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).

2. General points

While this document provides high-level guidance, it should be noted that in the event of further queries relating to the verification of innovative or unusual constructions, opinion can be sought from LABSS.

It should be noted, when assessing applications that propose the use of MMC:

  • Existing quality assurance standards[6], accreditation and relevant legislation are applicable to offsite construction in the same way as onsite construction[7], for example:
    • ISO
    • CE marking (under the Construction Products Regulation[8] or other EU Directives and Regulations)
    • British Standards
    • Codes of Practice
    • European Standards
    • Product certification schemes (certification body accredited by UKAS)
  • Where possible, product standards which specifically assess/test/accredit MMC products or systems should be specified – however it should be taken into account that at the time of writing, there are a limited number of relevant standards.
  • There are a number of accreditation schemes for MMC, however there is no universal certification scheme.
  • There are two accreditations for the use of MMC which are most widely used in industry– Build Offsite Property Assurance Scheme (BOPAS) and NHBC Accepts. Both provide assurance that delivery has been undertaken to a set of defined processes, which have been assessed to meet their standards. In January 2021, the BRE launched its own accreditation scheme for MMCBPS 7014. However, it should be noted that these accreditations have been designed to meet their own, self-set standards and they do not set out to align with the standards set in the Building (Scotland) Regulations 2004. Therefore, these accreditations alone are not sufficient to demonstrate compliance with the Scottish building regulations and standards.
  • There are some processes which have been written specifically for the use of MMC – for example, RIBA/BSRIA Plans of Work and the BSRIA Design Framework for Building Services[9]. While it is not essential that these processes have been used, applicants may wish to include evidence of adherence to these MMC specific processes as additional assurance.

Evidence of BOPAS, NHBC Accepts, or BPS 7014 accreditation should provide assurance that products and processes specific to MMC have been risk-assessed and subject to comprehensive inspection. The verifier will still need to be satisfied that there is sufficient evidence to demonstrate that the applicable building standards have been met in full.

  • The Scottish Type Approval Scheme

The Scottish Type Approval Scheme (STAS) offers national approvals of standard building types, mainly aligning with the volumetric model of MMC where a design and specification will be replicated regardless of geographical location. STAS can also address a national approval of systems including innovative designs or building elements, prepared by designers and developers aligning both with volumetric and panelised MMC.

STAS is applicable for both domestic and non-domestic projects and is used to support building warrant applications in Scotland. STAS produces savings in time in the building warrant approval process, supports national consistency of assessment and may be particularly well suited to less familiar MMC products – allowing the main verification assessment process to take place before any building warrant is submitted.

STAS national approvals can also include conditions and wider information that may support and inform both the verification of design and the approach to reasonable inquiry onsite.

All Scottish Local Authority verifiers accept STAS approvals.

  • Fire Service Consultation

The Scottish Fire and Rescue Service (SFRS) have an interest in certain types of MMC developments involving closed panel or volumetric construction beyond the current building warrant statutory consultations primarily in the interests of fire fighter safety in the event of a Fire (see Section 3.3)



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