GBE CPD MMC Modern Methods Of Construction

MMC Modern Methods of Construction CPD

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MMC Modern Methods of Construction
© 2007 – 2020
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Definition

‘a broad range of processes that aim to produce more, better quality homes in less time.
The definition is categorised in terms of products:
Panellised, volumetric, hybrid and other methods,
and may involve off site manufacturing.’
NAO (National Audit Office)

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Unintended Consequences MMC

Building more housing rapidly to solve housing crisis using the wrong materials will add to:
‘Carbon Burp’ if carbon intensive materials (Plastics) are used or
‘Energy Burp’ is using energy intensive materials (Metals and mineral fibres) are used
let alone other issues (described below)

Considerations

Many timber-based methods as well as metal or concrete
Insulating, thermal bridge free, airtight construction, Low Embodied Carbon, Low energy demand in use, no overheating, Bio-based v petro-chemical construction
Better buildings than business as usual, lowering prices of home ownership or more business as usual profiteering at the expense of customers?
‘Need for speed’ by Government, at the expense of getting it wrong, again.
Quality of MMC for manufacturers or quality of building for users?

Offsite process and smart Tech influence on Construction

Improvements in competency
Tolerance (On-site inaccuracy accommodation)
Modular design (As bought material sizes) and waste minimisation
Design for construction/assembly and deconstruction/reconstruction for second life applications
BIM with CAD CAM capability
BIM with clash detection,
BIM with materials intelligence
BIM with energy and comfort modelling apps
Logistics Software and logistics of supply to sites

MMC Format:

Framed, Infill, Pod, Panel, Modular, stacking assembly and joining techniques.
Modular acknowledging the size of materials to reduce off-cut waste
Modular to enable reuse at end of first life.

Building Performance:

Strength, Fire, Acoustic, Thermal, Thermal bridging, wind and air tightness, Moisture integrity
MMC cannot be looked at in isolation from performance and how the building will be serviced (temperature, humidity, etc. control)
And if it is to be Vapour open or Vapour closed construction and materials choices subsequently

Forms of off-site construction and delivery

Production benefits associated with off site construction including modular construction, factory construction, automation and robotics, and 3D printing

Pods and Modules; How installed

Consider how pods and modules are inserted into framed construction, into or onto floor thickness,
interface with preceding and following trades,
maintaining all performance integrity, connecting to services and finishing off the connections and accesses.

Modules: How assembled

Consider how modules are assembled and maintaining thermal bridge free construction
Consider how modules attach thermally-broken from and to:
- any other structure: frames;
- and to secondary elements: Stairs, landings, balconies

Framing and thermal bridges

Needs to consider framing/non-framing methods of panel production,
alternative framing materials and potential for thermal bridging,
impact of strengthening at edges and openings on the increases in thermal bridges.

Acoustics

Consider acoustic performance of external fabric with various thermal insulation choices

Insulation choices

Need to consider insulation choices for:
- winter heating (normal) and
- summer cooling (essential with MMC) and risks of overheating or
- risk of high energy/carbon over life of building with retrofitting ‘comfort cooling’ air conditioning.

Overheating

Consider top floors and single aspect
to be able to stay cool in summer overheating potential
Security,
smells,
noise and night time noise in use,
windows and vents

Panel/Joint and Psi values

Needs to consider insulation material choices and potential thicknesses
and (thermal bridge psi values increase in thicknesses.

Insulation thickness: on Module Size

Thickness of panels size
impact on Modular and Panels on the transport implications.

Joints: Air and Wind Tightness

Consider panel and semi-modular assembly and wind and air tightness
- regimes and
- details of any Penetrations
- Including Services

Integrating Services

Integrating services
rewiring during life,
wiring across junctions and joints,
adding new services during use

Comparison

All or most of the site issues move to the factory
or duplicate the issues on site and in the factory
- –Waste,
- –H&S,
- –Wet trades,
- –Tolerances,
- –Factory Dry, weather-free conditions
- –Skills shortages,
- –Training to Approved status,
- –No time to care

Management need to manage

Management, Supervision,
Modern and Innovative methods need Trade Toolbox talks

Impact of off-site construction on

assembly,
time on-site,
quality,
waste minimisation,
Safety

Social, economic, environmental and cultural factors:

Consider:
- –Bio-based methods of construction: solid wood, CLTP, LTF, SIPS, ISPS.
- –Bio-based insulation, consider Embodied Carbon. Operational Carbon, Whole Life Carbon, Whole Life Costs, Whole Life carbon Costs.
- –Plastic free construction.
- –Products accessories and systems on the market.

Different production models

Trade schools and skilling for the tasks.
Wet or dry trades,
pre-drying,
curing,
performance optimisation

Logistics

Traffic, overnight haulage, preplanning route, consolidation yard, final delivery, cranes, handling,

On-site installation

Stacking, interlocking, guiding technology or inserting into existing, sliding, inserting from cranes,
Safety issues
Tolerances, assembly creep, replacing intermediate units/panels, design for assembly, designing for deconstruction, Servicing, integrity proofing,
Energy performance
Building Regulations and SAP or SBEM
- –are not good enough for Climate Emergency

%%% More work to do

Consider:

–Passivhaus & EnerPHit
–AECB CarbonLite,
–LETI,
Users Expectations
Better informed public are expecting better
If MMC want to show the Construction Industry how to do things in a competent manner, then they need to address everything.
Retrofitting MMC
Retrofitting inadequate MMC will be impractical and makes no financial sense.
I would want to sue the MMC sector for ignoring the obvious and sue them for ignoring climate change and for creating overheating buildings.
Comfortable with no overheating
Passivhaus energy standards are based in comfort conditions
Economy/market
Viability of main electricity and carbon intensity to serve the MMC services and maintain a low carbon solution
Procurement
MMC manufacturer as contractor and site works as sub-contractor
User/stakeholder requirements.
PII risk free
Competent, condensation free, mould free, overheating free, no fire risk, no unsellable homes,
Detailed Analysis
MMC
Offsite Configurations:
Volumetric,
- –Modular
Domestic: parts of flats or houses
Motels: Bedroom bath corridor bath bedroom
- –Podular
Bathrooms
Kitchens
Plant rooms
Freezers
Panellised: Walls, floors, roofs, partitions
Turn key solutions

–Fast food chains: Complete fit out at factory

Opportunities:
Off-site factory production
On-site in factory conditions
Waste minimisation in factory, minimal site waste
No surpluses delivered to site, used in factory
Packaging waste onsite minimisation
Efficient site work

–Unhindered ground works

–Servicing connection and completion

Lean Construction
Aim to minimise waste in all its forms

–Management time

–Labour time

Factory production can exploit this well

–Production line efficiencies

–Trade or task Specialisation

–JIT deliveries

Lean Gone Wrong
But lean is being misinterpreted and going wrong, seriously wrong

–Masonry

–Wiring

Design Issues:
Factory Production
Created to standard/design sizes

–Ignore site reality

–Base inaccurate setting out?

Site/Factory tolerances

–sometimes things go wrong

Site operative idea of tolerances don’t match factory
Wasted on site if wrong size
Design Issues:
Site production
Create site factory under canvas
When offered up, if wrong size, rework and reinstall
Potentially less waste
Design Issues: Insulation
Rarely have any thermal mass or decrement delay
Use thin high embodied carbon and embodied energy insulating materials
Gappy insulation > Performance Gap
Gaps between units? Heat loss
Design Issues: Installation
Big strong operatives may damage fragile parts
Site operative idea of tolerances don’t match factory
Wasted on site if wrong size
‘Helping hand’ supports permit adjustment

–Potentially one man operation

Procurement:
High % of Costs: are in the Modules
Low % of Costs: Site works
Profits for attendance and preliminaries by Main Contractor if % become large
Site Works Contractor/Operatives may become a subcontractor of the Modular manufacturer

–More control over site setting out and tolerances

Site Preparation:
Similar to Normal sites
All services in and wastes out
Landscape: Hard, soft and wet
May include reclaim and reuse of water
May include permeable pavement
Bases for MMC need to be accurate
Logistics Issues
Volumetric:

–Transporting lots of fresh air

–Avoided by panellised

Just in time delivery

–Needs buffer park-up place near site

Road closures

–Expensive crane hire

MMC Elemental Assemblies
Materials and methods
Light Timber Frame (LTF)
Light Metal Framed (LMF)
Prefabricated panel construction
Metal Stud External Walls
Greenwich Millennium Village Phase 2a
Egan initiative implemented:
prefabrication off-site, simple
assembly on site,
reduction
of site waste
later on-site
factory-production
Metal frame walls
Balloon frame Platform Frame
Concrete Frame

Infill panels

Curtain wall

Factory Prefabrication:
Conditions ensure no deterioration
No mud or cement splashes
No rain to spoil
Use of all the materials supplied
Reusing until all is gone
Virtually no waste
Compound Studs ‘I Studs’ to accommodate more thermal insulation
MMC Modern Methods of Construction
Opaque Timber Walls Timber Constructions
Compound Studs ‘I Studs’, inner and outer boards and thermal insulation
Compound studs ‘I studs’, inner and outer boards and thermal insulation
Insulated structural Panels

Roof panels create

Habitable Roof Space

Platform Frame

SIP Structural Insulated Panel
SIP Structural Insulated Panel
Structural Insulated Panels

Roof panels create

Habitable Roof Space

Platform Frame

Load-bearing Cross Laminated Timber Panel walls (CLTP)
Opaque Timber Walls Timber Constructions
Load-bearing Structural Cross Laminated Timber Panel
Cross Laminated Timber Panel
shear walls floors and roofs
Cross Laminated timber Panels

Roof panels create

Habitable Roof Space

Platform Frame

Load-bearing Timber blockwork
Opaque Timber Walls Timber Constructions

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Off-site
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