NFPA 701: Flame Propagation of Films
Hanging fabric is one of the few cases of vertically flammable materials in an enclosed area that has been controlled. This means a curtain, banner, or tent wall can offer fire a convenient way up. That is why building codes require flame-propagation performance documentation before any textile material can be used.
MatX Lab performs NFPA 701 testing on drapery fabrics, banners, films, awning and tent materials, and coated textiles.
Two Methods, Split by Areal Density.
The applicable method depends on the material, not preference.
Test Method 1, known as the small-scale test, applies only to materials with an areal density of 700 g/m² (21 oz/yd²) or less. This test is relevant for most interior window coverings such as curtains, drapes, and hanging fabrics. The method specifically excludes vinyl-coated blackout backing, vinyl-coated blackout-backed drapes, plastic films, and non-fabric decorative materials.
Test Method 2, the large-scale test, applies to fabrics and multilayer fabrics above 700 g/m², with or without reinforcement or backing. It is also mandatory, regardless of weight, for vinyl-coated blackout linings and lined draperies using them, for plastic films used decoratively or as temporary building enclosures, and for fabrics used in awnings, tents, tarpaulins, banners, and similar architectural fabric structures.
Sending a vinyl-coated blackout lining for Method 1 is the most common submission error, and the material falls outside that method, regardless of weight.
Test Method 1 Procedure
Cut ten specimens at 150 mm × 400 mm, with the length parallel to the material’s lengthwise direction, and weigh them.
Condition for at least 30 minutes at 105 ± 3 °C. Condition materials that melt or permanently deform at that temperature instead at 20 ± 5 °C for at least 24 hours. Remove each specimen from conditioning individually, attach it to a pin bar, and mount it on a support hanger at the back ceiling of the test chamber.
Apply a specified gas flame for 45 seconds, then remove it and weigh the specimen again once burning has stopped.
Acceptance Criteria
| Criterion | Requirement |
| Average mass loss | 40% or less across the ten specimens |
| Individual specimen mass loss | Investigated where it exceeds the mean plus three standard deviations |
| Afterflame | Any specimen flaming more than 2 seconds after flame removal fails |
| Flaming drips | Residues reaching the chamber floor must not burn for more than 2 seconds |
| Char length, folded specimen | Not exceeding 1050 mm on any individual specimen |
| Char length, flat specimen | Not exceeding 435 mm on any single specimen |
The retest provision deserves attention. Where an individual specimen’s mass loss deviates from the mean by more than three standard deviations, a retest is triggered, and the same outlier rule then applies to the second set calculated on its own statistics.
That means a single badly behaved specimen does not automatically fail a material, and it also means an inconsistent material can be caught by the spread rather than by the average.
What NFPA 701 Does Not Cover
It is a flame propagation test on hanging textiles, and nothing more.
It says nothing about smoke generation, toxic gas output, or heat release. A fabric can pass comfortably and still produce dense smoke in a real fire.
It is not equivalent to ASTM E84, the Steiner tunnel test, which measures flame spread and smoke development indices on building materials including wall coverings. Codes reference them for different product categories, and passing one does not substitute for the other.
State or local laws may be stricter. California Title 19 has stricter requirements: a maximum char length of six inches and a maximum afterflame length of four seconds. The Canadian CAN/ULC-S109 standard contains features of both standards: the maximum afterflame is two seconds and the maximum char length is 250 mm.
Durability and Retesting
A treated fabric is not permanently treated.
Topically applied flame retardants wash out, dry-clean out, and weather off. Inherently flame-resistant fibers retain performance through cleaning; treated fabrics may not, and the distinction matters enormously for a product that will be laundered.
When the fabric is expected to be cleaned during use, post-cleaning testing will provide a definitive answer. Authorities often require regular retesting of the fabric installation. Some areas have annual renewal periods.
Field match tests carried out by fire officials are another practical consideration. Excessive after-flame of fifteen seconds or more can prompt rejection by an authority performing an informal field check, regardless of what the laboratory report says.
Submission Requirements
Provide enough material to make ten test pieces of 150 mm x 400 mm in the longitudinal direction, plus spares in case retesting is required. Provide an extra length rather than just the minimum.
Areal density in g/m² or oz/yd², since it determines which method applies. If you don’t have the figure, we measure it on receipt. The result determines the route, and it can move a submission from Method 1 to Method 2 before any burning happens.
Construction information like single layer or multiple layers, coating, backing, and any other treatment done is also essential. We need to know if the sample is to be tested as it is or as cleaned to determine which testing procedure to use.
NFPA 701 FAQs
NFPA 701 is equal to ASTM E84?
No. NFPA 701 is used to determine the flame propagation properties of hanging fabrics, whereas ASTM E84 assesses the flame spread and smoke generation from building materials inside a tunnel. They are mentioned in codes for different products and hence cannot be interchangeable.
Does a pass cover smoke and toxicity?
No. NFPA 701 measures flame propagation only; smoke and toxic gas output are separate properties that require separate tests.