11.1.9 Installation
MMC systems shall be installed in accordance with the manufacturer’s recommendations and provide satisfactory performance. Installation instructions, in the form of an Installation Manual, shall be produced in a clear and understandable format, include all relevant information, and be distributed to all appropriate personnel. Issues to be taken into account include:
- competence of installers
- preparation
- design, manufacture and erection tolerances
- structural connections
- sealing of joints and temporary openings.
A set of clear installation instructions should be submitted to NHBC, distributed to appropriate personnel, and made available on site in the form of a system Installation Manual and relevant accompanying drawings, detailing the assembly and installation of the system as appropriate. These instructions should cover factory and site assembly as required.
The system Installation Manual should:
- be supported with site-specific information, including drawings, or detailed fixing specifications
- be used as a reference to ensure compliance
- be current and specific to the system variant/type.
The system Installation Manual should contain the information described in Table 2 as relevant for the system.
Table 2: Items included in the Installation Manual
| Topic | Descriptions |
|---|---|
| Roles and responsibilities | • site process and responsibilities of key personnel • competence requirements for installers • duty holders for verification in accordance with the verification plan • key inspection stages and hold points in accordance with the verification plan – ie, hold points, checklists, provision and/or taking of photographic records |
| Scope and limits of application | • overview of the system including a description of key components and/or assemblies • confirmation of limits of application |
| Storage | • process for site storage and correct maintenance and removal of any temporary protection • method of providing adequate ventilation • requirement for periodic condition surveys |
| Tolerances | • clear description of tolerances for substructure (including square/dimensional/straightness and level) • clear description of dimensional tolerances for units and erection • clear description of tolerances for unit junctions and interfaces including cladding finishes |
| Pre-installation checks | • inspection and verification procedure for condition of units prior to and following delivery to site • tolerance survey of the substructure • dimensional survey of units pre-installation |
| Installation procedure | • sequence of erection • method of connecting to foundations • process and detail of structural connections — with a reference to either type, size, centres, quantity, specification of fixings and reference to bolts requiring specific torques (if standard) or reference to drawings for all module connections, panel joints, etc or where this information can be found on site • temporary bracing requirements (if applicable) • checks and verification procedures associated with cavity barriers and fire-stopping • method and verification for the sealing and completion of junctions between units • method and verification procedure for sealing of temporary roofing membranes including temporary openings and lifting points and adequate drainage provision • detail about removal of temporary protection (unless included in the design as part of the system) • tolerance survey of installed units (level/plumb/deviation) |
| Services | • method for connection of building services such that fire protection and damp proofing are not compromised • method for making good of service connection access points in the structure • method for commissioning of services |
| Non-conformities | • remedial action procedure for damaged or non-conforming units |
11.1.9.1 Competence of installers
Installation of MMC systems should be carried out by trained and competent installers. Specialist installers should understand storage and handling procedures, tolerances, and installation methods relevant to the system type, and have been provided with all product technical data sheets and installation guidance documentation.
Systems should be installed by operatives who:
- are competent
- are familiar with the system being installed
- are registered or hold a current and valid certificate confirming that they have been trained by the system manufacturer, supplier, or installer.
11.1.9.2 Preparation
A pre-installation survey of both the foundations and surrounding construction should be undertaken to ensure compliance with the product specification requirements prior to installation of units.
Volumetric systems
A pre-installation survey of service entry points and pop-ups (eg below ground drainage) should be undertaken prior to installation of units to ensure they align.
11.1.9.3 Design, manufacture and erection tolerances
MMC systems should be installed, within reasonable tolerances, in accordance with the design and as defined in the system Installation Manual.
Units should be checked to ensure that they are dimensionally accurate and not deformed in shape before erection commences.
Closed panel systems
Timber frame walls should be installed in accordance with the relevant tolerances in Clause 6.2.4.
Light steel frame walls should be installed in accordance with the relevant tolerances in Clause 6.10.10.
SIPs should be installed in accordance with the System Manual and certification requirements.
11.1.9.4 Structural connections
MMC unit connections should be installed in accordance with the design.
The supporting structure may have local deviations in level along its length or at individual base plate locations, and packing will be required to achieve the required tolerances and to provide for effective load transfer. The type and extent of packing should be in accordance with the System Manual.
Volumetric systems
Connection plates and brackets should not be drilled, cut, or welded unless required by the design.
11.1.9.5 Sealing of joints
Only the materials and method specified in the design should be used for sealing of joints between units and temporary openings. Tapes, sealants, and membranes should be installed in accordance with manufacturer’s instructions.
Before joints between units or temporary openings are sealed, installers should ensure:
- all cavities are dry
- insulation is complete
- all surfaces are clean and dry
- cavity barriers and fire-stops have been installed.
Last updated: 2nd January 2025