- Guide price
- £750–£1,300
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Wiltshire at a glance
- Largest towns
- Swindon, Salisbury, Trowbridge, Chippenham
- Postcode areas
- BA, SN, SP
- Building control
- Swindon Borough Council and Wiltshire Council
- Neighbouring areas
- Bristol · Gloucestershire · Somerset · Dorset
- Guide price region
- South West (+3% on West Midlands rates)
How much does a porch or bay roof cost in Wiltshire?
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 Wiltshire?
Flat roofs in Wiltshire sit on 1960s and 1970s link-detached houses with flat-roofed garages and porches, 1930s semis with flat-roofed garages and kitchen extensions 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 Wiltshire the application goes to Swindon Borough Council and Wiltshire Council. More on the rules.
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.
How long does a porch roof replacement take?
Most porch and bay roofs are replaced in a single day, weather permitting. GRP or liquid systems may need a return visit for a topcoat once the first coat has cured.
Disruption is minimal. You may need to use another door while a front porch is being re-roofed, and the area below should be kept clear for safety. A ground-floor bay can usually be reached from a tower or platform steps, while a first-floor bay may need a small scaffold. The window below stays usable, though it is best kept closed while resin is curing.
Which towns in Wiltshire do we cover?
Porch, bay and canopy roofs in Wiltshire: questions
Which towns in Wiltshire do you cover?
All of Wiltshire. 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 Wiltshire?
£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 Wiltshire?
All of Wiltshire, including the BA, SN, SP postcode areas. Send your full postcode and we'll confirm.
How long will a new porch roof last?
With good specification and maintenance, EPDM is indicatively 25–50 years and GRP 20–40.
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.
Should I replace lead on my bay roof with EPDM or GRP?
It depends on the house and your priorities. Membranes usually cost less and have no scrap value to thieves, but on a period or listed property keeping a lead appearance may matter or be required.
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