Construction methods, materials, External Walls Requirements · part of own house, architect/client, BCO raises concerns and avoids errors • Market Share: Few Buildings = Zero +

(21) Timber External Walls 20/12/2007

© NGS 2007 Brian Murphy 1

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

(21) Timber External Walls

CI/SfB (21.1) Load-bearing

(21.3) Non Load-bearing

LSBU Tech & Env 2 Lecture

• Domestic, Small & Medium size buildings

• Construction methods, materials, services and systems

• Timber External Walls

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Performance Requirements

Principles of Element Design

20/12/2007 © NGS 2007 (21) Timber External Walls 4

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Wall Actions

• Gravity: downward pull

• Wind: Motive, Destructive, Penetrative

• Rain: Moisture deposition, penetration

• Snow: Moisture deposition, loading

• Moisture vapour: permeation, condensation, insulation impaired, material degredation

• Sun: Temp variation, thermal movement, heat gains, Chemical decomposition

• Dirt and Dust: infiltration, deposition, surface pollution

• Chemicals: corrosion, disintegration, decomposition

• Sound: Noise nuisance, from within and from without

• Attack: Manual, Ballistics, Bomb Blast

• Thermal: heat loss, radiant coolth, condensation, stack effect

Wall Reactions

• Gravity: Support & restraint

• Wind: rigidity, resilience, sealing, air tightness layers and detailing

• Rain: deflection, impervious skin, absorption and drainage, sealing

• Moisture vapour: resistance, hygroscopicity, permability, breathing, moisture mass

• Snow: deflection, impervious skin, absorption and drainage, sealing

• Sun: movement joints, insulation, shielding, invulnerable materials

• Dirt and Dust: repulsion, exclusion, sheilding, cleaning

• Chemicals: invulnerable materials, exclusion,

• Sound: Insulation, absorption, acoustic mass, separation, isolation,

• Attack: toughness, lamination, edge restraint, edge protection

• Insulating: thermal insulation, thermal mass, U value, G value, cold bridge avoidance/minimisation


• Appearance – Interior and exterior materials

and finishes

• Structural strength and stability– Load-bearing

– Wind resistance

• Weather barrier– Rain, snow, wind, sun,

– dirt dust pollution

• Durability – Moisture resistance, frost,

mould

– Moisture Mass & Hygroscopicity

– Ozone and sunlight degradation

• Thermal Performance– Heat Resistance: loss and gain

– Condensation Avoidance

– Airtightness

– Avoidance of Cold Bridges

– Thermal Mass

• Movement– Structural , thermal, moisture,

Frost

– Chemical


• Acoustic Performance– Resistance, absorption

• Fire Performance– Surface spread of flame

– Fire Resistance

• Security

• Inspection and maintenance– Inside & out

• Pest infestation– Termites,

– Termite Barriers

• Rising damp– Barriers

– Capillary Attraction

– Hygroscopic or Hydrophobic

– Frost action

• Health– Moisture Mass

– Low allergy materials


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Weather Envelope

Absorbent – Repellent – Open Joint Panelled Masonry – Curtain Wall – Rainscreen



03/10/2007 © NGS 2006 Title 1

www.greenspec.co.uk

ZCD: Other Passive Design

ApproachesBrian Murphy (GreenSpec)

Another GreenSpec CPD to download soon Another GreenSpec CPD to download soon

www.greenspec.co.uk05/10/2006 © NGS 2006 Title 1

Wind

Affects on buildings

03/10/2007 © NGS 2006 Title 1

Airtightness& Testing

A94 on-site testingRegulation, Energy loss, Testing, Sealing,

Construction

Another GreenSpec CPD to download soon

Airtightnesswww.greenspec.co.uk

05/10/2006 © NGS 2006 Title 1

Airtightness & Building Elements

NGS GreenSpec CPD



Conduction ConvectionRadiation

Conduction


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Straw Bale Walls

F42 Straw Bale Walling Systems

11/12/2007 © NGS 2006 Title 1

www.greenspec.co.uk

F42 Straw Bale Walls

F42 Straw Bale Walling Systems


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

2 approaches

• Load-bearing bale walls

• Timber framed with bale infill

Straw Bale

• CAT Centre for Alternative Technology

• Published guide

• Amazon Nails: Architect & Builder

• Others: rare experimentation

• Sarah Wigglesworth “any-tech” Architect & Bartlett Lecturer, C4’s Grand Design, small part of own house, architect/client, BCO raises concerns and avoids errors

• Market Share: Few Buildings = Zero +

• NBS published a specification late 2007



Straw Bales

• Rapidly renewable

• Carbon negative: CO2 Sequestration

• Ideally locally harvested

• Seasonal supply

• High density harvester setting

• Large dimensions

• Designs to respect modular bale size

Construction

• DPC at base of wall: avoid water trap

• Load-bearing or framed structure infill

• External walls

• Thick walls: good U value

• Hygroscopic insulation breathing wall

• Lime or earth renders and plasters

• Weather boarding externally

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Refinements

• Bales trimmed at window openings to create sloping jambs to enable greater light penetration through thick walls

• Softer light and low contrast between outdoor light and dark walls

• Chainsaw and scissors

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Hemp-Lime in timber framed Walls


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

2 Approaches

• Timber framed wall (wider spacing)– Temporary formwork to walls

– insitu hemp-lime rammed around posts

• Timber cassette panels– Insitu spray into cassette panel onto back

board

– Spray to thickness (greater than posts)

14/04/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Hemp-Lime Construction

On-line CPD topic

Hemp-Lime ‘Cottage Industry’

• Suffolk Housing Association

• Architects Ralf Carpenter of Modece

• Experimental comparison project

• Significantly out performs conventional walls with better U value

• U and k values are not enough to quantify characteristics, next is G values

• Not fully understood outside small circle

• Potentially CO2 negative: Sequestration

DRAFT

FOR YOUR EYES ONLY NOT TO BE CIRCULATED TO ANYONE ELSE

“Hempcrete” Building Construction with Hemp Composites

A Technical and Design Guide

By

Rachel Bevan and Tom Woolley Disclaimer: The author, publisher, DEFRA and NNFCC do not accept any responsibility, nor liability, in any manner whatsoever for any error or omission, nor any loss, damage, injury, or adverse outcome of any kind incurred as a result of the use of the information contained in this report/book, or reliance upon it. Readers are advised to seek specific professional advice relating to their particular house, construction, project and circumstances before embarking on any building work.

DRAFT

FOR YOUR EYES ONLY NOT TO BE CIRCULATED TO ANYONE ELSE

“Hempcrete” Building Construction with Hemp Composites

A Technical and Design Guide

By

Rachel Bevan and Tom Woolley Disclaimer: The author, publisher, DEFRA and NNFCC do not accept any responsibility, nor liability, in any manner whatsoever for any error or omission, nor any loss, damage, injury, or adverse outcome of any kind incurred as a result of the use of the information contained in this report/book, or reliance upon it. Readers are advised to seek specific professional advice relating to their particular house, construction, project and circumstances before embarking on any building work.



Hemp-lime: Design Guide

• NNFCC National Non-food crops centre

• Funded research project:– Lhoist, Lime Technology Ltd. Hemcrete– Queens University Belfast: Tom Woolley

– NGS GreenSpec: Brian Murphy– Modece: Ralph Carpenter

– Bath Uni: Peter Walker

• Output:– Architects Design Guide– Specification in guide and on GreenSpec site

© reproduced by permission of Lhoist UK

Hemp-lime ‘Industrial scale’

• UK Manufacture

• 3 years of R&D & Marketing

• 50% increase 2006

• 200% increase 2007

• £1.5m turnover

• Growth potential: Exponential

• Market share: minute but growing rapidly

• Many advantages to understand exploit and compete

• Government very interested

Hemp-lime: Violet credentials

• Hemp: CO2 –ve: Sequestration

• Lime: low CO2 (compared to Cement)

• Cement: high CO2

– for fast initial set and long term strength (blockwork standard)

• Aluminium high CO2: add to cement for reaction ‘aircrete’ effect

Hemp-lime

• Green Architects

• Violet Architects with occasional green buildings

Carbon Negative material

• Hemp shiv used as an aggregate and lime as a binder in a limecrete like mix

• Hemp is a rapid growth plant which sequestrates carbon from the atmosphere during photosynthesis whilst growing

• Lime is an adhesive created at lower temperature than cement and is recyclable and reusable

Insitu Constructions

• Light timber frame surrounded by insitu hemp-lime in formwork and rammed

• Backing board with framing, sprayed hemp-lime onto board and built-up to required thickness

• Creates monolithic airtight construction

• Hygroscopic breathing wall

• Ordinary U value with exceptional insulation properties

Blockwork Construction

• Hemp-lime blockwork solid walls

• Hemp-lime blockwork diaphragm walls

• Cavity filled with insitu hemp-lime thermal insulation at a lower density

• Outer skin brickwork for weathering and toughness

• Inner face hemp-lime, lime or clay plaster

• Outer face hemp-lime or lime render



Proprietary Hemp-lime Blocks

• Hemp-lime blocks not quite yet up to BS for concrete blocks minimum 2.8 kN/mm2

• Manufacturer experimenting with recipe

• Adding cement (high embodied energy) for initial set and ultimate strength

• Also adding aluminium (high embodied energy) to cement in mix matrix to obtain foaming function used in ‘Aircrete’ blocks

• Potentially carbon negative material moves towards carbon neutral or carbon positive 20/12/2007 © NGS 2007 (21) Timber External Walls 39

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Diaphragm Walls

• wide cavity walls

• with diaphragm walls linking inner and outer leaf

• Cavity empty or fully filled with insitu insulation grade hemp-lime mix

• Ideally on eco-concrete foundation

Diaphragm Walls


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

MMC Hemp-lime

• System with timber picture frame and insitu hemp-lime infill

• Factory production

• Site Assembly

• External walls infill panel to framed building

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Timber Walls

Timber Constructions

FSC Timber suppliers

• 267 UK sources of FSC certified timber

• Chain of Custody

• Importers

• Growers

• Processors

• Makers

• Stockists

• Project Chain of Custody available

Boron

• Timber preservative treatment

• 1980’s unnecessary retro-treatment

• Up to 3 chemical treatments detected in one piece of timber in attic

• 15 years ago to reject CCA= bankruptcy

• Treatment in decline: – was 50%, now 10% of turnover

• ProBor 75%-80% of its 10% turnover

Timber Stud External WallsPlan section

OutsideBreather Membrane, outer lining (plywood)

Timber Studs, Hydrophobic Thermal Insulation

Vapour Barrier, inner lining (plasterboard)Inside

Timber sections: limited depth before uneconomic or unobtainable



Timber frame walls

Balloon frame Platform Frame

Vapour Barrier/Check

Breather membrane

Eco Concrete Floor

GMV Greenwich Millennium Village Phase 2aTimber stud load-bearing panel walls

GMV Phase 2a 3 storey timber stud panels© NGS

Reduce Waste: Modular design wastes less

• Walter ‘Segal Method’

• Whole component usedfull size no cutting

CAT Centre for Alternative Technology

Robin Hillier ArchitectDiggers Self-build Brighton

Use found materialsBoulders, wild turf roof, gravel margin gutter, rubble wall

Breathing WallsPlan section

OutsideBreather Membrane, Breathing Sheathing Board

Timber Studs, Hygroscopic Thermal Insulation

Vapour permeable Air tightness layer, inner liningInside

Timber sections: limited depth before uneconomic or unobtainable

Brown RoofsCreekside Visitors Centre Deptford London

Timber frame walls

• Balloon frame Platform Frame

Air tightness layer

Breather membrane/sheathing board

Eco Concrete Floor


On-line CPD topic

Breathing Construction




Compound raftersCellulose insulationAcoustic brick floorTimber floor planks

Timber fibre insulationTimber frame wallsTimber batten clad

Construction Resources Showrooms Southwark London

Timber StructureCompound raftersCellulose insulation Acoustic brick floor Timber floor planksTimber fibre insulationTimber frame wallsTimber batten clad


Vapour Balanced ConstructionHygroscopic insulationmaintain their performanceeven when wetVapour and water releasedwhen conditions permitNo need for Vapour BarrierUse vapour permeable construction5:1 ratio vr inside:outsideand an air tightness layer


EVT Enhanced Vapour Transfer

300-600 mm. deep compoundrafters with Cellulose fibreinsulation High thermal mass cellulosefibre insulation boards inwalls and floors


Cellulose FibreWe have a preoccupation withthin walls 300 mm. or lessWhich drives the demand forenergy intensive man-madepetrochemical fossil derivedCFC HCFC HFC HFA foamed plO3 Ozone Depletion Greenhouse Gas Potential300-600 mm. optimuminsulation thickness


Thick walls, roofs and floorsThermal mass:High thermal mass cellulosefibre insulation boards inwalls and floors Acoustic unfired clay bricksin floor constructionadds thermal mass


Thermal Mass



Hygroscopic insulationmaintain their performanceeven when wetVapour and water releasedwhen conditions permitNo need for Vapour Barrier VBUse vapour permeable construction5:1 ratio vr inside:outsideAir Tightness Layer ATL


EVT Enhanced Vapour TransferThermal mass:High thermal mass cellulosefibre insulation boards inwalls and floors


Thermal MassConcrete Frame

Infill panels

Restraint

Restraint

Support

Restraint

Support

Restraint

Support


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Eco-Concrete

• Ordinary Portland Cement replacement– GGBS and PFA

• Aggregate substitution– Secondary aggregates

– Recycled aggregates

– Recycled concrete aggregates

• Engineers permit or restrict their use

• But do little to encourage it

• Embodied energy is low priority

• Market share: 1% of UK concrete is Eco-concrete GMV Phase 2b 4 storey framed & panel infill Greenwich Millennium Village © NGS

Metal Stud External Walls

Metal C Studs, Thermal Insulation, Breather Membrane, inner lining, Vapour Barrier, outer lining

• Egan initiative implemented: prefabrication off-site, simple assembly on site,reduction of site waste

• later on-sitefactory-production

Greenwich Millennium Village Phase 2a

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

Avoid over design of structure around openingsAvoid lack of design: adding additional studs for luckAvoid creating wide cold bridges through insulation

Avoid Waste: chopping thermal insulation rolls

Strength v U Value in external wall



Compound section reduces amount of materials used, weight, cold-bridging

Layering: Services Zone simplify installation & avoid penetrations

Compound Studs ‘I Studs’ to accommodate more thermal insulation

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

MMC Modern Methods of

Construction

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Insulated Structural Floor, wall & roof

PanelsTimber Constructions

Prefabricated external wall panel

Compound Studs ‘I Studs’, inner and outer boards and thermal insulation

Prefabricated external wall panels

Compound studs ‘I studs’, inner and outer boards and thermal insulation

Insulated structural Panels

Roof panels create

Habitable Roof Space

Platform Frame

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Structural Insulated Load-bearing panel roof, wall & floors

Timber ConstructionsPrefabricated external wall panel

SIP Structural Insulated Panel

Prefabricated external wall panel

SIP Structural Insulated Panel



Structural Insulated Panels

Roof panels create


Platform Frame

23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Load-bearing Laminated Timber roof, wall & floors

Timber Constructions


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Load bearing solid timber panel

• Egan Report

• Lean thinking, offsite fabrication

• Carbon sequestration

• CR and EUrban import

• KLM & LinoTec from EU

• Design & Build Contractor

• Established 2002

• £1m turnover 2006/7

• www.eurban.co.uk

Prefabricated external wall panelsoftwood lamina or plywood core option

Load-bearing Structural Timber Panel


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Laminated timbershear walls floors and roofs

Laminated timbershear walls floors and roofs Laminated timber

shear walls floors and roofs



Roof panels create


Platform Frame

Laminated structural timber Panels23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Load-bearing Timber blockwork

Opaque Timber WallsTimber Constructions

Load bearing timber blockwork

• Swiss made

• Radically different construction

• Ideal for DIY and Self-build

• 1 or 2 UK projects

• Tried to include in GMV Greenwich Millennium Village (1300 homes) but not suitable

• CR tried to interest UK manufacture

• CR imported it but no longer

• UK Market share: Zero

Steko “Lego for Self-builders”• Waste from forest thinning

• Low carbon, carbon neutral

• Carbon sequestration

• Dry Construction

• Self-build unskilled construction

• Fast construction (3 day house)

• No waste on site (designed)

• Accommodates services

• Accommodates thermal or acoustic insulation

• Lightweight 6kg (children too)

• Load-bearing (designed to 7 stories)

• Internal and external walls

• 160 mm. modules

STEKOLoad-bearing timber blockworkConstruction Resources Showrooms Southwark London

STEKO

Load-bearing timber blockwork

Attic spaces

Party walls between

flats and terraced or

semi-detached houses

Acoustic details in

Party walls make

heat loss prevention difficult

Party Walls act as heat stacks



23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Resource Efficiency

23/11/2007 12:06 © NGS 2002-2006 Waste At Design Diagrams 1

15/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Design to help Reduce Waste

Easy steps to reduce your shareof the 90 m tonnes of construction and

demolition and excavation waste each year


23/11/2007 © NGS 2006 Title 1

www.greenspec.co.uk

Resource Efficiency:

Timber

Reused wood better than newBedZED Beddington Sutton Architect: Dr Bill Dunster, Reclaim: BioRegional ReCLAIMED © NGS

Reduce Demand

• Don’t cut section from solid if compound is possible

• Reduce solid sections to compound to reduce weight and materials used

Documents

Construction methods, materials, External Walls Requirements · part of own house, architect/client, BCO raises concerns and avoids errors • Market Share: Few Buildings = Zero +