Reaction to fire
Why your SBI result moved when the fixings changed
The mounting and fixing arrangement is part of the tested product. Change the substrate or the screw spacing and you have a different specimen.
4 June 2026Fire performance measured, not asserted
CINDERHOLT tests construction products to their reaction-to-fire and fire resistance performance, and writes the classification report that goes with the result. We have run the furnaces at Templeborough since 1998.
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CINDERHOLT tests to
British, European and ISO fire test standards
- BS EN 13501-1
- BS EN ISO 1182
- BS EN 13823
- ISO 5660-1
- BS EN 1364
- BS 8414
BS EN ISO 1182
Non-combustibility
A 20 mm specimen is held in a furnace at 750 °C for 30 minutes while temperature rise, mass loss and sustained flaming are recorded. It is the gateway test for an A1 or A2 classification, and it is unforgiving — a product either survives it or it does not.
- Furnace stabilised at 750 °C ± 5 °C
- Five specimens per product as standard
- Temperature rise, mass loss and flaming duration reported separately
- Result feeds directly into BS EN 13501-1
BS EN 13823
Single burning item (SBI)
The corner test. Two wings of the product are mounted in an L-shape and exposed to a 30 kW sand-bed burner for 20 minutes while heat and smoke release are measured continuously. Most B, C and D classifications are decided here.
- 30 kW propane burner in a corner configuration
- FIGRA, THR600s, SMOGRA and TSP600s all reported
- Lateral flame spread and flaming droplets observed
- Mounting and fixing recorded in full — it changes the result
BS EN ISO 11925-2
Single flame source
A small 20 mm flame applied to the edge or surface of a specimen for 15 or 30 seconds. Cheap, fast, and the test that most often catches a product before it reaches the expensive ones.
- Surface and edge exposure
- 15 s and 30 s exposure options
- Flame spread to 150 mm measured
- Filter paper used to detect flaming droplets
ISO 5660-1
Cone calorimeter
Oxygen consumption calorimetry at a set irradiance, usually 35 or 50 kW/m². It does not produce a European classification on its own, but it is the most useful development tool we run.
- Irradiance from 10 to 75 kW/m²
- Peak and average heat release rate
- Time to ignition and total heat released
- Smoke production measured in the same run
BS EN ISO 1716
Gross heat of combustion
Bomb calorimetry to establish the potential heat content of a product. Paired with non-combustibility for A1 and A2 classifications, and run on each component of a composite separately.
- Bomb calorimeter, three determinations per component
- PCS reported in MJ/kg
- Composite products broken down by layer
- Homogeneity assessed before testing
BS EN ISO 5659-2
Smoke density and toxicity
Smoke accumulation in a closed chamber under radiant heat, with optional FTIR analysis of the gases produced. Required for rail and marine work far more often than for construction.
- 25 and 50 kW/m² irradiance, with or without pilot flame
- Specific optical density Ds at 4 and 10 minutes
- FTIR gas analysis available
- Rail (EN 45545) and marine (FTP Code) parameter sets
BS EN 1364 / BS EN 1365
Fire resistance — walls and floors
Loadbearing and non-loadbearing elements taken to the standard time-temperature curve in the large furnace. Integrity, insulation and, where relevant, loadbearing capacity are recorded to failure.
- 3 m × 3 m vertical furnace, 4 m × 3 m horizontal
- Standard, hydrocarbon and slow-heating curves
- Integrity (E), insulation (I) and loadbearing capacity (R)
- Deflection and cotton pad results in the report
BS 8414-1 / -2
External wall systems
Full-scale cladding rig with a 3 MW timber crib in the combustion chamber. Nine metres of wall, instrumented, burned once. Nobody runs this test speculatively.
- Freestanding (8414-1) and returned-face (8414-2) rigs
- External and internal thermocouple levels
- Assessed against BR 135 performance criteria
- Full photographic and video record supplied
BS EN 13501-1
Classification reports
The document a specifier actually reads. We prepare classification reports from our own test data and, where the evidence supports it, extended application (EXAP) assessments.
- Classification from A1 to F, with s and d sub-classes
- Direct and extended field of application stated separately
- Field of application limits written in plain terms
- Reissued free of charge if a typographical error is ours
Who sends us work
Tested for
- Insulation manufacturers
- Facade and cladding system houses
- Panel and board producers
- Rail and marine interior fitters
- Architects and fire engineers
- Certification bodies, as evidence
Test, classify, explain
Test
Nine methods on our own schedule, run in our own halls. Nothing on this site is subcontracted without your written agreement.
Classify
Classification reports to BS EN 13501-1 prepared from our own data, with the field of application written in terms a specifier can apply.
Explain
A test engineer walks you through the result, including the parts that did not go your way. Development work goes better when the failure is understood.
From the test halls
Four notes on where fire test programmes go wrong, written for product developers rather than for other laboratories.
Reaction to fire
Classification
A1 and A2 are not two grades of the same thing
One is a pair of tests with no organic content to speak of. The other allows a defined heat contribution and adds the SBI.
19 April 2026
Reporting
What a field of application actually permits
The most common misuse of our reports is applying a result to a thickness, density or substrate that was never tested.
2 February 2026
Fire resistance
Before you book BS 8414
The full-scale rig costs more than every other test on our schedule combined. Six things to settle first.
11 November 2025Get in touch
Tell us the product and the classification you need to reach. If the route you have in mind will not get you there, we would rather say so before you pay for the test.
Submit an enquiryBefore the first test
How much material do you need?
For SBI, two wings measuring 1.5 m × 1.0 m and 1.5 m × 0.5 m, plus spares — in practice about 8 m². For non-combustibility and bomb calorimetry a few hundred grams is enough. We send a written specimen schedule with every quotation so nobody guesses.
Can you tell us the result before the report?
We release the raw data as soon as the test is complete, usually the same day. The classification report follows within ten working days. What we will not do is give an informal opinion on a borderline result and then write something different in the report.
Our product failed. What now?
You get the data, the observations and the video. Most reformulation work then goes through the cone calorimeter, because it is a tenth of the cost of an SBI and tells you whether you have moved the needle before you commit to another full test.
Do you certify products?
No. We test and we classify. Certification is a separate activity carried out by a certification body, and a laboratory that does both has a conflict it cannot manage. Our classification reports are accepted by certification bodies as evidence, which is the correct relationship.