Flat Roof Installation
Flat Roof Installation Built to Actually Last
Extensions, garages and outbuildings all need flat roofing that copes with standing water and UK weather. We install systems built for the long term, not the cheapest possible fix.
- Fully insured tradespeople
- 10-year workmanship guarantee
- Rapid emergency response
- Locally based in Welwyn
Signs you need this service
- You're planning a new extension, garage or outbuilding that needs a flat roof
- An existing felt roof is bubbling, cracking or ponding water
- Visible patch repairs on an old flat roof that keep failing
- Daylight or damp visible in a flat-roofed extension ceiling
- A flat roof older than 15-20 years that has never been replaced
Our process
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1
Assess the structure
We check the roof deck and falls to make sure water will drain properly rather than pool.
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2
Recommend the right system
We advise between GRP (fibreglass) and modern felt systems based on your budget, roof size and how the space is used.
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3
Install
The chosen system is installed with correct falls, edge trims and upstands to prevent the ponding and leaks that shorten a flat roof's life.
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4
Sign-off
We walk you through the finished roof and provide guarantee documentation for the installed system.
Why choose CS Roofing
- GRP and felt systems, fitted to manufacturer specification
- We correct poor falls that cause ponding, not just recover the same problem
- 10-year workmanship guarantee
- Experience with extensions, garages and outbuildings alike
Frequently asked questions
What's the difference between GRP and felt flat roofing?
GRP (fibreglass) is a single seamless waterproof layer with a longer typical lifespan; felt systems are more cost-effective and well-proven for smaller structures. We recommend based on your specific project.
Why does my flat roof keep getting standing water?
This is almost always caused by insufficient fall (slope) in the original installation. We correct the falls as part of any replacement rather than just laying new material over the same problem.
How long does a flat roof installation take?
A typical domestic extension or garage flat roof can usually be completed within one to three days, weather permitting.
Can you install a flat roof on a new extension as part of the build?
Yes, we regularly work alongside builders on new extensions to install the flat roof at the right stage of the project.