Services / Torch-on Felt Roofing

    Torch-on Felt Roof Alternative

    Torch-on felt roofs require the use of naked flames during installation and rely on multiple lapped joints. We overlay your existing roof with Ultraflex, a cold-applied waterproofing system that bonds directly to felt, eliminates hot works on site, and provides a seamless waterproof membrane backed by a 20-year guarantee.

    • Cracks, blisters and bubbles
    • Leaks at the laps
    • Hot works on site
    • Short lifespan
    Instant Estimate
    Common problems

    The problems with torch-on felt roofs

    The quality of torch-on felt roofs varies significantly. During our leak investigations, we regularly encounter low-quality systems that have been poorly installed. Multiple layers of bitumen are flame-bonded on site, resulting in numerous joints, a limited lifespan, and an increased fire risk during installation.

    • Cracks, blisters and bubbles

      Bitumen hardens and shrinks with age and UV, causing surface cracking, blistering and trapped-air bubbles that rupture and leak.

    • Open flame fire risk on install

      Torch-applied felt uses a naked gas flame against the deck and any nearby timbers. It is one of the leading causes of building fires during roofing works.

    • Multi-layer system with weak laps

      Three layers of underlay, intermediate and cap sheet, all bonded at overlapping laps. Every lap is a potential failure point as the bitumen ages.

    • Short lifespan

      Even well-installed felt typically lasts 10-15 years before noticeable failure, far less than modern liquid systems.

    • Weather-driven degradation

      Sun, frost, ponding water and thermal movement all attack the bitumen, leading to brittleness, splits and loss of waterproofing.

    Old torch-on felt flat roof showing cracking, bubbling and weather damage
    Felt vs Perlini System

    Why we install our waterproofing system over felt

    Felt is a short-life material that cracks, bubbles and shrinks within years, and torch-on installation introduces a real fire risk to your property. Our waterproofing system is cold-applied with no flame, bonds directly over your existing felt, and delivers a seamless 20-year waterproof layer for a fraction of the cost of a full strip-out.

    Same roof overlaid with seamless Ultraflex membrane
    Old felt flat roof showing cracks, bubbling and worn bitumen
    BeforeAfter
    Powered by Ultraflex

    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.

    Ultraflex flat roof installation

    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. 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. 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. 3

      Installation

      Our trained team prepares the surface and installs the Ultraflex system, delivering a seamless, fully bonded waterproof finish built to last.

    4. 4

      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.

    CriteriaUltraflexGRPEPDMAsphaltFelt
    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

    Ultraflex over existing felt is typically up to 50% cheaper than a strip-and-replace job, and lasts far longer. Use our estimator for a quick price.

    Ultraflex FAQs

    The most common questions we get asked about the Ultraflex cold-liquid waterproofing system.

    A good three-layer felt roof, properly installed with well-formed laps, will usually give ten to fifteen years, and sometimes twenty on a sheltered roof with good falls. Poorly torched laps, standing water or a south-facing aspect can cut that to well under ten. The mineral cap sheet losing its granules and the laps beginning to lift are the clearest signs the roof is near the end of its service life.

    Yes, in the great majority of cases. Bitumen felt is a substrate the Ultraflex system bonds to well once it has been cleaned, made good and primed. We only recommend stripping where water has already saturated the insulation or damaged the deck, because sealing over wet build-up traps the moisture rather than solving the problem.

    No. The entire system is cold applied by roller and brush. There is no naked flame, no gas bottle on the roof, and no requirement for a hot works permit or a fire watch afterwards, which is one of the main reasons managing agents and schools prefer it on occupied buildings.

    Because the joints are the only part of the roof made by hand on site. The felt sheet itself is a factory-made product of consistent quality, but every lap is welded manually with a torch, and both under-heating and over-heating produce a bond that will fail before the sheet does. As the bitumen hardens with age, thermal movement concentrates stress on exactly those lap lines.

    Not usually, once the full picture is compared. A like-for-like felt replacement includes stripping and disposing of the old covering, which the overlay avoids entirely. The liquid system also lasts considerably longer and carries a twenty-year guarantee, so the cost per year of service life is markedly lower even where the up-front figures are similar.

    The membrane itself is unaffected by standing water, unlike bitumen felt, which degrades where water sits. Where ponding is severe we can also build up falls locally before waterproofing so the water reaches the outlets, and we will always tell you at survey stage whether that work is worth doing on your roof.

    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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