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).

6. On-site assembly

6.1. Potential risks during assembly

  • There is a risk of incorrect alignment when modules are being assembled, which could compromise performance of fire barriers and overarching structural integrity of the building.
  • Fire separation and compartmentation must be carefully undertaken to ensure fire performance is maintained at these junctions in line with the approved building warrant.
  • Incorrect assembly sequencing creates a similar risk.
  • The risk of product/component substitution is a risk on site as well as in the factory, which would result in deviation from the original design.
  • Follow on trades could potentially damage placement of fire stopping details. Once modules are connected, it is not possible to undertake an inspection.
  • Once modules are connected it is not possible to inspect correct installation e.g., of fire stopping details. If the verifier decides that a site inspection is necessary, this would need to take place prior to module connections. The verifier may also consider utilising alternative evidence e.g. photography or videography.

6.2. On-site assembly: considerations for verifiers and certifiers

The relevant person is responsible for building in accordance with the approved plans and building regulations by ensuring adequate professional supervision to confirm that the work (onsite and offsite construction) is compliant. This will enable the relevant person or duly authorised agent then to competently certify, sign and submit the completion certificate submission to the verifier. Verifiers make risk based inspections/checks during the construction stage of a building warrant project in line with national Verification during Construction (VDC) Guidance. Checks undertaken by the verifier will be influenced where a Certifier of Construction is being used.


  • What site inspection or other checks are needed in line with Verification during Construction Guidance, and if so, consider carefully the timing of any early or intermediate stage inspection in this context.
  • Is there is evidence that the original specification as designed, is being assembled on site. This may include photographic evidence to confirm the use of the specified materials and components.
  • Is there is photographic evidence (showing the date) available of fire stopping details, wiring, and plumbing once installed, before modules were connected – to provide assurance they were correctly installed.

In the event that damage is detected during an inspection, the relevant person (owner or developer) should confirm the remedial action that will or has been taken to remedy any damage.

  • In the event of any damage or other adaption/variation including component substitution, there is a need to validate that the design remains compliant (by checking with the Certifier of Design (or manufacturer).
  • Any design changes should be validated by submitting an amendment of building warrant application evidencing compliance.



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