Single Ply Flat Roof Alternative
Single-ply membranes are popular for new builds, but they puncture easily and rely on seams that can open over time. We install Ultraflex over single-ply and other existing roofs, creating a seamless, fully bonded waterproof layer with no joints and a 20-year guarantee.
The problems with single ply flat roofs
Single-ply roofs are thin, flexible membranes that waterproof through sheet coverage and sealed joints. That makes them vulnerable to punctures, seam failure and weather damage.
Small holes from stones and grit
Foot traffic, wind-blown gravel, and maintenance work easily puncture the thin membrane. Even small holes let water in and are hard to locate.
Joints can open
Seams and laps are sealed with tape or heat welding. Over time these joints can open, peel or lift, creating direct leak paths across the roof.
Shrinkage and stress
Single-ply membranes can shrink, pulling away from upstands, drains and edge details and stressing the sealed joints.
Poor detailing around penetrations
Rooflights, pipes, corners and upstands need careful flashing. Every detail is a potential failure point when the sheet is cut and sealed.
UV and weather damage
Sun exposure and ponding water degrade the surface, reducing flexibility and making the membrane more brittle and puncture-prone over time.
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Why we install our waterproofing system over single ply
Single-ply roofs are vulnerable to punctures from stones and grit, and their seams can open as the membrane ages. Our waterproofing system is a seamless, fully bonded liquid membrane with no joints to fail, and it can be applied directly over an existing single-ply roof - backed by a 20-year guarantee.
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 |
Ultraflex over an existing single-ply roof avoids the cost of a full strip-out and removes the risk of punctures and open seams. Use our estimator for a personalised quote.
Why Ultraflex — FAQs
The most common questions we get asked about the Ultraflex cold-liquid waterproofing system.
How long does a single ply roof last?
Manufacturers typically offer twenty to twenty five year guarantees, and the sheet material can achieve that. Whether a particular roof does depends on the quality of the hot air welding, the amount of foot traffic it receives, the number of penetrations, and whether small punctures are found and repaired before water reaches the insulation.
Can you waterproof over an existing single ply membrane?
Yes, provided the insulation below is dry and the membrane is still adhered or fixed soundly. After cleaning, adhesion testing and priming for PVC or TPO, the liquid system is applied over the whole roof, sealing the existing welds, fixings and details under one seamless membrane.
How do you find a leak in a single ply roof?
It is genuinely difficult, because water entering a puncture can travel a long way through the insulation before it shows inside. We survey the roof surface systematically, check every weld, fixing and detail, and use moisture readings to map where water has spread. This is exactly the problem a fully bonded membrane removes for the future.
Why does single ply get punctured so easily?
The sheet is only a millimetre and a half to two millimetres thick and it sits over compressible insulation, so any point load concentrates on a very small area. Grit under a boot, a dropped fixing, ladder feet and scaffold boards are the usual culprits, and roofs with plant or solar panels that need regular access accumulate damage fastest.
Is this suitable for a large commercial roof?
Yes. Cold liquid overlays are widely used on commercial and public buildings precisely because they avoid hot works, avoid a strip-out, and let the building stay in use throughout. We have applied the system on hospital, high-rise and commercial roofs across London and can phase the work to suit access restrictions.
What happens to the existing mechanical fixings?
They stay where they are and keep doing their structural job of holding the build-up down. The new membrane goes over the top of them and over their welded patches, so the fixing heads are no longer a point at which the waterproofing is penetrated.
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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