Flat Roof Installers: what the job involves and who is registered to do it

How flat roofing works

1. Read the existing deck. Almost every flat roof failure starts below the waterproofing: a sagging deck holding water, a fall that runs the wrong way, or a rotten firring. Laying a new membrane over a soft deck buys a few years at full price.
2. Choose the system for the detail, not the brochure. Fibreglass suits a small roof with simple upstands and hates movement. Rubber membranes take movement well and want careful bonding at the edges. Reinforced bitumen is forgiving on a complicated roof. Single ply is a commercial system that wants a trained installer.
3. Get the falls and outlets right. Standing water is what turns a small defect into a leak, so the falls, the outlet positions and the upstand heights matter more than the brand of the covering. Ask what the finished falls will be and where the water is going.
4. Insulate in the right place. A warm deck puts the insulation above the structure and keeps the deck warm and dry; a cold deck puts it between the joists and needs ventilation that is easy to block. Which one you get changes both the price and the condensation risk.
5. Ask what the guarantee actually covers. Manufacturer guarantees on flat roof systems usually depend on an approved installer and correct detailing, so the paperwork is worth as much as the membrane. Get the guarantee terms before the work, not after.

Insurance and paperwork

Common questions

How long should a flat roof last?

It depends far more on the deck, the falls and the detailing than on the covering, which is why published lifespans vary so widely between the same product on two roofs. A well laid roof on a sound deck with real falls outlives a premium membrane on a ponding one.

Can a flat roof be converted to a pitched roof?

Often yes, and on a garage or a small extension it is a common way to end a repeated leak. It is a structural alteration, so it is controlled work and may need planning permission depending on the height and the position.

Is a flat roof cheaper than a pitched roof?

Per square metre a flat roof is usually cheaper to build and more expensive to own, because it has a shorter service life and less tolerance of poor detailing.

Registered contractors by region

• Registered roofers in the East Midlands postcode area
• Registered roofers in the East of England postcode area
• Registered roofers in the London postcode area
• Registered roofers in the North East postcode area
• Registered roofers in the North West postcode area
• Registered roofers in the Scotland postcode area
• Registered roofers in the South East postcode area
• Registered roofers in the South West postcode area
• Registered roofers in the Wales postcode area
• Registered roofers in the West Midlands postcode area
• Registered roofers in the Yorkshire and The Humber postcode area