Repair, refurbish or replace: comparing the three kinds of roofing quote
Ask three roofers to look at the same tired commercial roof and you may get three different answers: a repair, a refurbishment such as an overlay or coating, and a full replacement. The prices are not comparable until you know which answer fits the roof. This page sets out how to tell, what each kind of quote must state, and how to put a repair price next to a replacement price fairly.
Three answers to one roof
| Kind of quote | It fits when | It must state |
|---|---|---|
| Repair | The failure is local and the rest of the roof, its insulation and its falls are sound | The cause of the leak, the area repaired, what was not inspected, and any warranty on the repair |
| Refurbishment (overlay, over-sheet, coating, gutter lining) | The deck and structure are sound and dry, but the covering is near the end of its life | Evidence the substrate is dry, the structural check for added load, the expected extra life and the guarantee terms |
| Replacement (strip and re-roof, re-clad) | The insulation is wet, the deck is failing, the roof ponds, or repairs keep failing | The new build-up and U-value, the falls design, the access and phasing plan, asbestos arrangements and the guarantee |
The evidence that decides between them
The choice turns on what is under the covering, so the first thing to compare is the evidence each roofer has gathered. A repair quote written from the ground, a refurbishment quote with no moisture readings, and a replacement quote with core samples are not three opinions of equal weight. Ask each firm what it inspected and how:
- Moisture in the insulation. Core samples or a non-destructive moisture survey. Wet insulation cannot be overlaid; it loses its thermal value and can rot a timber deck or corrode a metal one.
- The deck. Deflection, corrosion of metal decks, rot in timber, cracking in concrete. An overlay adds weight to whatever is there.
- Falls and ponding. Standing water after rain means the roof was not laid to fall or has deflected. A repair will not fix that; refurbishment can, with tapered insulation; replacement always should.
- Gutters and cut edges. On profiled-metal roofs, failed gutter joints and corroded sheet ends often cause leaks that look like a roof failure. Check this before accepting a re-clad as the only answer.
- Asbestos. On buildings from before 2000, HSE guidance expects a refurbishment survey before work that disturbs the fabric. Asbestos cement sheets can change the choice from over-sheeting to removal.
Putting a repair price next to a replacement price
A repair is cheaper today and a replacement lasts longer, so comparing their prices directly favours whichever horizon you happen to pick. Compare them on the same basis instead:
- Write down the price, the service life the roofer expects, and the guarantee term and backer for each option.
- Add the repairs you are already paying for each year on the current roof, from your maintenance records.
- Ask what the repair option leaves untouched: insulation, falls, gutters. Those costs come back later.
- Check the regulations. Renewing most of a roof normally triggers the Part L insulation upgrade for a renovated thermal element under Approved Document L, which is part of a replacement price and not of a repair.
- Factor in disruption. A failed roof over stock, production or a classroom costs more than the roofing invoice.
The answer is not always replacement. On a sound roof with a short ownership horizon, a well-specified repair or coating can be the honest choice. The point is to compare like with like: each option's cost over the period you care about, with the risk it leaves in place.
When the three roofers disagree
If one firm quotes a repair and another a full replacement for the same roof, ask each to explain the other's option. A roofer who can say why an overlay will not work on your roof, with evidence, is giving you more than one who simply prices the bigger job. If the evidence is thin on both sides, an independent condition survey before you commit can settle it.
Lines to check on every option
- The roof area covered, measured the same way on every quote.
- Access, edge protection and fragile-roof measures for working at height.
- The guarantee: issuer, cover, term, and whether it survives the contractor.
- Building control: who handles it, or whether the firm can self-certify through a competent person scheme such as CompetentRoofer.
- Exclusions and provisional sums, especially for deck repairs and asbestos.
The quote sense-check puts up to three options side by side as a price per square metre, and our cost guide explains each line that moves the price.
Repair or replace: common questions
How do I know if my commercial roof can be overlaid?
Only with evidence: the existing insulation must be dry, the deck sound, and the structure able to carry the added load. Ask for core samples or a moisture survey and a structural check before accepting an overlay quote.
Is it cheaper to repair or replace a commercial roof?
A repair costs less today. Whether it costs less overall depends on how long it lasts, what it leaves unfixed and what failures cost your business. Compare each option's price, expected life and guarantee over the period you will own or occupy the building.
Does replacing a commercial roof need building regulations approval?
Renewing most of a roof is normally building work, including the Part L insulation upgrade for a renovated thermal element. A firm registered with a competent person scheme such as CompetentRoofer can self-certify qualifying work; otherwise a building control application is needed.
Sources: Approved Document L (gov.uk), HSE asbestos and roof-work guidance, CompetentRoofer scheme. Last checked 25 October 2026. Commercial Roofing Quotes is an independent publisher run by SEO Dons Ltd and does not survey, price or install roofs.