- Price per m²
- £93–£149
- Typical life
- 25–35+ years
- Manufacturer guarantees
- 20–25 year guarantees on specified systems
- Typical garage roof
- £2,100–£3,450
Cornwall at a glance
How much does a single-ply 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 |
|---|---|
| Commercial roof (100 m²), single-ply + insulation | £13,650–£22,450 |
| Single garage (18 m²), single-ply | £2,100–£3,450 |
| Single garage (18 m²), EPDM rubber | £1,650–£2,900 |
| Extension (20 m²), EPDM, new deck + insulation | £2,900–£5,050 |
Which flat roofs are common in Cornwall?
Flat roofs in Cornwall sit on 1930s semis with flat-roofed garages and kitchen extensions, terraced streets with flat-roofed rear kitchens and bathrooms and bungalows with flat-roofed side extensions and dormers. 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.
Should a single-ply roof be mechanically fixed or adhered, and how are the seams welded?
Most commercial single-ply roofs are mechanically fixed, while adhered systems suit decks that cannot take fixings or roofs where a smooth finish is wanted. The choice depends on the deck, the wind exposure of the site and the manufacturer's specification.
| Method | How it works | Typical use |
|---|---|---|
| Mechanically fixed | Fasteners and plates hold the membrane through the insulation into the deck, hidden under the lap of the next sheet | Metal, timber and concrete decks on commercial roofs |
| Adhered | Membrane bonded to the insulation or deck with adhesive | Domestic roofs, roofs where fixings are unsuitable |
| Ballasted | Loose-laid and held down by paving, gravel or a green roof | Inverted roofs, terraces, green roofs |
Fixing patterns are worked out for the site, with more fasteners at corners and perimeters, where wind uplift is strongest.
Seams are welded by hot-air machines and hand tools that melt the overlapping edges so they fuse. Each seam is then probed along its length to find any gaps, and test welds are made at the start of the day to set the machine for the weather. On commercial jobs we also check that walkways protect the membrane around plant.
Is single-ply the right system for my roof?
Single-ply is usually the right system for medium and large flat roofs, such as shops, offices, units, surgeries, clubs and blocks, where speed of installation, light weight and long life matter. On a small domestic roof it can work well, though it is not always the most economical choice.
In its favour: lightweight; quick to lay over large areas; flame-free, as the seams are welded with hot air; long typical life; welded details at rooflights and plant; lighter-coloured membranes reflect more sunlight.
Against it: only one waterproof layer, so welding quality is critical; can be punctured by foot traffic or dropped tools without walkway protection; PVC needs separating from bitumen; repairs need compatible material and welding equipment.
For a small garage or extension, EPDM is often simpler. Where people walk regularly, GRP or a liquid system may be tougher. A multi-layer torch-on felt roof gives built-in redundancy, and on older buildings mastic asphalt may be the original material. Our commercial flat roofing page covers larger jobs.
Which towns in Cornwall do we cover?
Single-ply membrane roofing 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 single-ply roof cost in Cornwall?
£13,650–£22,450 for a 100 m² commercial roof in single-ply with insulation, 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.
What is the difference between PVC and TPO roofing?
Both are thermoplastic single-ply membranes welded with hot air. PVC contains plasticisers and usually needs separating from bitumen, while TPO and FPO are polyolefin-based; the right one depends on the roof and the system specified.
Can a single-ply roof be repaired?
Yes. A compatible patch is cleaned and hot-air welded over the damage. Older membranes may need extra cleaning before they weld properly, which the team checks on site.
Is single-ply roofing noisy in the rain?
No more than other flat roofs. Noise depends far more on the deck and insulation than on the membrane, and an insulated warm roof dampens rain noise well.
Everything about single-ply membrane roofing → · All flat roofing in Cornwall →