TPO, PVC and EPDM Systems
We install single-ply membranes that are heat-welded or adhered into one continuous watertight layer, ideal for flat and low-slope roofs on commercial and residential buildings, for Wellington homeowners and businesses.
Wellington Membrane Roofing
Choosing the Right Membrane for a Flat Roof or Deck Membrane Roofing
Membrane Roofing in Wellington
A membrane roof is a continuous waterproof sheet laid over a flat or low-pitch roof instead of overlapping sheets or tiles. You'll find membrane roofing in Wellington on 1970s flat-roofed houses, villa lean-tos, decks over living areas, box gutters and most commercial buildings. When it is right, it is one of the most watertight roofs you can have. When the seams, falls or substrate are wrong, water finds its way in quietly and spreads before anyone notices.
There is no single best membrane. TPO, PVC, EPDM, torch-on bitumen and butynol each have their own seam method, substrate needs and typical uses. We help you choose the one that suits the roof, how it will be used and how exposed it is, then install it with properly formed outlets, upstands and edges. We also repair split seams, blisters and failed outlets on existing membrane roofs.
Membrane Roofing
Membrane Roofing Services in Wellington
Torch-On and Butynol Options
Traditional torch-on and butynol membranes remain reliable, cost-effective choices. We recommend the right product for your roof's size, access and use, installing it to manufacturer specifications, with honest practical advice.
Membrane Repairs and Recovering
Blistered, split or aged membranes can often be repaired or recovered without full replacement. We assess condition honestly and recommend the most economical option for your situation, from day one.
Membrane Roofing
The Main Membrane Types Compared
The biggest practical difference between membranes is how the seams are made, because the seams are where leaks start. Rubber membranes are bonded with adhesives and tapes, thermoplastics are welded with heat, and bitumen is fused with a flame or self-adhesive layer.
Butynol (butyl rubber)
A synthetic rubber sheet used on New Zealand flat roofs and gutters for decades. Laps are bonded with adhesive or joining tape over a plywood substrate. Flexible, tolerant of small movement and repairable as it ages.
EPDM
Another synthetic rubber, supplied in large sheets that reduce the number of seams. Seams are made with primers and tapes rather than heat. Good UV resistance and flexibility make it a common choice for larger residential roofs and green roofs.
TPO
A thermoplastic sheet whose seams are fused with hot air, so the joint becomes one piece of material. Usually white or light grey, which reflects heat. Common on commercial roofs and increasingly used on houses.
PVC
Also heat-welded, with strong seams and good resistance to oils and grease, which suits some commercial and hospitality roofs. Pre-formed corners and pipe boots weld straight in, making penetration details neat.
Torch-on bitumen
Modified bitumen sheets, usually laid in two layers and bonded by melting the underside with a gas torch. Tough and puncture resistant under foot traffic, but open flame near timber needs strict fire precautions or a self-adhesive alternative.
Liquid-applied membranes
Applied as a liquid in several coats, often with a reinforcing fleece, curing to a seamless skin. Useful around crowded penetrations and awkward details on small roofs. It needs dry weather and careful control of film thickness to perform.
Membrane Roofing
Seams, Substrates and Falls
Most membrane failures start at a seam, an edge or an outlet rather than in the middle of the sheet. Heat-welded TPO and PVC seams are probed along their length once they cool. Glued and taped rubber seams need clean, primed surfaces and enough overlap, and they are pressed down firmly with a roller. On every system, upstands at walls, parapets and door thresholds are taken high enough to stay above splash and ponding.
The substrate matters as much as the membrane. Most residential membranes go over plywood laid with tight, supported joints, so the sheet does not crease or split over a gap. The roof also needs enough fall to drain, with sound outlets and overflows, as Building Code clause E2 requires. Ponding water on a flat roof is a design fault, not a quirk, and we correct the falls before laying new membrane.
Membrane Roofing
Where Each Membrane Works Best
Butynol and EPDM suit residential flat roofs, small decks, box gutters and awkward shapes, because rubber is easy to dress around corners and repair later. TPO and PVC suit larger, simpler roofs and commercial buildings, where long welded seams and reflective surfaces pay off. Torch-on suits roofs that take regular foot traffic or carry plant and equipment.
Decks over living spaces are a special case. The membrane is hidden under tiles or timber, so a leak is hard to trace and expensive to reach. We protect the membrane from point loads with pedestals or a protection layer and detail door thresholds with extra care. For a wider look at low-slope options, see flat roofing, and for membranes in gutters, see box gutters.
Membrane Roofing
Membrane Repairs We Handle
Not every leaking membrane needs replacing. We find the actual source first, then choose a repair compatible with the existing material.
Split and lifted seams
Old butynol and EPDM seams can lift as the adhesive ages. We clean, prime and re-bond them, or cover them with a compatible seam strip, which can often stop a leak without replacing the whole roof.
Blisters and bubbles
Trapped moisture or air under torch-on and some adhered membranes forms blisters. Small, stable ones are monitored, while split ones are cut, dried and patched. Lots of blisters point to moisture in the substrate, which we investigate.
Blocked or failed outlets
Outlets clog with leaves, and the membrane joint around an outlet is a common leak point. We clear, re-form or replace outlets and add overflows where the roof has none, so a blockage can't flood the building.
Punctures and wind damage
Dropped tools, aerial installers and Wellington gusts lifting unsecured edges all damage membranes. We patch with compatible material and re-secure edges and termination bars. See roof leak detection and repair.
Upstands pulled away from walls
Where a membrane turns up a wall or parapet, the adhesive can fail and the upstand slumps, letting water in behind cladding. We re-form and re-bond upstands, then protect the top edge with a termination bar or capping.
Crazed and weathered surfaces
Years of UV leave some membranes crazed, chalky or brittle on the surface. Where the sheet is still sound and well bonded, a compatible coating can extend its life. See roof coating and sealing.
Membrane Roofing
Why Choose Our Membrane Roofing Contractors in Wellington
Membrane roofs are only as good as their joins, upstands and drainage details, so we give each one careful attention. Our contractors install TPO, PVC, EPDM, torch-on and butynol systems, and we will recommend the product that best suits your roof size, access and use. Seams are welded or adhered precisely, penetrations are sealed correctly, and falls are checked so water drains rather than ponds. If your existing membrane is blistered, split or ageing, we assess it honestly and tell you whether repair, recovering or replacement offers the best value. Every installation follows manufacturer specifications, giving you a continuous, watertight surface and reliable, long-term protection. Call us for a clear, honest quote.
- Experienced with all major membrane systems
- Precisely welded or adhered seams
- Correct sealing around penetrations
- Honest repair, recover or replace advice
- Installed strictly to manufacturer specifications
Membrane Roofing
Related Services
Membrane work often connects with these services, from waterproofing decks and gutters to designing a new flat roof or a living roof.
Helpful answers
Membrane Roofing FAQs
Call our team if you need advice for your property or roofing project.
04 888 0115What is the difference between TPO and EPDM?
Both are single-ply membranes, but they are joined differently. TPO is a thermoplastic, so its seams are welded with hot air into a single piece of material. EPDM is a synthetic rubber, and its seams are bonded with primer and seam tape. TPO is often light-coloured and reflective, while EPDM is usually black and very flexible. Either can perform well when the seams and details are done properly.
Is butynol still a good choice for a flat roof?
For many residential roofs, yes. Butynol is flexible, handles small movement in timber framing, dresses neatly into box gutters and around upstands, and is easy to repair. It needs a sound, smooth plywood substrate and well-bonded laps. On large, simple roofs a welded membrane may be quicker to install with fewer seams.
Can a new membrane go over my old one?
Sometimes, if the old membrane is well adhered, compatible with the new one and the substrate underneath is dry. In practice, many older Wellington flat roofs have water trapped in the plywood, and covering that over seals the problem in. We usually strip back, check and replace damaged plywood, and correct the falls before laying new membrane.
Why is water ponding on my flat roof?
Common causes are not enough fall, plywood that has sagged between joists, outlets set too high, or outlets blocked with leaves. Ponding loads the structure, holds water on seams and speeds up wear. We fix the cause, whether that means packing up the framing to create proper falls, relocating outlets or adding overflows.
Is torch-on safe to install on a timber house?
Torch-on uses an open flame, so fire risk on timber buildings is real. Safe practice includes keeping the flame away from timber edges and gaps, using self-adhesive base sheets in sensitive areas, having extinguishers on hand and watching the roof after work finishes. On some roofs we recommend a different membrane rather than taking the risk.
Wellington Roofing
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