- Guide price
- £750–£1,300
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Cornwall at a glance
How much does a porch or bay roof cost in Cornwall?
Guide prices including VAT at South West rates. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Porch or bay (4 m²), EPDM | £750–£1,300 |
| Single garage (18 m²), EPDM rubber | £1,650–£2,900 |
| Extension (20 m²), GRP, new deck + insulation | £3,100–£5,550 |
Which flat roofs are common in Cornwall?
Flat roofs in Cornwall sit on bungalows with flat-roofed side extensions and dormers, newer estates where the first extension roofs are now being replaced and terraced streets with flat-roofed rear kitchens and bathrooms. The South West averages roughly 1,260 mm of rain a year and many roofs face wind off the Atlantic, so we specify fixings and edge details for wind uplift as well as drainage. Approximate 1991–2020 regional averages based on Met Office data.
Building regulations in England
Replacing more than half of a roof over a heated room usually counts as renovating a thermal element, so it is insulated to current standards and notified to building control. Renovated roofs over heated rooms are insulated to around 0.16 W/m²K where that's feasible, and new extension roofs are built to 0.15 W/m²K. In Cornwall the application goes to Cornwall Council. More on the rules.
Do I need permission to re-roof a porch or bay?
Usually not. Re-covering a porch or bay roof without materially changing how it looks does not normally need planning permission, and an unheated open porch is not usually a thermal element.
The picture changes if the bay or porch is part of a heated room: replacing most of the roof can then bring it under the insulation rules for renovated roofs, which may need building control approval in England, a check in Wales, building standards in Scotland or district council building control in Northern Ireland. On a very small roof, adding insulation may not be technically feasible because of the height available below the window sill above. We assess that at survey.
Listed buildings need consent for changes that affect their character, and conservation areas can restrict changes to the front of a house. See our building regulations page for more detail.
Why do small porch and bay roofs carry a minimum charge?
Because a small roof needs nearly the same set-up as a larger one: a team, safe access, materials, trims, waste removal and travel. The roof area is only part of the cost.
A 2 m² canopy and a 6 m² bay still both need a full strip, a deck check, edge trims, a wall flashing and the same care at the drip edge. That is why our full re-roofs carry a minimum charge rather than being priced purely per square metre. It is also why bundling makes sense: if you have a porch, a bay and a garage, pricing them together usually works out better than three separate visits.
The junction with the house wall deserves the most attention on a porch. Many leaks blamed on a porch roof are actually water tracking behind a failed flashing or through porous brickwork above. We check the wall, the flashing and the frame head before recommending a new roof. If the problem is only the flashing, a targeted repair may be enough. Our flat roof leaks guide explains how leaks are traced.
Which towns in Cornwall do we cover?
Porch, bay and canopy roofs in Cornwall: questions
Which towns in Cornwall do you cover?
All of Cornwall. The main towns have their own pages below, and if yours isn't listed we still cover it: send your postcode and we'll confirm.
How much does a porch or bay roof cost in Cornwall?
£750–£1,300 for a small 4 m² porch or bay roof in EPDM, at South West guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Which postcode areas do you cover in Cornwall?
All of Cornwall, including the PL, TR postcode areas. Send your full postcode and we'll confirm.
Can a bay window roof be replaced without scaffold?
A ground-floor bay usually can, using a tower or platform. A first-floor bay generally needs a small scaffold for safe access.
Does a porch roof need a gutter?
Not always. Many small porches drip straight off the front edge, but a gutter helps over a doorway or path.
Can you re-roof a porch and a garage on the same visit?
Yes, and it is often better value. Combining small roofs spreads the set-up and travel costs.
Everything about porch, bay and canopy roofs → · All flat roofing in Cornwall →