Applications
Refurbishment for every flat roof type
Instead of stripping the roof, HYDRONYLON® is applied as an overlay on the existing covering: felt, metal, concrete or PVC membrane. Find your roof type below to see the exact build-up.
Bituminous felt
Bituminous felt is the most common flat roof type in the UK. Aged felt cracks in UV, laps open, blisters form and ponding water speeds all of it up, so a leaking felt roof rarely stays fixed with patches.
Build-up, layer by layer
- HYDRONYLON HP base, minimum two coats, minimum 2.0 kg/m² in total
- Technical Mesh SW-1 embedded into the second coat, overlaps at least 10 cm
- HYDRONYLON HN top coat at 0.8 to 1.0 kg/m²
System materials cost: £34.89/m² (materials only)
Metal
Profiled and standing seam metal roofs fail at the details: corroding sheets, loosened fixings and leaking seams and laps. Metal roof waterproofing with a liquid system seals all of them in one continuous layer.
Build-up, layer by layer
System materials cost: £16.39/m² (materials only)
Mineral and concrete
Concrete and screed decks are porous and crack with thermal movement, so water finds a path through hairline cracks and failed patch repairs. Concrete flat roof waterproofing needs a primed, fully bonded build-up.
Build-up, layer by layer
System materials cost: £18.48/m² (materials only)
PVC membrane
PVC membranes turn brittle with age, welds and seams open and mechanical damage exposes the deck. PVC roof membrane repair with the liquid system overlays the whole surface instead of chasing individual welds.
Build-up, layer by layer
- HYDRONYLON HN, minimum 2.2 kg/m² in at least two coats, the first worked in by brush through Technical Mesh SW-1 with overlaps of at least 5 cm
- Technical Mesh SW-1 reinforcement across the full surface
System materials cost: £32.61/m² (materials only)
Need help?
Not sure what your roof is?
Most flat roofs are one of the four types above, but mixed and patched roofs are common. A photo of your roof sent by email is enough for an initial assessment.
The comparison
Refurbish vs replace
| Refurbish with HYDRONYLON | Full replacement | |
|---|---|---|
| Time on the roof | Days | Weeks |
| Existing covering | Stays in place | Stripped and sent to landfill |
| Hot works | None, cold applied | Often required |
| Disruption | Low: no strip-off, no skips, building stays in use | High: strip-off, waste removal, exposure to weather |
| Guarantee | 10-year product guarantee issued to the Approved Contractor | Varies |
FAQ
Frequently asked questions
Can you waterproof over an old felt roof without removing it?
Yes, provided the existing felt is sound, which a survey confirms. The build-up goes straight over it: HYDRONYLON HP in a minimum of two coats, Technical Mesh SW-1 reinforcement and the HYDRONYLON HN top coat. See the felt build-up above for the full specification.
How long does the work take?
Days rather than weeks. Each coat cures for at least 24 hours before the next, so a typical two- or three-layer build-up spans a few site days, weather permitting. There is no strip-off phase, which is where full replacement loses most of its time.
What happens to ponding water areas?
Ponding areas are identified in the survey and made good during preparation, so the liquid layers are applied to a sound, dry surface. The cured system is assessed watertight under ETA-23/0735 and tolerates surface temperatures from -20°C to +80°C.
Does it work on roofs with many penetrations and details?
Yes, this is where a liquid-applied system is strongest. The liquid forms in place around outlets, rooflights, upstands and pipework, and Technical Mesh SW-1 reinforces every detail, with no cutting and patching of sheet material.
What does it cost?
The cost depends on the condition of the roof, its area and the amount of detailing, so every project is priced individually after a survey. Refurbishment is typically significantly more economical than a full re-roof because the existing covering stays in place. For a fuller breakdown, see how much flat roof refurbishment costs. For a quotation, speak to an Approved Contractor or contact us directly.