Home›Flat Roof Waterproofing
Stop a leaking flat roof for good with a seamless, cold-applied GacoFlex coating over your existing roof — no tear-off, no disruption.
Homeowners, landlords, tenants and facilities managers: get free expert advice and a fixed-price quote. Duratite surveys and specifies the system, then matches you with an approved contractor from our Ireland-wide network — backed by a 20-year manufacturer-backed product warranty.
Liquid flat roof waterproofing is a cold-applied coating brushed, rolled or sprayed straight onto your existing roof. It cures into a seamless, fully-bonded membrane with no laps, joints or mechanical fixings — sealing exactly the points where flat roofs leak. GacoFlex systems bond to felt, asphalt, concrete, GRP, single-ply and EPDM substrates, so there is usually no tear-off, no waste skips and no need to move out while the work is done.
A proper survey separates local detail failures from whole-surface breakdown — so the specification fixes the right problem instead of patching over it.
Repeated patch repairs usually mean water is tracking from vulnerable details — laps, upstands, penetrations — not one obvious hole.
Low falls, blocked outlets and ageing surfaces leave standing water that stresses and softens a traditional membrane over time.
Flat roofs expand and contract with heat, slowly opening old cracks, laps and transitions until they let water in.
Sunlight makes felt, asphalt and old coatings brittle and cracked — a whole-surface problem that patching cannot solve.
Most flat-roof leaks come from failed details and a tired surface — not a failed structure. Where the deck is sound and the substrate is suitable for overlay, a GacoFlex liquid coating restores the roof in place: the old covering stays, the leaks are sealed, and you avoid the cost, mess and waste of stripping back to the deck.
GacoFlex bonds directly to most existing flat roofs. The free survey confirms the cleaning, repair, bleed-blocking and primer route for your substrate before any coating goes down.
Cleaned, repaired and, where bitumen bleed is a risk, isolated with A4271 Bleed Trap before coating.
Surface assessed for adhesion; loose granules and blisters made good before the silicone membrane.
Age, cracking and adhesion checked; a bleed-trap base coat isolates staining risk before overlay.
Compatibility and primer confirmed so a silicone coating bonds to and re-seals ageing rubber roofs.
Compatibility, keying and primer selection checked before a seamless coating is applied over the GRP.
Membrane type and primer requirements confirmed before any coating system is specified.
Defect repair, moisture assessment and primer route agreed before the liquid membrane is applied.
Sound silicone-coated roofs can be cleaned, inspected and recoated at end of life — no tear-off.
Duratite specifies both GacoFlex routes. The right one depends on your roof’s drainage, detail risk and whether the surface will be walked on — confirmed on a free survey.
A premium 100% silicone membrane and the go-to route for flat & low-slope roofs — especially where ponding water and UV exposure are the problem. Built around Gaco S42, with SF42 fibre-reinforced seam seal at laps and details.
A heavy-duty two-coat urethane system for flat roofs that get walked on — balconies, walkways, terraces and plant decks. U91 high-build base plus U92 aliphatic top coat give a tough, foot-traffic-rated finish.
A warrantied flat roof relies on more than the field coat — the detail products decide whether it lasts.
Specialist cleaning solution that removes dirt, algae, moss and contaminants — ensuring maximum adhesion of the silicone coating.
Fibre-reinforced silicone seam sealant for laps, upstands, penetrations and detail areas. It is fibre-reinforced, so no separate scrim or mesh is needed.
Flashing-grade instant-cure silicone for cracks, penetrations, rain collars and point repairs — can be applied in wet or dry conditions.
Both are GacoFlex, both are cold-applied and both carry a 20-year warranty — but they solve different problems. We confirm the right fit on a free survey.
| Compare the system | RECOMMENDEDSilicone — Gaco S42Flat & low-slope · ponding | Urethane — U91/U92Walk-on · trafficked |
|---|---|---|
| Best suited to | Flat roofs with ponding — felt, asphalt, concrete, single-ply | Balconies, walkways, terraces & plant decks that are walked on |
| Ponding water resistance | Excellent | Very good |
| UV / weather resistance | Outstanding | Outstanding U92 aliphatic top coat |
| Foot-traffic durability | Limited | Walk-on rated |
| Reflective / cool finish | High (white) | Standard |
| Application | Single coat, cold-applied | 2-coat (base + top), cold-applied |
| Recoatable at end of life | Yes silicone-on-silicone | Yes recoat with U92 |
| Manufacturer warranty | Up to 20 yrs | Up to 20 yrs |
| Relative cost | Lower | Higher |
Felt, EPDM rubber and GRP all have their place — especially on new builds. For refurbishing an existing flat roof, a liquid silicone overlay is usually faster, cleaner and cheaper. Here they are side by side, using publicly available data.
| Compare the systems | RECOMMENDEDGacoFlex S42Silicone · liquid overlay | Felt / torch-onBuilt-up bitumen | EPDM rubberSingle-ply sheet | GRP / fibreglassGlass fibre + resin |
|---|---|---|---|---|
| System type | 100% silicone, seamless liquid | Built-up bitumen sheets, hot-laid | Single rubber sheet, bonded | Glass fibre matting + resin, wet-laid |
| Install over existing roof | Yes — overlay, no tear-off | Usually strip & re-lay | Usually strip to deck | Strip to deck / new board |
| Seams & joints | Seamless — none to fail | Lapped seams (common leak point) | Bonded / taped seams | Jointless but rigid — can crack |
| Ponding water | Rated for permanent ponding | Poor under standing water | Tolerant with good falls | Tolerant but brittle with age |
| Hot works / fire risk | None — cold-applied | Naked flame (torch-on) | Cold (adhesive) | Cold — styrene fumes / cure |
| Warranty | Up to 20-yr manufacturer-backed | 10–20 yr | 20+ yr | 20–25 yr |
| Disruption | Low — over the live roof | High — strip & hot works | High — strip to deck | High — strip, cure, weather-sensitive |
| Best for | Refurbishing existing flat roofs; ponding; detail-heavy roofs | Budget new-build flat roofs | Simple rectangular new roofs | Small new balconies & roofs |
GacoFlex silicone and walk-on urethane flat roof waterproofing is priced per roof — applied without a tear-off, it typically costs a fraction of full replacement. Every quote is fixed-price after a free survey.
| Flat roof size | RECOMMENDEDGacoFlex coating costFully installed | Full replacement | Saving |
|---|---|---|---|
| 20 m² (small extension) | Fixed price after survey | Strip-out, disposal & new roof | 60–80% |
| 50 m² (garage / bay) | Fixed price after survey | Strip-out, disposal & new roof | 60–80% |
| 100 m² (house / terrace) | Fixed price after survey | Strip-out, disposal & new roof | 60–80% |
| 250 m²+ (block / commercial) | Fixed price after survey | Strip-out, disposal & new roof | 65–80% |
Most flat-roof leaks come from failed details and a tired surface — not a failed structure. Where the deck is sound and the substrate is suitable for overlay, the old covering stays, the leaks are sealed, and you avoid the cost, mess and waste of stripping back to the deck.
No skips, no exposed deck, no weather risk, and you stay in the building while the work is done.
At end of life a silicone roof is cleaned, inspected and recoated — silicone on silicone, still no tear-off. That is what makes the whole-life cost so different from a strip-and-replace cycle.
The journey from a leaking, ponding asphalt roof to a seamless silicone membrane — with the old covering still in place underneath.
Genuine GacoFlex flat-roof projects — the building, the problem, the system and the watertight result.
A tired asphalt flat roof restored with A4271 Bleed Trap and GacoFlex S42 silicone — no tear-off.
A terrace flat roof sealed around parapet walls with SF42 and coated with GacoFlex silicone.
A residential flat roof upgraded and waterproofed with a warm-roof build-up and GacoFlex coating.
Looking for a GacoFlex-approved installer? GacoFlex silicone only performs when it is specified and applied correctly — so tell us your roof and Eircode (or postcode in Northern Ireland), and Duratite matches you with a vetted, trained, Duratite-approved installer from our Ireland-wide network, with the right system specified for your roof.
Matched to your roof & locationWe pick the installer from the network that suits the job and the location.
Vetted, trained applicatorsEvery installer is vetted and trained on the GacoFlex system before they are put in front of a customer.
The correct GacoFlex spec, first timeDuratite surveys and specifies, so the installer works to a written specification rather than a guess.
20-year manufacturer-backed warrantyThe product warranty is issued by the manufacturer; the installation is carried out by the approved contractor.
We’re your single point of contact: Duratite surveys and specifies the system, then matches you with a vetted contractor from our Ireland-wide approved network to carry out the work.
Send the roof type, area, leak history and a few photos of your flat roof.
Substrate, ponding, upstands, drainage and access assessed — and whether overlay is suitable.
Silicone or urethane system, detailing and primer — at a fixed, fully installed price.
A vetted contractor from our approved network cold-applies the system — no tear-off, roof stays in use.
20-year manufacturer-backed product warranty and documentation.
Send the roof type, size and a few photos and we’ll book your free survey. For an active leak, GacoPatch gives an instant-cure repair — even in the wet — while we plan the full coating.
Straight answers on cost, lifespan, ponding water, substrates, systems, tear-off and warranties. Can’t see yours? Ask us directly and we’ll come back to you the same working day.
Encapsulate and weatherproof asbestos-cement roofs with Gaco silicone — no intrusive removal.
Learn more →ProductProduct information for the 100% silicone roof coating at the heart of the flat-roof system.
Learn more →RangeThe full GacoFlex range — S42 silicone, U9 urethane, SF42 seam seal and detailing products.
Learn more →CommercialSilicone, acrylic and urethane systems for commercial and industrial roofs across Ireland and Northern Ireland.
Learn more →OverlayExtend the life of a tired flat roof at a fraction of replacement cost.
Learn more →Leak nowActive leak? Stop it fast, without a strip-out or full roof replacement.
Learn more →Tell us about your flat roof — type, approximate size and the problem. We survey it free, design the right GacoFlex system and issue a fixed quote with a 20-year manufacturer-backed warranty.
Prefer to talk? Email info@duratite.ie — Mon–Fri, 8am–5pm.
Mon–Fri 8am–5pm · info@duratite.ie
Free survey and fixed written specification in every county, installed through our approved installer network. Choose your area.
Tell us about your building and we’ll recommend the right system — foam, waterproofing or both — surveyed, specified and quoted at no cost.
