Flat Roof Replacement
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.
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.
Drag the slider to see the transformation
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 - fully bonded, seamless and rainproof in 30 minutes - for 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, 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 - a fully bonded waterproof layer.
How we work:
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.
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.
Installation
Our trained team prepares the surface and installs the Ultraflex system, delivering a seamless, fully bonded waterproof finish built to last.
Sign-off & 20 Year Guarantee
We inspect the roof, hand over your 20-year guarantee documentation, and leave the property spotless.
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 | Torch-on Felt |
|---|---|---|---|---|---|
| Seamless, fully bonded | |||||
| Cold-applied (no flame) | |||||
| Rainproof in 30 minutes | |||||
| Overlay existing roof | |||||
| 20-year guarantee | |||||
| Cost-effective long-term | |||||
| Resists cracking & shrinking | |||||
| Suitable for complex detailing |
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.
Why Ultraflex — FAQs
The most common questions we get asked about the Ultraflex cold-liquid waterproofing system.
What is Ultraflex cold liquid-applied waterproofing?
Ultraflex is a cold liquid-applied waterproofing system that uses seamless PMMA resin membranes. It cures quickly, can be applied in low temperatures, and requires no flame or hot works during installation.
What are the benefits of Ultraflex for roofs and terraces?
Ultraflex offers ultra-rapid curing (rainproof in as little as 30 minutes), application in low temperatures (down to 0°C, and -5°C on details), zero-flame installation, resistance to ponding water, long-term durability and a wide range of surfacing options.
How quickly do Ultraflex systems cure, and can they be installed in cold weather?
Ultraflex systems cure rapidly - in some cases within around 30 minutes. They're designed to be applied in low ambient temperatures, down to 0°C on main areas and to -5°C on details.
Do Ultraflex waterproofing membranes need flame or hot works during installation?
No. Ultraflex cold liquid systems are flame-free and don't require any hot works. This dramatically reduces fire and safety risk on site and simplifies compliance, especially on occupied buildings.
Can Ultraflex be installed over my existing roof?
Yes. Ultraflex bonds directly to most existing substrates - felt, asphalt, bitumen, concrete, EPDM, single-ply, GRP and more - so we can overlay your existing roof instead of stripping it out, saving you up to 50% in cost and disruption.
What makes Ultraflex longer lasting and lower maintenance?
Seamless fully bonded waterproofing, excellent resistance to standing water, rapid curing that minimises weather exposure during installation, solvent and isocyanate free resin formulations, and a proven 20-year track record all combine to reduce ongoing maintenance and repairs.
How long does Ultraflex roofing last and what guarantees are offered?
Ultraflex waterproofing systems typically come with a 20-year materials and workmanship guarantee when installed by an authorised contractor like Perlini.
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.
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