Modern methods of construction: guidance for building standards verification
Provides guidance to Local Authority verifiers and Certifiers as defined under the Building (Scotland) Act 2003 when assessing building warrant applications and certifying works which use Modern Methods of Construction (MMC).
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3. Building warrant assessment
3.1. Potential risks at the outset
Potential risks relating to the use of MMC to consider upon receipt of the building warrant application are:
Does the proposed MMC product achieve and evidence compliance with all the necessary building regulations and standards.
- MMC projects rely on Design for Manufacture and Assembly (DfMA), and therefore there is a risk that the design will not be fit for purpose if there is not sufficient consideration given to material/product size and weight for transportation prior to assembly. While this is a logistics rather than a regulatory issue, it is flagged here as damage during transportation could mean the design approved in the building warrant is compromised, potentially leading to non-compliance.
- There is a risk that the design will not be built as specified to meet the building warrant approved design if a design freeze is not imposed before manufacture commences in the factory. Such changes may not be readily identified on site particularly in the case of closed panel and volumetric units.
- Expert input may be needed at the design phase in relation to structural fire engineering. The insurance industry, firefighting, and fire safety bodies have flagged concerns about fire risks within MMC. While there is no strong evidence to suggest fires are more likely to occur in an MMC building (compared with a traditionally constructed building), if a fire occurs it could result in more severe consequences in an MMC building because of the typically greater occurrence of voids and cavities through which smoke and fire could travel rapidly if not adequately controlled. These risks should therefore be considered in the design, via detailed specification and testing that clearly demonstrates compliance with the building regulations, and also be considered within the development of the CCNP.
- The product specification and component use is required at building warrant, i.e., how it will be used and installed reflecting geographical location factors. For example, certain products/components require additional treatment if used in a particular region such as coastal or may require a particular type of installation depending on matters such as the building height and exposure.
- For high rise, the more compartments that are stacked on top of each other, the greater the potential risk is for cumulative error if the design and/or subsequent installation is not fit for purpose.
- Individual components and products are subject to testing, but innovative materials may not have been tested comprehensively to consider how a full system or module performs (in the event of fire; structural resilience; energy efficiency etc.). There is no mandatory requirement for performance testing of individual panels or full modules. Standard fire testing and approaches typically assess individual details and do not test connections i.e. how one module is connected to the floor. Volumetric systems are not tested in their entirety in a way that takes the height of the building into account.
3.2. Building warrant assessment: considerations for verifiers
- Is there sufficient and appropriate independent product testing beyond trade literature or manufacturers declarations which demonstrates compliance in accordance with Section 0.8 - Durability, workmanship and fitness of materials (Regulation 8).
- Additional testing of innovative materials and their use in combination may be needed to provide assurance of compliance with building regulations before approval can be considered, particularly in the areas of durability and fire safety.
- Is there evidence of the MMC system/product accreditation e.g., BOPAS, NHBC Accepts, BPS 7014.
- Is there evidence that products/components/systems specified meet the requirements of British or equivalent European standards at the time the application was made?
- Is there evidence of that products or systems are covered by an independent UKAS accredited third-party approval body and there is evidence of the testing body accreditation.
- Are the products/components CE marked as required by the Construction Products Directive until 1st January 2023, or UKCA marked after that date.
- Is there evidence that product testing and certification has taken place in the context of its intended use i.e., tests are suitable for MMC rather than for traditional forms of construction.
- In the absence of appropriate testing, is there evidence of bespoke testing and certification (for example, BBA Certification).
- For timber frame panels, do panel systems have quality assured systems in place which are registered with the STA or BM TRADA?
- For any Section 2 Fire or other 'alternative to guidance' solution, has this been developed by a suitably qualified professional with experience in the use of MMC.
- For innovative systems, whether fire testing has been undertaken against BRE loss prevention standard 1501. This standard is intended to provide a fire test, performance and classification system for innovative building systems used in building construction. Fire test results from LPS 1501 may be used as evidence contributing towards compliance with the mandatory building standards.
3.3 Consultations with the Fire Authority (SFRS)
- In addition to the statutory building warrant consultations with the fire authority required under Section 11 of the Building (Procedure) (Scotland) Regulations 2004, the SFRS may have an interest in certain other MMC building warrant application beyond the types requiring statutory consultation.
- For example for buildings of closed panel, volumetric or innovative MMC construction, the SFRS invites consultation in line with Regulation 10 of the Building (Procedure) (Scotland) Regulations 2004 for MMC as above in the following circumstances and with the verifier stating if the consultation being for comment or being simply notification for awareness:
- Domestic building or residential building with any storey at a height of more than 7.5 metres above the ground
- Educational establishments (schools, colleges and universities), community/sport centres
- Residential care buildings and
- any other MMC buildings the verifier may think appropriate
All SFRS Consultations or Notifications should be via firstname.lastname@example.org
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