What permittable changes can I make to a fire resistant partition under EXAP?
Guidance on permitted changes under fire test and extended application rules
Fire resistance performance applies only to the specific partition configuration that has been tested. Changes to the construction can invalidate the performance unless those changes are clearly permitted by the extended field of application rules.
This guidance is based on BS EN 15254‑3: ‘Extended application of results from fire resistance tests for non‑loadbearing lightweight partitions’. It explains which changes may be acceptable and which are not, provided all other aspects of the tested system remain unchanged.
This information is generic guidance only. Project‑specific approval must be confirmed through a validated test report, extended application report (EXAP), or formal fire engineering judgement where applicable.
Framing
Permitted |
Not Permitted |
| Increase stud gauge | Decrease stud gauge |
| Decrease stud spacing | Increase stud spacing |
| Increase stud depth | Decrease stud depth |
| Increase stud width | Decrease stud width |
Change the shape or profile of the stud |
Not permitted: Changes that reduce structural capacity or materially alter the stud geometry fall outside the scope of permitted application.
Boarding
Permitted |
Not Permitted |
| Increase thickness of tested board | Substitute tested board type for another, for example “Siniat Fire MR Board” from the tested “Siniat Fire Board” |
| Increase the number of tested board layers | Reduce the number of board layers |
Increase the number of tested board layers while reducing individual board thickness, provided the total lining thickness is not less than that tested |
Change board orientation |
Insulation
Permitted |
Not Permitted |
| Increase Insulation thickness | Add insulation to a system tested without insulation |
Substitute glass mineral wool for stone wool insulation of the same thickness |
Remove insulation from a system tested with insulation |
| Increase insulation density |
Substitute stone mineral wool for glass wool insulation
|
What is not covered by this guidance
The following items are outside the scope of EN 15254‑3 extended application and require separate fire test evidence, an EXAP report, or formal fire engineering justification:
- Changes to partition height beyond tested and assessed limits
- Introduction or modification of service penetrations
- Changes to deflection head details
- Changes to fixing types or fixing centres
- Junction details with floors, ceilings, or adjacent walls
Verification and compliance
Before specifying or installing an extended configuration, confirm that:
- The proposed change is explicitly permitted by EN 15254‑3
- The system remains within the limits of the relevant fire test or EXAP report
- Supporting evidence is current, traceable, and applicable to the exact configuration proposed
If there is any uncertainty, confirmation should be obtained from the system manufacturer or a suitably qualified fire specialist.
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