TPO vs Butynol — Understanding Flat Roof Membrane Systems in New Zealand

Flat Roofs Need More Than Just Roofing — They Need Real Waterproofing

Flat or low-pitch roofs are unforgiving.
They don’t shed water like corrugated iron — they hold it, move it slowly, and rely entirely on the membrane’s integrity.

That’s why products like TPO and Butynol exist — they’re engineered waterproof systems, not just roof coverings.
But while they sound similar, they perform very differently — and installing them properly takes real expertise.

At Aquashield Roofing, we’ve worked with both systems across Horowhenua and the lower North Island — from homes to commercial buildings and internal gutters — and we’ve seen what works (and what fails).

1️⃣ What Is Butynol?

Butynol is a synthetic rubber (EPDM) membrane — flexible, proven, and widely used in NZ for decades.
It’s manufactured by Ardex, and it’s known for:

• Excellent UV resistance
• Long service life (20+ years if maintained)
• Great performance on small or detailed areas

Where Butynol Works Best:

• Smaller flat roofs
• Box gutters and parapets
• Internal gutters or balcony decks
• Complex detailing where flexibility matters

Key Watch-Out:
Butynol installation relies heavily on weather and surface conditions — cold, damp, or dusty surfaces can compromise bonding.
That’s why only trained installers should handle it.

2️⃣ What Is TPO?

TPO (Thermoplastic Polyolefin) is a newer membrane technology — heat-welded rather than glued.
It’s reinforced with scrim for durability and UV stability, and it’s become the global standard for large commercial or modern flat roofs.

Why Builders & Architects Choose TPO:

• Welded seams = watertight joints (no adhesive failure risk)
• Cleaner finish and better resistance to ponding water
• Reflective white surface reduces heat gain
• Low maintenance when installed correctly

Where TPO Shines:

• Large, open flat roofs
• Commercial buildings
• New architectural homes
• Environments needing long-term performance

3️⃣ The Big Difference — Installation Skill & Conditions

Both membranes can perform incredibly well — when installed by professionals who know what they’re doing.
But they also fail fast in the wrong hands.

Butynol requires:

• Precise temperature control during bonding
• Proper priming and curing time
• Skilled detailing at corners, outlets, and laps

TPO requires:

• Specialist equipment (hot-air welders)
• Experience with weld temperature and overlap technique
• Careful substrate prep and edge termination design

These aren’t “learn in a weekend” systems.
They demand planning, clean surfaces, right weather, and real trade experience.

4️⃣ Why Weather Matters So Much

Membrane installation is weather-sensitive — and rushing it never ends well.

• Cold temperatures = poor adhesion (Butynol) and incomplete welds (TPO).
• High humidity = trapped moisture beneath the membrane.
• Strong wind or dust = contamination that weakens bonds.

At Aquashield Roofing, we monitor weather windows carefully — if conditions aren’t right, we wait.
That’s how you get watertight results that actually last.

5️⃣ TPO or Butynol — Which Should You Choose?

It depends on your roof, your design, and your priorities.

The key isn’t the brand — it’s who installs it.

✅ Final Word: Membrane Roofing Is a Craft, Not a Shortcut

Anyone can buy TPO or Butynol — but only trained installers can make them perform the way they’re designed to.
Poor prep or rushed installs lead to leaks that are expensive to trace and fix later.

At Aquashield Roofing, we treat every membrane job like precision work — because that’s what it is.
When we install a TPO or Butynol system, it’s done to manufacturer standards, weather-checked, and built to last decades.

👉 Book a membrane roof inspection — we’ll give you straight advice on whether TPO, Butynol, or a full re-roof is the right solution for your property.