For condensation, the source of the water needs diagnosing. For heat loss, the proposed build-up needs calculating. That gives the quotation a defined task, rather than leaving everyone to assume what a depth of foam is meant to achieve.
08Projects
Projects: what the programme looks like
Real projects help explain the price factors without inventing a saving for your roof. At TJW Grab Hire, Bournemouth, about 505 m² of steel roof received 50 mm closed-cell in two working days. Rooflights were masked and kept clear. The customer reported stopped condensation and a warmer, drier building.
At the Midlands distribution warehouse, the roof underside was treated bay by bay while the warehouse remained open. The client reported stopped condensation and a substantial fall in energy use and cost. The working programme shows how installation can be coordinated with an occupied building; it does not give every warehouse a two-day programme or a fixed saving.
09Getting a price
Getting a price for your roof
You can start before arranging a site visit. Five photographs often get you a free, same-day estimate, no survey needed. Drawings can also help us understand the roof. Include roof views, any available drawings and the building objective so we can understand the work you are comparing.
The virtual survey is part of that free estimate. We can measure and check the roof remotely from aerial imagery alongside your photographs or drawings. Straightforward jobs are confirmed on install. Larger or complex jobs receive a free survey, then a firm written quote. No obligation either way.
