Building Safety Act · Mandatory · Construction
Cladding and Facade Specification Record
A record of external wall system specifications including cladding materials, insulation, and fire performance data.
Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. BSA 2022 / Building Regs B remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.
| Legal basis | BSA 2022 / Building Regs Part B |
| Status | Mandatory — golden thread requirement for all HRBs |
| Responsibility | Designer / Contractor (with fire engineer input) |
| Post-Grenfell | Cladding specification was a central finding of the Grenfell Tower Inquiry |
| Material requirement | HRBs over 18m require cladding Class A2-s1,d0 or better (limited combustibility) |
1. Cladding Specification — The Most Safety-Critical Element of an HRB Facade
The external wall system of a high-rise residential building is the most safety-critical element from a fire spread perspective. The Grenfell Tower Inquiry established that ACM cladding with polyethylene core propagated fire around the building at devastating speed. The Building Safety Act 2022 and Building Regulations Part B have introduced strict requirements for external wall fire performance precisely because of this risk. The cladding/facade specification record is the evidence that these requirements have been met.
The specification record must document the actual materials installed — not the materials specified in the design. If substitutions occur during construction (a cladding product becomes unavailable; a contractor proposes a cheaper alternative), these must be change controlled (K5) and the specification record updated to reflect the actual installed system. The fire performance evidence must relate to the system as installed.
Any substitution of external wall materials during construction is almost certainly a Category 3 notifiable change — do not substitute without BSR approval
A change from the specified cladding product to a different product, or from the specified insulation to a cheaper alternative, is a change to the fire strategy and external wall specification that was reviewed by the BSR at Gateway 2. Such changes are almost certainly notifiable changes under the BSA change control regime. A contractor who substitutes an external wall material without BSR approval, without fire engineering assessment, and without updating the golden thread is committing a serious BSA compliance failure.
2. Cladding / Facade Specification Record — Content
The following table sets out the required content of the cladding/facade specification record for an HRB.
| Field | Description |
|---|---|
| Building reference | HRB name, address, building height. |
| Element reference | Facade zone/elevation reference. Drawing reference. |
| External layer (cladding) | Product name and manufacturer. Product reference (as supplied). Fire classification (EN 13501-1 Euroclass). Test evidence reference. Delivery and installation batch records. |
| Insulation | Product name and manufacturer. Type (e.g. mineral wool, PIR, EPS). Fire classification. Test evidence reference. |
| Cavity barriers | Product name and manufacturer. Locations per approved drawing. Fire resistance period. Inspection record confirming installation. |
| Fixing system | Fixing type, manufacturer, structural capacity. Installation inspection reference. |
| Substrate | Substrate type and fire performance. |
| Fire test evidence | BS 8414 test report reference; or BR 135 desktop study reference. Confirming the specified system meets Part B requirements. |
| As-built vs specified | Confirm any variations from the approved specification. Change control references for any substitutions. |
| Installed by | Contractor. Inspection sign-off. Date. |
3. Common Mistakes
Using a BS 8414 test report for a different system than what is installed
BS 8414 test evidence must relate to the system as actually installed. A test report for System A cannot be applied to System B (with a different insulation or a different cladding product) without a desktop study confirming the systems are sufficiently similar. Using inapplicable test evidence is a serious compliance failure.
Not inspecting and recording cavity barrier installation
Cavity barriers are the passive fire protection elements that prevent fire spreading horizontally and vertically within the external wall cavity. They must be installed in the correct locations, with no gaps. A photographic inspection record confirming correct installation before cladding panels are fixed is essential — once cladding is fixed, the cavity is inaccessible.
Not recording product batch/delivery information for cladding materials
Knowing which product was specified is not enough — the golden thread should record which actual product (by batch/delivery reference) was installed. If concerns arise about a product in the future, traceability to delivery records allows the building owner to identify whether their building is affected.
Not updating the specification record for material substitutions
Every material substitution must be recorded and the fire performance evidence updated.
Not engaging a fire engineer to review the external wall specification
The fire engineering assessment of the external wall system — particularly where alternative approaches to Approved Document B are used — requires a qualified fire engineer. A contractor or designer without fire engineering competence selecting external wall materials based on cost or availability alone is not meeting the BSA competence requirements.
4. Frequently Asked Questions
What materials are permitted for cladding on HRBs over 18m?▾
Approved Document B (current version) requires that for new HRBs over 18m: the outer cladding material must be Class A2-s1,d0 or better (limited combustibility); the insulation must also be limited combustibility. This means that most combustible insulation materials (PIR, EPS) are not permissible as the principal insulation layer in new HRBs over 18m. Mineral wool and glass wool insulants are limited combustibility. ACM with polyethylene core is not permitted. Verify the current Approved Document B requirements at gov.uk/building-regulations.
What is an EWS1 form and is it required for new HRBs?▾
The External Wall Survey 1 (EWS1) form was developed post-Grenfell to provide lenders and valuers with an assessment of external wall fire risk in residential buildings. It is completed by a qualified fire engineer. For NEW HRBs with a compliant external wall system and full documentation, an EWS1 should be straightforward — the specification record and test evidence are the basis. For EXISTING HRBs with unknown or suspect cladding, the EWS1 is a key assessment tool (alongside PAS 9980:2022).
What is PAS 9980:2022?▾
PAS 9980:2022 is a publicly available specification published by BSI providing a methodology for fire risk appraisals of external wall construction in existing multi-storey, multi-occupied residential buildings. It replaced the government’s consolidated advice note and provides a more structured and proportionate framework for assessing the fire risk of existing cladding systems. It is used for the EWS1 process for existing buildings and provides guidance on remediation requirements.
What are cavity barriers and why are they critical?▾
Cavity barriers are fire-stopping elements installed within the external wall cavity to prevent fire spreading horizontally and vertically through the air gap behind the cladding. They must be installed at: every floor junction; around every opening (windows, doors); at verges and sills; and at specified intervals. If cavity barriers are not installed correctly — if there are gaps, if they are compressed out of position, or if they are omitted — the cavity creates an unobstructed path for fire to travel up the building. Grenfell demonstrated the consequences. Cavity barrier installation inspection is one of the most critical construction phase hold points for HRBs.
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