PTFE-Coated Fibreglass Membrane

How it is built up

Fine continuous glass filaments are twisted into yarns and woven into a base cloth. The cloth is then drawn repeatedly through a PTFE dispersion and sintered at high temperature after each pass, so the coating fuses into a continuous film that encapsulates every fibre. The number of coats and the base-cloth weight set the grade.

What each part does

The glass weave carries all the tension — it is strong, dimensionally stable and does not creep or degrade under UV. The PTFE film does no structural work: it seals the glass against water and abrasion, gives the surface its very low friction (hence the self-cleaning) and its chemical inertness, and provides the fire performance.

Why it is not just "a better PVC fabric"

PVC-coated polyester uses a flexible polyester weave and a soft PVC coat — it folds, takes colour and welds easily. PTFE-glass uses a stiff, brittle mineral weave and a hard fluoropolymer film — it cannot be sharply folded, comes in white only, and needs specialist welding, but it lasts far longer and will not burn.

Physical characteristics (typical, standard grade)

Total coated weight

~800–1,600 g/m² by grade; ~1,100 g/m² is a common standard

Thickness

~0.6–1.0 mm (grade-dependent)

Tensile strength (strip)

Standard grade around 3,500–7,000 N/5cm warp & weft; higher grades more — manufacturer specified

Light transmission

~7–20% by grade; commonly ~12–17%, fully diffused

Solar reflectance

~70–75% for a clean white surface

Reaction to fire

EN 13501-1 A2-s1,d0 (non-combustible); passes NFPA 701; no melting, no flaming droplets — verify the exact product

Design service life

Commonly quoted 25–30+ years; the earliest PTFE roofs are now 40–50+ years old and in service

Ranges are typical industry figures for the material class. Actual values come from the datasheet for the specific product and grade, confirmed against the project’s structural and fire requirements.

Fire — A2, non-combustible

Both the glass base and the PTFE film are non-combustible. Products are typically classified EN 13501-1 A2-s1,d0 and pass NFPA 701: the membrane does not ignite, does not melt, adds no fuel to a fire and produces no flaming droplets. This is the reason PTFE-glass is specified for assembly occupancies, escape routes and buildings whose codes demand a non-combustible reaction — where PVC, PVDF and ETFE (all B-class, self-extinguishing) are not accepted. Always verify the exact product classification against the project’s fire strategy.

Light & night appearance

PTFE-glass transmits roughly 7–20% of daylight depending on grade — commonly around 12–17% — and diffuses all of it, so the interior is evenly lit and shadow-free with no view of the sky. At night, uplighting the membrane makes the whole roof glow, which is often part of the architecture.

Solar & thermal

A clean white PTFE surface reflects about 70–75% of incident solar energy and absorbs very little, so an uninsulated PTFE roof runs cool and re-radiates little heat downward — useful in hot climates. It is still a single membrane: for a controlled U-value in a heated or cooled building, an insulated or lined build-up is used, which trades away some translucency. Low-emissivity grades reduce radiant gain further.

Weather, UV & self-cleaning

PTFE is chemically inert and essentially unaffected by UV, ozone, pollution and salt air — the surface chemistry that limits PVC does not apply. The low-friction surface is hydrophobic, so rain lifts and carries away most airborne dirt and the roof stays white with little intervention. Decades of installed roofs in a wide range of climates support the long-life claims.

Acoustics

Like all single membranes, PTFE-glass has low mass and gives little sound insulation; rain on a taut roof is audible and large volumes can be reverberant. Where acoustics matter, an acoustic build-up (liner plus absorption) or room design — not the membrane alone — is the answer.

Durability & real service life

Manufacturers quote 25–30 years and more; the earliest PTFE-glass roofs, from the 1970s, are 40–50+ years old and still in service. In practice the membrane rarely sets the life of the roof — handling damage, seam condition, connections and the supporting structure usually do. Any lifespan figure should be tied to a named product, a specification and an exposure.

Trade-offs — stated plainly

White only, no pigmented colour. Brittle glass base — no sharp folds, careful handling, higher logistics cost. Highest material and fabrication cost of the common membranes. Longer lead times. Not an acoustic or an insulation solution on its own.