Services / Flat Roof Replacement
Flat roof replacement in London & surrounding counties
Most flat roofs don't actually need replacing. They need re-waterproofing. Perlini installs the Ultraflex overlay system across London, giving you the performance of a brand-new roof at up to 50% less cost than a traditional strip-and-replace. If a full roof replacement is required, our experienced team has the expertise to design and construct both warm and cold roof systems. With skilled carpenters and roofing specialists, we can carry out a complete roof rebuild to the highest standards.
- Saturated insulation
- Soft or rotten deck
- Roof beyond repair
- Insulation upgrade needed
The problems with a full flat roof replacement
Tearing off and replacing a flat roof with another traditional system (GRP, EPDM, felt or single-ply) is expensive, disruptive and rarely necessary. Most existing decks are sound. It's the waterproofing layer that's failed.
High cost and waste
Full strip-outs mean skip-loads of waste to landfill, more materials, more labour and significantly higher cost than overlaying the existing roof.
Days or weeks of disruption
Stripped roofs leave the building exposed to weather, with scaffold, noise and access issues for far longer than an overlay install.
Exposure to the weather mid-job
Once the old roof is off, any rain risks soaking insulation, deck and ceilings below, a real risk on UK projects.
Same weak systems re-installed
Replacing with GRP, felt or EPDM just resets the clock on the same multi-layer, seamed systems that failed in the first place.
Sound decks thrown away
Most existing decks and insulation are still serviceable. A full replacement bins materials that a cold-liquid overlay would have protected for another 20 years.
Why a full strip-out usually isn't necessary
A traditional replacement means tearing off your existing roof, exposing the building to the weather, generating skip-loads of waste and weeks of disruption. With our waterproofing system, we inspect, repair, and overlay the existing roof with a fully bonded, seamless layer that's rainproof in 30 minutes, giving you the performance of a new roof at a fraction of the cost.
Of course, if a full roof replacement is genuinely required, we are fully equipped to strip the existing roof back and rebuild it from the structure up. Our team is experienced in constructing all types of flat roof systems and works in accordance with the latest building regulations.
One of the best flat roof waterproofing systems on the market
Whatever flat roof job you have (installation, repair, replacement, or an asphalt, GRP, EPDM or torch-on felt overlay), we install the Ultraflex cold-liquid waterproofing system. It's the most durable, cost-effective, and reliable flat-roof solution available.
By overlaying your existing roof with Ultraflex, we save you the cost and disruption of a full strip-out while delivering a fully bonded, seamless waterproof layer backed by a 20-year guarantee. We go in, repair your existing roof and seal it for decades of protection. If needed, we can apply bespoke finishes and solutions post-waterproofing.
Why we install Ultraflex on every job
Faster installation
Fast-curing and rainproof in as little as 30 minutes.
Up to 50% cost savings
Overlay your existing roof and avoid strip-out costs.
20-year guarantee
Proven waterproofing built for long-lasting protection.
100% Compatible
Torch-on felt, asphalt, GRP, timber, concrete, and virtually any roof surface.
Safer installation
Cold-liquid application, eliminating fire risk.
Seamless waterproofing
No joints or laps, just one fully bonded waterproof layer.
How we work
- 1
Instant Estimate
Fill out our cost estimate tool to receive a fast, ballpark price based on your project details. It's a quick way to understand likely costs before moving forward.
- 2
Site Visit + Detailed Quote
We carry out a site visit where needed to assess your roof in detail, then provide a clear, itemised quote with no hidden costs so you know exactly what to expect.
- 3
Installation
Our trained team prepares the surface and installs the Ultraflex system, delivering a seamless, fully bonded waterproof finish built to last.
- 4
Sign-off & 20 Year Guarantee
We inspect the roof, hand over your 20-year guarantee documentation, and leave the property spotless.
Useful guides
- Flat roof replacement cost in the UK: what drives the price and what a quote should include
- What's included in a roof survey: not sure what you need? Start with a survey
- Commercial flat roofing: for offices, blocks and public-sector buildings
How Ultraflex compares
See how our Ultraflex cold-liquid waterproofing system stacks up against traditional flat roof systems across the things that matter most.
| Criteria | Ultraflex | GRP | EPDM | Asphalt | FeltTorch-on Felt |
|---|---|---|---|---|---|
| Seamless, fully bonded | Yes | Yes | No | No | No |
| Cold-applied (no flame) | Yes | Yes | Yes | No | No |
| Rainproof in 30 minutes | Yes | No | No | No | No |
| Overlay existing roof | Yes | No | No | No | Yes |
| 20-year guarantee | Yes | Yes | Yes | No | Yes |
| Cost-effective long-term | Yes | No | Yes | No | No |
| Resists cracking & shrinking | Yes | No | Yes | No | No |
| Suitable for complex detailing | Yes | Yes | No | No | No |
Because Ultraflex overlays your existing roof, replacement projects typically come in significantly cheaper than a full strip-out. Get an instant estimate using our online tool.
Ultraflex FAQs
The most common questions we get asked about the Ultraflex cold-liquid waterproofing system.
Services tailored to your flat roof, we work on any job.
From new installations and full system refurbishments to targeted leak diagnostics and repairs, every project is carried out by our in-house specialists using premium, manufacturer-approved liquid waterproofing systems.