Fibre Reinforced Facade Encyclopedia: Testing and standards
BS 8414 is the British Standard test method for the fire performance of external cladding systems. A complete wall system is built full scale on a rig standing at least 8 metres above a combustion chamber, a timber crib is burned in the chamber for 30 minutes, and thermocouples and observers record how fire moves up the face of the wall and inside its cavity. BS 8414 is a method only. It produces measurements, not a verdict; the pass criteria come from the BRE classification document BR 135.
BS 8414 tests a system, not a product. The cladding, the cavity, the insulation, the membrane, the brackets, the cavity barriers and the substrate are all built as they would be on the building. A single change to any of them puts the result outside the scope of the test unless an extended application assessment covers it.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Standard | BS 8414-1 and BS 8414-2 Fire performance of external cladding systems | Test methods, first published 2002 |
| Part 1 | System applied to a masonry substrate | Rendered and insulated masonry, rainscreens on blockwork |
| Part 2 | System applied to a structural steel frame | Framed and infill wall construction |
| Rig | Main face at least 8 m above the chamber opening, plus a return wing at least 1.5 m wide | Total rig height about 9 m |
| Fire source | Timber crib of about 400 kg in a chamber 2 m wide, 2 m high and 1 m deep | About 4,500 MJ over 30 minutes, peaking near 3 MW |
| Measurement levels | Level 1 at 2.5 m and Level 2 at 5 m above the chamber opening | External face and cavity thermocouples at each level |
| Classification document | BR 135 Annex A criteria | External and internal fire spread |
| Extended application | BS 9414 assessment of variations to a tested system | Replaces informal desktop studies |
| UK regulatory role | Alternative route in Approved Document B where the combustible materials ban does not apply | Thresholds vary by building use and height |
| Related tests | AS 5113 (Australia), NFPA 285 (United States), CAN/ULC S134 (Canada) | Not interchangeable |
Part 1 and Part 2, and why the substrate matters
The two parts of BS 8414 differ in what the system is fixed to. Part 1 uses a masonry substrate, which represents an insulated render system or a rainscreen on a solid blockwork or concrete wall. Part 2 uses a structural steel frame, which represents framed construction with an infill wall behind the cladding. The difference is not academic: a framed wall gives fire a different path into and through the build-up, and a result obtained on one substrate does not automatically cover the other.
This is the same principle that runs through every full-scale facade test. The subject of the test is the assembly, and the report defines the assembly it covers, including the insulation type and thickness, the cavity depth, the cavity barrier specification, the fixing arrangement and the panel thickness.
What the instruments record and how BR 135 reads them
Thermocouples sit on the external face and inside the cavity at two levels: Level 1, 2.5 metres above the top of the combustion chamber opening, and Level 2, five metres above it. The clock that matters is not the moment of ignition but the start time, defined as the moment the external Level 1 thermocouples exceed 200 degrees Celsius above their starting temperature. BR 135 then judges fire spread against that start time.
External fire spread has failed if any external thermocouple at Level 2 exceeds 600 degrees Celsius above ambient for a continuous period of 30 seconds within 15 minutes of the start time. Internal fire spread is judged the same way on the cavity thermocouples. The crib burns for 30 minutes and observation continues afterwards, with mechanical failure, pool fires, burning debris and collapse all recorded. The BR 135 criteria themselves are set out on the BR 135 page.
Where the UK regulations allow it
Regulation 7(2) of the Building Regulations in England prohibits combustible materials in the external walls of relevant buildings above a stated height, with a defined list of exempt components, and for buildings caught by that prohibition a BS 8414 test is not an alternative route. Below the threshold, and for buildings outside the categories covered, Approved Document B offers BS 8414 with BR 135 as one of the ways of showing that external fire spread is adequately resisted, alongside the material class route based on EN 13501-1.
The height thresholds and the categories of building covered have changed more than once since 2018, and the devolved administrations of Scotland, Wales and Northern Ireland set their own.
Extended application instead of desktop studies
Because no supplier can test every build-up an architect will draw, the industry long relied on written assessments extending a tested result to untested variations. The practice attracted sustained criticism for inconsistency, and BS 9414 was published to put it on a defined basis. It sets out which variations may be assessed, the direction each must take to be considered no worse than the tested system, and the competence and reporting requirements for the assessor.
For a specifier the practical question is simple. If the wall as designed is not the wall as tested, ask which document covers the difference: a second test, or a BS 9414 assessment naming the reference test and the specific variations.
BS 8414 alongside AS 5113 and NFPA 285
AS 5113 adopts the BS 8414 rig and fire source and the BR 135 criteria, then adds Australian criteria on burning debris and on the condition of the system after the test. A system tested for an AS 5113 classification has therefore been tested to BS 8414, while a BS 8414 test alone does not produce an AS 5113 classification. NFPA 285 is a different test entirely, with a two-storey rig, a room burner and a window burner, and flame height rather than thermocouple temperature as its principal criterion.
ShapeShell-RT was tested to BS 8414 and AS 5113 at BRE Global and met all AS 5113 criteria, with no flame spread, no flaming debris and no breach of panel integrity recorded. ShapeShell-RT is an FRP system and is not non-combustible, so for a United Kingdom project the full-scale route is the relevant one wherever the combustible materials prohibition does not apply.
Standards and references
- BS 8414-1 Fire performance of external cladding systems: test method for non-loadbearing external cladding systems applied to the masonry face of a building
- BS 8414-2 Fire performance of external cladding systems: test method for non-loadbearing external cladding systems fixed to and supported by a structural steel frame
- BR 135 Fire performance of external thermal insulation for walls of multistorey buildings (BRE), Annex A classification criteria
- BS 9414 Fire performance of external cladding systems: extended application of results from BS 8414-1 and BS 8414-2
- Approved Document B and Regulation 7(2) of the Building Regulations 2010 (England)
- AS 5113:2016 (Australia), NFPA 285 (United States), CAN/ULC S134 (Canada)
Related terms
Questions specifiers ask
Does a system pass or fail BS 8414?
Not in the standard itself. BS 8414 is a test method that produces temperature and observation data. The criteria that decide the outcome are in BR 135, so the meaningful statement is that a system met the BR 135 criteria when tested to BS 8414.
What is the difference between BS 8414-1 and BS 8414-2?
The substrate. Part 1 tests the system on a masonry face and Part 2 tests it fixed to a structural steel frame. A result on one substrate does not automatically cover the other.
Is BS 8414 the same as AS 5113?
No, although they share the rig and the fire source. AS 5113 adopts the BS 8414 test and the BR 135 criteria and adds Australian criteria on burning debris and post-test damage, so an AS 5113 classification is the stricter of the two.
Can a BS 8414 result be used for NCC compliance in Australia?
Not on its own. The NCC references AS 5113 through Verification Method C1V3. A BS 8414 test is the underlying test, but the Australian classification and its additional criteria are what a certifier asks for.
What is a desktop study?
An assessment extending a tested system’s result to an untested variation. In the United Kingdom this is now governed by BS 9414, which defines which variations may be assessed and how the assessment must be reported.
Working on a facade that needs full-scale test evidence? ShapeShell-RT was tested to BS 8414 and AS 5113 at BRE Global and met all AS 5113 criteria. See ShapeShell fire test data
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.