PETG sheet flammability is an HB story, and HB is not a fire rating. The question comes late in a project, usually from a safety reviewer: the display looks right, the cost is right, and then someone asks for the fire rating. The answer for standard PETG is HB, and that answer sometimes ends the discussion.
PETG sheet flammability is worth understanding before the design is fixed, because the material choice is easy to change early and expensive to change after tooling.
PETG sheet flammability: what the ratings mean
- UL94 HB: horizontal burn, slow spread, the typical PETG result
- UL94 V-2: vertical burn, self-extinguishing within 30 s, dripping allowed
- UL94 V-0: vertical burn, self-extinguishing within 10 s, no dripping
- Assembly rating: the finished construction, not the sheet alone
HB is a horizontal test. A sample is held flat and ignited, and the burn rate must stay below a threshold. It tells you the material will not flash across a surface. It tells you nothing about how a vertical panel behaves in a real fire, which is why V ratings exist and why PETG does not carry them.
Suppliers sometimes describe PETG as self-extinguishing because the flame goes out when the source is removed. That is true of many thermoplastics and is not a rating. Ask for the test report and the classification, not an adjective.
Where the material question has to change
Three situations should push a project off PETG: an enclosure around mains voltage, a panel in an egress route, and any specification that names V-0 or a building class. In each case the answer is a different plastic, not a thicker PETG sheet.
Where PETG is genuinely fine: retail display, signage faces, packaging, machine covers away from heat, and decorative panels in sprinkler-protected spaces where the authority has accepted an HB material.
One more distinction buyers miss: a material rating is not an assembly rating. A V-0 sheet in an untested frame with a combustible gasket is not a V-0 assembly. If the project needs a rated construction, the whole build-up has to be tested together. The flame retardant acrylic and PC UL94 guide explains how the rated grades differ, and the PC UL94 guide covers the polycarbonate options.
For projects where PETG stays, the processing notes in our thermoforming guide include the temperatures at which the sheet is most vulnerable to ignition.
Tell us the fire specification for your project at oversales@rpplexiglass.com and we will confirm what PETG can and cannot claim.
Frequently Asked Questions
Is PETG fire retardant?
Standard PETG is not. It typically achieves UL94 HB, which means it burns slowly across a horizontal sample. It is not V-0, V-1 or V-2, and it should not be specified where a vertical burn rating is required.
What does UL94 HB mean in practice?
A horizontal test where the burn rate stays under a set limit. HB is the lowest classification and indicates a material that will burn but slowly. It gives no protection in a vertical fire scenario.
Can PETG be used in an electrical enclosure?
Only where the enclosure standard allows an HB material and the design provides separation from heat sources. Most mains-voltage enclosures require a V-rated plastic, and PETG is the wrong choice there.