• Outputs

    Outputs

DFMA Guide to Timber Panelised MMC

DFMA (Design for Manufacture and Assembly) is an important consideration to optimise and maximise the use of panelised MMC systems. DFMA is an industrialised approach common in many manufacturing environments

Early in the design life cycle, housing designs can be optimised to make best use of panelised MMC, leading to lower costs and improved quality, whilst increasing surety of construction execution.

This guide provides information and knowledge on critical areas of design, such that manufacturing and construction of timber panelised MMC systems, can be maximised and complexities removed.

This work package was delivered by the AIMCH MMC manufacturing partner Stewart Milne Timber Systems. The DFMA guide is targeted at designers and specifiers of homes.

The guide covers 6 core areas of design consideration, providing guidance on the most cost effective way to design homes.

  1. Design Sequence - Key Decisions
  2. Design Constraints – Limiting factors
  3. Structural Principles – Walls, Floors and Roofs
  4. Differential Movement – Cladding interfaces
  5. Building Services – Plumbing and electrical Interfaces
  6. Windows & Doors – openings and setting out

The DFMA Guide acts as a useful prompt to design out or recognise where design decisions will impact construction.

The DFMA Guide, thought to be one of the first its kind, will be used in the development of AIMCH Industrialised Affordable Housing Designs, using panelised timber Offsite MMC technologies.

DFMA in conjunction with Design standardisation and 3D BIM modelling (Building Information Modelling) can be very powerful tools, that can transform housing design and delivery, fuelling more homes, at lower cost. 

 

Timber Panels Installation
L&Q Timber Roof Truss
AIMCH meeting

summary

The AIMCH DFMA Guide to Offsite Timber Panelised MMC, was developed by the AIMCH MMC partner, Stewart Milne Timber Systems. The key objectives were:

To provide information that helps house designers consider MMC. 

To provide detailed guidance on how best to optimise timber panelised MMC systems

To highlight key design decision points critical to the optimisation of MMC

To flag design constraints that must be considered early

To act as a starting point and reference document for designers, new to offsite timber MMC systems

To be user friendly, designed for used by people with a basic understanding of housing design and construction

 

Worker, Stewart Milne Group
L&Q Timber Roof Truss
Timber Panel

 

Journey

A phased development approach was used to create flexible modelling tools for use in construction related manufacturing. Outputs could be used for small basic panelised OSM building systems, as well as large complex systems. The phased approach enabled different tools to be explored and developed.

  • Design Sequence

    Relating to purpose, value of early engagement and the flow of information.

    This section of the AIMCH DFMA Guide focuses on the sequencing, flow and early engagement within the design process. This is critical to drive best value from the DFMA guide.

    AIMCH recognises a key success ingredient is the early engagement with panelised MMC suppliers. This is fundamental to an Industrialised Housing design approach to maximise panelised MMC value.

    This helped to:
    1. Highlight purpose of early engagement with your panelised MMC supplier
    2. Define areas of early opportunity and discussion to drive MMC value
    3. Provide a flow chart showing key decision points and responsibilities within the design team

    This led to guidance on the type of technical requirements housebuilders or developers need to consider when transitioning from conventional methods to panelised MMC systems.

    It also sets guidance on lead in requirements and design decision points, from concept design and planning approval, into detailed production design, across the various design team members – architect, engineer, services providers and MMC supplier.

  • Design Constraints

    Exploring key design considerations such as building height, relationship to ground levels and interaction with facades.

    This section of the AIMCH DFMA Guide focuses on design constraints and key considerations. Timber Offsite Panelised MMC Systems are generally manufactured to order and can be configured to suit any building design. Being flat pack in nature, transportation is less limiting than other MMC systems. This section focused on the building design constraints and not the limitations of the panelised MMC system. It covers key technical and design consideration around regulatory compliance with building heights and fire standards, ground levels and water proofing and support/detailing for masonry and non-masonry facades.

    This helped to:
    1. Develop guidance using proven/reliable solutions, to overcome design issues
    2. Highlight areas to avoid and design out of housing designs
    3. Explain requirements for regulatory compliance with fire safety standards
    4. Offer solutions to design features such as balconies, parapets and cantilevers

    This led to guidance and examples of the types of things housebuilders must investigate and design in/out when developing there housing typologies and detailed production information. A critical consideration is the compliance with differing fire standards relating to building height and complexity, as well as designing in simplicity, for the support of masonry facades

  • Structural Principles

    Relating to structural design/stability, storey rod heights, openings and stairwells

    This section of the AIMCH DFMA Guide is the largest and most important. This area focuses on structural layout, coordination and stability of the housing typology. Getting this right is the most important aspect. This will lead to simplicity and cost effectiveness, improving construction confidence and avoiding commercial surprises.

    It provides an overview of offsite timber panelised MMC systems, advising on structural layout and dimensional setting out. It also investigates possible structural clashes and how to avoid them, as well as providing guidance on floor joist design, holing and notching parameters and optimisation of joist directions/lintel setting out above openings, to avoid complex floor beams.

    This helped to:
    1. Develop guidance using proven/reliable solutions, to overcome design issues
    2. Highlight areas to avoid and design out of housing designs
    3. Explain structural coordination, that must be correct, before determining floor plate layouts and opening configurations
    4. Offer solutions to potential design clashes such as openings, services, lintels and load paths

    This is an important area, simplifying the structural layout, ensuring things line up, providing enough depth for lintels and utilising down stand beams will drive MMC value, leading to lowest cost solutions, simple and effective to build

  • Differential Movement

    Relating to settlement design and detailing, with masonry cladding

    This section of the AIMCH DFMA Guide focuses on the interface between the timber panelised MMC system and the masonry façade. Timber is one of the most sustainable, renewable and natural building materials used today. Due to these natural properties, designers must ensure the detailing interfaces with masonry outer leave, allows for natural settlement as the building dries out.

    In this section the DFMA guide provides information and good practise guidance, on the allowances required and the construction details to be adopted at known settlement locations.

    This helped to:
    1. Develop guidance using proven/reliable solutions, to overcome settlement requirements
    2. Highlight areas to avoid and design out of housing designs
    3. Explains how settlement occurs, what tolerances are needed and where these should be designed into house designs
    4. Offer solutions at key construction interfaces around openings, service penetrations, stairwells and eaves/verge roof lines

    This is an important design consideration, ensuring suitable settlement allowances and detailing is designed into homes, will ensure they perform as expected, over the lifetime of the building.

  • Building Services

    Highlighting design considerations with plumbing, electrical and ventilation services within apartments and housing

    This section of the AIMCH DFMA Guide focuses on the interface between the timber panelised MMC system and building services such as plumbing, ventilation and electrical works. AIMCH partners seeks to build a weather tight, secure and insulated timber panelised MMC system in one day, ideally without scaffolding. This means the external masonry and internal fit out can commence in parallel, reducing build time and improving surety of completion.

    As with any building system, the introduction of 1st fix services after the structural envelope is completed, needs to be managed and services designed to avoid principle clashes with the superstructure. It is important that designers consider, and design integrated services runs, to minimise disruption.

    The DFMA guide provides guidance to help designers through the complex world of services installation within housing.

    This helped to:
    1. Develop guidance using proven/reliable solutions, to easily integrate services
    2. Highlight areas to avoid and design out of housing designs, preventing clashes
    3. Explains how settlement can impact on service risers and penetrations
    4. Offer solutions at key construction interfaces within floor zones, around stairwells, compartment and external walls

    Building services are often overlooked, the AIMCH DFMA Guide provides solutions to commonly occurring services points such as SVP’s, drainage runs, boiler flues, ventilation ducts and below stair electrical installations

  • Windows & Doors

    Highlighting design considerations around construction detailing, sizes and optimisation and features such as bay/corner windows

    This section of the AIMCH DFMA Guide focuses on the setting out, dimensional coordination and detailing around openings. Design standardisation and brickwork setting out, are important design considerations, to reduce cost and maximise brickwork trades.

    In this section the DFMA guide provides information and good practise guidance, on the allowances required and the construction details to be adopted around openings.

    This helped to:
    1. Develop guidance using proven/reliable solutions, that are brick coordinated, use standard sizes and fitting tolerance allowances
    2. Highlight areas to avoid and design out of housing designs
    3. Explains settlement and weathering implications at openings and provides good practise solutions, such as check reveals
    4. Offer solutions for site and factory fitted options, which becoming increasingly of interest

    Openings are an important design consideration, ensuring these are optimised and designed with suitable allowances/detailing, will ensure they perform as expected over the lifetime of the building.

 

Timber panel
Timber workshop
L&Q Timber Roof Truss

 

Principal OUTCOMES

The AIMCH partners delivered the following principal DFMA Guide outcomes

1
To provide information that helps house designers consider offsite timber panelised MMC.
2

To provide detailed guidance on how best to optimise offsite timber panelised MMC systems.

3
To highlight key design decision points critical to the optimisation of timber panelised MMC
 
4
To flag design constraints that must be considered early and designed out.
5
To act as a starting point and reference document for designers new to offsite timber MMC systems
6
To be user friendly, designed for used by people with a basic understanding of housing design and construction
 

Conclusion

AIMCH has delivered a subject often discussed but difficult to tangibly realise. The DFMA Guide for offsite panelised timber MMC systems, provides a model example to support a step change in attitude, towards industrialised thinking and housing design practises.

The DFMA Guide provides a framework for housing designers to utilise in the creation of DFMA friendly industrialised housing designs of the future.

The DFMA Guide, thought to be one of the first its kind, will be used in the development of AIMCH Industrialised Affordable Housing Designs, embracing Design Standardisation, Product Families and 3D BIM modelling derived within the AIMCH project.

DFMA, Design Standardisation and 3D BIM are very powerful tools to transform housing design and delivery, leveraging learnings from the automotive sector, where these approaches have excelled.   

AIMCH ambition is through the creation and exploitation of future industrialised housing designs AIMCH will fuel a path to delivering more industrialised homes, at an affordable cost.