If your garage roof was laid in old bituminous felt, you’ll know the familiar cycle: cracks at the laps, blistering, the odd patch after a storm, and that stubborn ponding that never quite goes away. Modern flat-roofing systems break that cycle. They’re tougher, cleaner to detail, and designed to perform for decades when installed correctly.
At Watkins Flat Roofing, we install advanced single ply membranes and cold applied liquid systems—both excellent choices for garages.
Why replace felt rather than patch it (again)?
Your best-value modern options
Longer service life: Contemporary systems are engineered to resist UV, movement and standing water far better than traditional felts. For example, our single ply membranes are specified for long service lives (30+ years when correctly designed and installed).
Cleaner detailing: Modern materials handle abutments, edges, and penetrations with purpose-made trims and accessories that reduce future leak risk.
Less disruption: Many garage roofs can be refurbished as an overlay when the deck is sound, avoiding a full strip and the mess that comes with it. (Where the deck is rotten or insulation is saturated, we’ll advise a full replacement.)
1) Single ply membranes (EPDM, TPO, PVC)
Single ply is a flexible sheet system installed in large panels, meaning fewer seams and quicker installations on typical garage spans. It offers excellent weathering, low maintenance, and neat terminations into fascias or masonry. We specify different single ply types to suit the job:
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EPDM for simplicity and wide single-piece coverage on small to medium roofs.
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TPO or PVC where heat-welded seams, higher reflectivity or specific chemical resistance are useful (e.g., workshops).
On our site you’ll see single ply positioned as a proven, durable flat roofing technology with long service life—precisely why it’s such a strong upgrade from felt on garages.
2) Cold applied liquid roofing
Cold applied liquids form a seamless, fully bonded waterproof layer that excels on tricky shapes—think corrugated outbuildings, multiple rooflights, or lots of pipework. Because it’s applied without flames, it’s well suited to tight residential settings and overlay refurbishments where the substrate is still sound.
Build-ups that actually last: insulation, falls, and drainage
A durable garage roof isn’t just about the membrane—the build-up matters.
Warm roof upgrade: Adding insulation above the deck helps control condensation in unheated garages and can make adjacent rooms noticeably more comfortable.
Introduce falls: Creating falls (often with tapered insulation) moves water decisively to outlets, reducing ponding and extending the life of the system.
Right outlets, right places: Properly positioned outlets or internal gutters, sized for local rainfall, are a quiet hero of long-term performance.
Overlay or strip-and-replace? How we decide
Every garage is different, so we start with a roof survey and moisture check:
Overlay when the existing deck is dry, stable and well adhered. Single ply or liquid can be installed over a prepared surface with the correct primers and vapour control strategy.
Strip-and-replace when we find widespread saturation, rotten decking, or systemic detailing faults. That’s the moment to correct falls, upgrade insulation and re-detail edges for the long term.
The details that keep water out
Most flat-roof failures begin at the edges and penetrations, not in the middle of the roof. We pay particular attention to:
Parapets and upstands with the correct height and termination.
Edge trims that shed water cleanly into gutters.
Penetrations (vents, cables, brackets) with compatible collars and liquid-detailed transitions.
Drainage maintenance—clear pathways to outlets to prevent ponding from returning.
Lifespan, guarantees and peace of mind
We install systems from recognised manufacturers, with manufacturer-backed guarantees available when installed to specification. Single ply, in particular, is as a long-life solution for modern homes and garages—one of the key reasons customers choose it over felt.
What to expect when you work with us
Free site survey: We inspect the roof, check moisture levels, and advise on overlay vs strip.
Clear specification and quote: You’ll get a written proposal outlining the system, insulation build-up, falls strategy and detailing.
Efficient installation: Most garages are completed swiftly, subject to weather and complexity.
Handover: We provide care guidance and register your guarantee where applicable.
Quick FAQs
Can you overlay my existing felt?
Often, yes—if the substrate is dry and sound. We’ll confirm after a survey.
Do you handle awkward details, like abutting walls and rooflights?
Yes. Single ply accessories and cold applied liquids let us form durable, tidy details around penetrations and upstands.
What about ponding—will it come back?
We design in falls and ensure outlets are correctly positioned. Good drainage is central to long-term performance.
Ready to replace your garage roof?
If your felt roof is letting you down, upgrade to a modern system that’s built to last. Get in touch to arrange a garage roof survey, or read more about our services: Single Ply Membrane, Cold Applied Liquid Roofing, and Flat Roof Repairs.