Last year, on a project in Chengdu, the client suddenly notified procurement that fire inspection and acceptance required all carpets to provide a B1-grade test report. The supplier replied, ”Some of the test reports are B1 grade, but the current batch hasn’t been sent for testing yet.” The project was delayed by two weeks as a result. Just calculate the comprehensive cost of the hotel’s preparation period per day—at least over a hundred thousand.

I’ve seen this kind of situation more than ten times over the past few years. Honestly, most hotel procurement teams” understanding of flame-retardant standards stops at ”as long as there is such a thing,” and very few people really figure out:How exactly is B1 grade tested? Can different testing standards be mutually recognized? Is everything settled once you get the report?

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I. What exactly is B1-grade flame retardancy testing?

First, let’s clarify one concept. The domestic hotel carpet flame-retardant requirement is based on GB 8624-2012 "Classification for burning behavior of building materials and products"which divides combustion performance into four grades:

Grade	Name	Applicable scope in hotels
Grade A	Non-combustible materials	Evacuation stairwells, front rooms of fire elevators, etc.
B1 grade	Hard-to-burn materials	Guest rooms, corridors, banquet halls, meeting rooms
B2 grade	Combustible materials	Generally not suitable for hotel public areas
B3 grade	Highly flammable materials	Prohibited from use

What most people understand as ”B1 grade” is actually a composite indicator. According to GB 8624, B1 grade must meet the following conditions at the same time:

1️⃣ Critical Heat Flux (CHF) ≥ 4.5 kW/m²—In plain terms, this means the material can self-extinguish after the fire source is removed and does not continue burning

2️⃣ Smoke toxicity rating not lower than t1—The toxicity of smoke generated by carpet combustion must not exceed the limit

3️⃣ Flaming drips must not ignite the filter paper—The molten dripping material must not become a new source of ignition

What is often overlooked here is item 2. Many carpet materials are inherently flame-retardant and have no problem, but after adding flame retardants, the combustion smoke toxicity exceeds the limit and still cannot pass B1. We sent a batch of samples to SGS for testing; the initial flame retardancy all passed, but the smoke toxicity all triggered alarms—the flame retardant itself became the source of the problem.

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II. B1-grade testing hides several ”traps”

Trap 1: The test standard does not match the application scenario

The most common flame-retardant test methods for domestic hotel projects are:

Test standard	Test content	Application scenario	Relationship with B1 grade
GB/T 11785-2005	Radiant heat source method (critical radiant flux)	For flooring materials only	Mandatory test item for B1 grade
GB/T 8626-2007	Ignition and combustion performance (30s/15s)	General building materials	B1-grade auxiliary indicator
GB/T 17658-1999	Carpet combustion performance test	Vertical carpet burning	Additional requirement for some projects
ASTM E648	Critical radiant flux (U.S. standard)	International brand hotels	Method referenced by NFPA 101

The biggest trap I’ve stepped into: Some test reports provided by suppliers are ASTM E648 Class I, which can only be said to comply with the U.S. NFPA 101 standard, and there is no direct correspondence between that and GB 8624 B1 grade. For international brand hotels operating in China, domestic fire acceptance still looks at the national standard report.

Trap 2: The sample submitted for testing and the supplied product are two different things

This may be the most common problem in the industry. When submitting samples for testing, a batch of material used a special flame-retardant formula and process, but during mass production, to cut costs, it was replaced with ordinary yarn or a lower-GSM backing. The test report is real, and the product is real too — but they are not the same thing.

Last year, when supplying a project in East China for an InterContinental hotel, we proactively requested that during shipment,tripartite batch sampling inspectionbe conducted and sent to SGS for retesting. It was not that we did not trust our own process; rather, from yarn entering the factory to finished goods leaving the factory, any fluctuation in any process could affect flame-retardant performance. In the end, the report came back with everything qualified, the customer was reassured, and we felt at ease as well.

💡 Tip: Add one clause to the procurement terms: ”retesting by batch sampling of mass-production goods” — the cost is usually 3,000-5,000 yuan per test, negligible compared with the value of the entire carpet batch, but it can close the 99% risk gap.

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III. Flame-retardant differences among carpets with different processes

Not all carpet flame-retardant solutions are the same. Different materials and processes have completely different underlying logic for flame retardancy:

Nylon 66 carpet (mainly tufted process):

• Nylon itself has an oxygen index (LOI) of 20-22%, making it a combustible material
• Flame retardants must be added; the mainstream solution isphosphorus-based flame retardant + anti-dripping agent
• The flame-retardant treatment cost increases by about 8-15 yuan per square meter
• Note: flame retardants affect color fastness, and the impact is more obvious on darker colors

Wool carpet:

• Wool’s natural oxygen index (LOI) is 25-28%, and its natural flame resistance is better than synthetic fibers
• However, wool produces smoke when burning, so smoke toxicity requires special attention
• Pure wool carpets can mostly reach B1 level in GB 8624 testing, but when pile density is below **1000g/㎡**, auxiliary flame-retardant treatment is required

Hand-tufted carpet:

• The cotton backing is the weak link in flame retardancy
• Our factory’s approach is to useflame-retardant treated cotton backing + flame-retardant latex, providing dual protection
• The hand-tufted carpet supplied in 2023 for a Marriott project in Chongqing, after TÜV testing, had a critical heat flux of6.8 kW/m², far exceeding the B1 threshold

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IV. After getting a B1-level report, what else does procurement need to do?

Step 1: Confirm the product scope covered by the report

The test report will clearly state the product model, batch number, and specification parameters. Check whether they match the SKU you purchased. Some suppliers use one report to cover more than ten models, but in fact only one was tested.

Step 2: Confirm the qualification of the testing institution

Domestic recognized flame retardant testing institutions:

• National Fire Building Materials Quality Supervision and Inspection Center (Dujiangyan, Sichuan)
• National Building Fire Product Safety Quality Supervision and Inspection Center (Beijing)
• Third-party: domestic laboratories of SGS, Intertek, and TÜV
• Inspection reports issued by the above institutions are all recognized for fire acceptance

Step 3: Confirm the validity period of the report

Many purchasers do not know this—testing reports usually do not have a strict validity period, but industry practice recommendswithin 2 yearsreports for the same product can be accepted. If your product process, raw materials, and formula have not changed, you can keep using it. But if there is any change, it must be retested.

Step 4: Prepare an ”emergency plan”

One suggestion we give clients: reserve **3%-5%** of spare blankets for each project, from the same batch and process as the main lot. In case a certain area requires sampling during acceptance, it will not affect the overall schedule.

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5. Flame retardant standard trends for 2026-2027

The release of the “Technical Regulations for Evaluating the Combustion Performance of Building Interior Materials” (draft for comments) by the China Academy of Building Research at the end of 2025 sent a signal:Requirements for smoke toxicity levels are being tightened. The current t1 level is the entry threshold, and the new regulations may require key areas to reach t0 level.

What does this mean? The impact on carpet manufacturers is direct—flame retardant formulations need to be re-optimized. The old approach of simply increasing the amount of flame retardant to meet the standard will not work, because the more flame retardant used, the higher the smoke toxicity may be. The solution is to start from the yarn raw materials side, choosing base fibers with a higher oxygen index and reducing reliance on flame retardants.

Since 2024, the R&D team at Yisen Carpet has been working on this—together with two domestic chemical fiber factories, it developedmodified nylon 66 yarnwith the base oxygen index increased to24%and the amount of flame retardant reduced by about35%while smoke toxicity remains stable at t0 level.

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Back to the acceptance delay case mentioned at the beginning

The essence of the problem is not whether there is a report, but whether the purchaser manages flame retardancy as a ”systematic indicator.” The report is only the result; from raw materials to process to quality control to reinspection, if any link in the chain is disconnected, that piece of paper is just a formality.

If you are preparing a hotel carpet purchase, here are a few suggestions:

• Confirm whether you actually need GB 8624 B1 level or whether the project has other requirements
• After receiving the test report, first check the product batch, testing method, and whether all SKUs are covered
• Include a clause in the procurement contract for random sampling and retesting of bulk goods
• Confirm with the supplier the impact of the flame retardant solution on color fastness and texture

Our team has served more than a hundred hotel projects, and our experience with flame retardancy is: the earlier the standards are communicated, the smoother the later acceptance will be. If you need a specific testing plan or report template reference, you can directly communicate with the technical team at Yisen Carpet—after all, product safety and compliance are the common bottom line for both manufacturers and purchasers.

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[Note]

• Data sources in the text: GB 8624-2012 "Classification for burning behavior of building materials and products", GB/T 11785-2005 "Determination of critical heat flux for floor coverings", China Academy of Building Research "Technical Specification for Evaluation of Burning Performance of Interior Materials for Buildings" (Draft for Comment 2025), and Yisen Carpet Laboratory measured data
• The reference price for testing fees is based on SGS East China Laboratory’s 2025 quotation
• The case data has been anonymized