EN 13773 Class 1: The Highest European Standard for Curtain Flame Retardancy

In the European Contract Textiles market, EN 13773 Class 1 represents the highest safety standard for curtains and suspended fabrics. For suppliers participating in public building tenders across EU countries (such as France, Germany, Spain, and the Netherlands), providing fabrics with certified EN 13773 Class 1 compliance is a core requirement for meeting fire safety regulations.

What is the EN 13773 Class 1 Standard?

EN 13773 Class 1 is a unified European classification standard designed specifically for the burning behaviour of curtains and drapes.

The standard aims to coordinate the differing fire safety codes across EU member states through a common technical language. EN 13773 is not a single test method but a comprehensive classification scheme. It categorizes fabric flame retardancy from Class 1 (highest) to Class 5 (lowest) based on the combined results of two specific laboratory tests: EN 1101 (Ignitability) and EN 13772 (Flame Spread). Class 1 represents the highest safety level within this system, requiring that the fabric resists ignition and exhibits minimal flame spread even under radiant heat conditions.

Scope of Application for EN 13773

The EN 13773 standard explicitly applies to vertically suspended interior textiles, primarily covering curtains, drapes, and fabric blinds.

This standard applies to all forms of vertically hanging fabrics, regardless of fibre composition or weave structure. It is important to note that EN 13773 does not apply to upholstery fabrics (which typically fall under EN 1021) or flooring materials (which fall under EN 13501-1 Flooring). Clarifying the scope of the standard helps procurement officers avoid the misapplication of testing standards across different textile categories.

The EN 13773 Classification System (Class 1 – Class 5)

EN 13773 divides the flame retardant performance of curtain fabrics into five classes, with Class 1 being the highest level and Class 5 being the lowest. This classification is based on the fabric’s resistance to ignition and the speed of flame propagation across its surface.

Understanding this hierarchy is critical for material selection, as different building risk levels mandate different Class requirements:

Classification	Technical Performance Description	Recommended Application Scenarios
Class 1 (Highest Level)	Non-ignition and negligible flame spread. Under simulated radiant heat, flames do not reach the first marker thread, with no flaming debris and no flashover.	High-Risk Public Areas: Theatre stages, large hotel lobbies, hospital wards, schools, emergency evacuation routes.
Class 2	Non-ignition and limited flame spread. Flame spread speed is controlled, satisfying general public safety requirements.	Medium-Risk Public Areas: Offices, standard commercial retail spaces, meeting rooms.
Class 3	Non-ignition but evident flame spread. Fire spreads after the ignition source is removed, though the fabric itself resists ignition from small sources.	Low-risk semi-public spaces or specific residential facilities.
Class 4 / 5	Ignitable. The fabric ignites upon contact with a flame source and offers no effective fire protection.	Domestic Use Only. Strictly prohibited for use in any public contract projects.

Test Methods and Pass Criteria for EN 13773

To obtain EN 13773 Class 1 certification, a fabric must sequentially pass the EN 1101 Ignitability Test and the EN 13772 Flame Spread Test, meeting both “Non-ignition” and “No Flame Spread” criteria.

The rating process follows a strict logical sequence; failure at any stage results in a downgraded classification:

Step 1: Ignitability Test (According to EN 1101)

• Test Description: The fabric is suspended vertically, and a standard small flame is applied to both the surface and the bottom edge.
• Pass Criteria: The fabric must demonstrate “Non-ignition.” This means the fabric itself must not ignite upon contact with the flame source. If combustion occurs at this stage, the fabric is immediately categorized as Class 4 or Class 5 and is ineligible for further testing.

Step 2: Flame Spread Test (According to EN 13772)

Test Description: This is an advanced test for Class 1 and Class 2 candidates. While the bottom of the fabric is subjected to ignition, the surface is simultaneously exposed to a radiant heat flux from a large radiator, simulating the intense heat of a real fire.

Class 1 Pass Criteria:

• Flame Control: The flame must not spread to the first marker thread.
• No Debris: No flaming debris or molten droplets shall detach from the specimen.
• No Flashover: No flashover (rapid ignition of the entire surface) shall occur.

Comparison: EN 13773 vs. Common European Standards (M1, B1)

While EN 13773 Class 1, French M1, and German B1 all represent “Flame Retardant” safety levels physically, acceptance varies by country due to local regulations.

Although the EU introduced EN 13773 to unify standards, national standards still hold legal or customary authority in practical engineering procurement:

Standard System	Primary Country	Relation to EN 13773 Class 1	Procurement Advice
EN 13773 Class 1	EU General	The Standard Itself	Universally applicable in Poland, the Netherlands, Scandinavia, and countries accepting EU norms. A passport for cross-border projects.
NF P 92-503 (M1)	France	Technically Similar	M1 certificates are mandatory for French projects. Although Class 1 performance is physically close to M1, French fire officers typically demand the M1 label. Dual certification is recommended for high-end fabrics.
DIN 4102 (B1)	Germany	Safety Level Equivalent	B1 certificates are mandatory for German projects. B1 uses a different test method (Brandschacht), but falls into the same “Flame Retardant” safety tier.
BS 5867 Type C	United Kingdom	Different Logic	UK standards prioritize durability after 50 wash cycles. EN 13773 certificates are generally not accepted in the UK; BS 5867 testing is required separately.

Fabric Durability and Washing Requirements

The EN 13773 standard enforces mandatory verification of “Wash Durability.” If a fabric label indicates it is washable or dry-cleanable, the burning test must be repeated after the prescribed cleaning cycles to determine the final classification.

This regulation ensures safety throughout the fabric’s usage lifecycle, preventing the risk of “temporary flame retardancy”:

• Pre-treatment Procedure: Typically involves 12 or 50 standard wash cycles (according to ISO 10528 or ISO 6330) before testing.
• Advantage of IFR (Inherently Flame Retardant) Fabrics: Since the flame retardant properties of IFR fabrics (e.g., modified polyester) are intrinsic to the molecular structure of the fibre, performance does not degrade with physical washing, ensuring stable Class 1 compliance.
• Risk of FR Treated Fabrics: Fabrics relying on chemical coatings may lose flame retardant agents after multiple washes, potentially leading to test failure or a downgrade from Class 1 to Class 3.

Common Misconceptions and Precautions

• Misconception 1: “Class 1 is the lowest level.”
  Correction: In the EN 13773 system, Class 1 is the highest and safest level. This is contrary to some other standards (where higher numbers imply better performance), so procurement officers must be vigilant.
• Misconception 2: “Class 1 is equivalent to Non-Combustible (A1).”
  Correction: EN 13773 Class 1 remains a textile product. It will char under extreme heat but is difficult to ignite. It is not equivalent to A1 materials like stone, glass, or metal which do not burn at all.
• Misconception 3: “Holding a Class 1 certificate allows export to the USA.”
  Correction: No. The US NFPA 701 standard uses completely different testing methods and ignition mechanisms. Exporting to the USA requires separate NFPA 701 testing.

Frequently Asked Questions (FAQ) about EN 13773