Using Engineered Timber

Advanced Construction Techniques …..Using Engineered Timber

[email protected] [email protected]

Content • Introduction

• Supply

• Raw materials, manufacture process, product range

• Design

• Engineering limits, embodied CO2, prefabrication, fire, connections

• Construction

• Procurement, lead times, supply chain

• Wood futures

• R&D, emerging policy, inspiration

• Case studies

• Open Academy

• City Academy

• Mossbourne Academy

“The best friend of man is the tree. When we use the tree

respectfully and economically, we have one of the greatest

resources on the earth”

Frank Lloyd Wright

Why wood? • Modern method of construction

• Faster, enhanced quality, less waste...Government agenda

• Suits modern ‘skills’ base?

• Sustainability

• Renewable material, full chain of custody

• Lower embodied energy/carbon

• Carbon store

• Lightweight structure

• Versatile

• UK growing reliance on construction imports

• Different...

Why not wood? • Cost

• Currency risk

• Perceived risks

• Fire

• Acoustics

• Supply chain

• Water damage

• Bouncy, noisy floors

• Lack of flexibility

• MMC requires longer lead in

• Lack of competition

• Lack of thermal mass

• Different...


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


• Approximately 20% of worlds land surface covered by trees

• 97% of all softwood used in Europe comes from European forests

• 30% increase in wooded area in Europe between 1990-2000

• Trees are on average 60-80 years old on harvest

• Primary softwoods used for construction are spruce (whitewood) and pine (redwood)

Trees and wood

www.earthobservatory.nasa.gov/Features/ForestCarbon/page1.php

Forest distribution

http://www.earthobservatory.nasa.gov/Features/ForestCarbon/page1.php

Forest distribution

www.earthobservatory.nasa.gov/Features/ForestCarbon/page1.php

http://www.earthobservatory.nasa.gov/Features/ForestCarbon/page1.php

Forest distribution

EU27

Wood stocks:

24 billion m3

Annual growth:

660 million m3

Wood Stocks

EU27

Sawnwood:

95 million m3

Timber in Construction

Timber surplus • EU27 forests are growing year on year

• More than 100 million m3 of growth not harvested

• What could we do with 100 million m3 of wood each year?

• Build 3 million new homes?

• Build 250 million m2 of commercial buildings?

0

5000

10000

15000

20000

25000

30000

1990 2000 2005 2010

Total EU27 growing stock(million m3)

Total EU27 forest area(10,000 ha)

The Forest Stewardship Council (FSC)

Independent non-governmental organisation supported by WWF

www.fsc-uk.org

Pan European Forest Certification Council (PEFC)

Voluntary private sector initiative

www.pefc.co.uk

46 million hectares of managed European forest endorsed

Forests Forever Campaign (FFC)

Independent advisory body initiated by the Timber Trade Federation

www.forestsforever/org.uk

Sustainable timber

• Wood is about 50% carbon (by dry mass) • x 3.67 to convert C to CO2 • Broadleaf forests 100-250 tC per ha • Conifer plantations 70-90 tC per ha • Carbon uptake 4 tC per ha per year in fast

growing stands

Trees and carbon

Trees and carbon

• UK Forestry Commission report

• UK woodland could provide 10% CHG abatement (Scotland already 12%).

• UK ‘forest carbon sink’ reducing from 16mt CO2 in 2004 to 5mt CO2 in 2020.

• Wood fuel potential to save 7mt CO2 in UK.

• Wood substitution potential to save 4mt CO2 in UK.

• Estimated 70mt CO2 stored in timber housing in UK.

Trees and carbon

• 10 billion tonnes pa of engineering materials used globally

• 1.5t person pa, main components are concrete, wood, steel, asphalt, glass, brick

• Concrete is by far the dominant engineering material (factor 10) and responsible for some 5% of global CO2

emissions

Engineering materials

Ref: ‘Materials and the Environment’ Mike Ashby

UK construction materials • 400mt construction materials used annually (2008)

• 1.5mt steel

• 100mt concrete

• 7.5mt timber

• UK has a trade deficit in construction materials/products (2011)

• UK construction products market is £40bn annually

• We import £12bn of construction products annually

• We import £3.5bn from Germany and China

• We export £1.5bn to Ireland and Germany

• We import £650m of steel and export £475m

• We import £110m of cement and export £45m

• We import £135m of rebar and export £50m

• We import £625m of timber

• Price indices history

• www.bis.gov.uk/analysis/statistics/construction-statistics/building-materials

Construction material costs

90.0

100.0

110.0

120.0

130.0

140.0

150.0

160.0

170.0

180.0

2006 2007 2008 2009 2010 2011

Concrete re-inforcing bars

Ready-mixed concrete

Fabricated structural steel

Sawn Wood

Imported Sawn Wood

http://www.bis.gov.uk/analysis/statistics/construction-statistics/building-materials






• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


Cutting technology


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


• Strength graded • C16 and C24 (spruce or pine typically)

• D30 (oak)

• Inherent defects in timber mean factor of safety in region of 3 to 4 used

• Dimensions limited • Typically up to 225mm deep sections

• Kiln drying limits widths typically to 75mm and lengths to 6m

Sawn timber

• Layered/Laminated • Glue laminated timber (glulam)

• Laminated veneer lumber (LVL)

• Cross laminated timber panels (CLT)

• Brettstapel

• Plywood

• Particle • Orientated strand board (OSB)

• Particle board (chipboard)

• Parallel strand lumber (PSL)

Engineered timber

• Glulam • Spruce grades GL24 to GL36

• Lamella thickness typ 40mm

• Stock sizes up to 20cm x 65cm x 13.5m

• Other sizes up to 28cm x 2.2m x 36m

• Glues are melamine resin based.

Engineered timber

• Laminated Veneer Lumber (LVL) • Jumbo plywood made from 3mm thick veneers

• FinnForest – Kerto

• Different lay ups produce boards or beams

• Thickness up to 75mm

• Panel sizes 2.5m x 20m+

Engineered timber

Engineered timber

• Statistics

• 2.95m wide (typical 2.4m)

• 16.5m long (typical 13.5m)

• Typical 50mm to 300mm thick (500mm thk possible)

• Spruce, strength grade C24

• Polyurethane glues (edge glue?)

MMH Binderholz KLH StoraEnso Leno

thk layers thk layers thk layers thk layers thk layers

78 3 66 3 57 3 57 3 51 3

94 3 78 3 72 3 83 3 61 3

95 5 90 3 94 3 97 3 71 3

98 3 100 3 95 5 95 5 81 3

106 3 110 3 128 5 138 5 85 5

118 3 130 3 158 5 161 5 85 11

134 5 100 5 60 3 57 3 93 3

140 5 110 5 78 3 74 3 95 5

146 5 130 5 90 3 83 3 99 3

160 5 147 5 95 3 97 3 105 5

173 5 163 5 108 3 103 3 115 5

184 5 181 5 120 3 112 3 125 5

198 5 203 5 117 5 119 3 135 5

214 7 213 5 125 5 126 3 147 5

214 7 233 7 140 5 95 5 153 5

240 7 248 7 146 5 121 5 165 5

240 7 284 7 162 5 138 5 174 6

258 7 299 7 182 5 150 5 186 6

278 7 341 7 200 5 165 5 189 7

202 7 182 5 201 7

226 7 196 5 207 7

208 7 211 5 219 7

230 7 194 7 231 7

260 7 216 7 240 8

280 7 237 7 252 8

248 8 209 7 264 8

300 8 223 7 273 9

320 8 249 7 285 9

267 7 297 9

296 7

• Cross Laminated Timber

• 15+ European CLT manufacturers?

• KLH 70,000m3

• Stora Enso 120,000m3

• Mayr-Melnhof Kaufmann 40,000m3

• Binderholz 60,000m3

• Finnforest Merk 25,000m3

• Lignotrend 25,000m3

• Total combined output say 350,000m3?

• Equivalent to over 1,000,000m2 of new buildings

• Over 300,000tCO2 sequestered

• Approximately 40,000ha of forest required to support 350,000 m3 of CLT production?

Engineered timber

http://upload.wikimedia.org/wikipedia/commons/0/0a/Isle_of_Wight_UK_locator_map_2010.svg

• Brettstapel • Solid timber panels

• Glued, nailed, screwed or dowelled

• Thickness up to 260mm

• Lengths up to 18m

• Widths up to 1.2m#

• Floor and roof spans up to 10m+

http://www.brettstapel.org/Brettstapel/Home.html

http://www.mm-kaufmann.com/produkte/p1-profideck/

Engineered timber

http://www.brettstapel.org/Brettstapel/Home.html






• Timber cassettes • Sometimes referred to as stressed skin

• Can have insulation integrated (SIPs – structural insulated panels)

• Beams positively connected (glued, screwed, nailed) to a top and/or bottom sheet material. Together the beams (web) and sheeting (flange) make for a highly efficient spanning element

• Can be used as roof or floor elements

• In UK longest recent cassette is 25m roof span over Darlaston Pool in Walsall in 2000.

Engineered timber

• FinnForest/Metsa RIPA panels • Long span cassettes up to 18m long

• Open or closed panels including SIPS

• Depths ranging from 230mm to 650mm

• Roof spans to 18m

• Floor spans 9m+

Engineered timber


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


• Timber is anisotropic • 5 to 10x weaker across the grain (similar to

bundle of straws)

• Affected by moisture • 50% moisture content natural state, 12-

20% in use (hygroscopic)

• 20-40% loss in strength in damp conditions

• Strength • 100N/mm2 defect free, typical 16-

24N/mm2 softwoods used in UK are designed using 6N/mm2

• Direct correlation strength, stiffness and density

• Best at resisting short terms loads, creeps under long term load (approx 40% weaker)

Wood properties

• Strength and stiffness depends on a number of factors:

• Species of timber

• Moisture content of timber

• Duration of load

• Direction of stress within timber

• Defects present in timber

• Slenderness

• Direct correlation between density and strength

Bending parallel to grain N/mm2

Tension parallel to grain N/mm2

Compression parallel to grain N/mm2

Compression perpendicular to grain N/mm2

Shear parallel to grain N/mm2

Modulus of elasticity MEAN N/mm2

Modulus of elasticity MINIMUM N/mm2

Density kg/m3

C16 Spruce

5.3 3.2 6.8 2.2 0.67 8800 5800 370

D40 Oak

12.5 7.5 12.6 3.9 2.00 10800 7500 700

Design

• Load duration factors: • Long term 1.00 (ie dead + live load)

• Medium term 1.25 (ie dead + snow load)

• Short term 1.50 (ie dead + live + snow load)

• Very short term 1.75 (ie dead + live + snow + wind load)

• Moisture content: • 40% to 20% reduction in strength and stiffness for 20%+ moisture content

Design

• Reduces effect of defects

• Glues and mechanical fixing have played important role

• Different types: Layer – Glulam, Plywood, CLT, LVL

Particle – Chipboard, PSL, OSB

Fibre – MDF, Hardboard

0

2

4

6

8

10

12

14

16

18

20

sawn glulam lvl

bending

stiffness

Design


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


Energy input to construction materials

Energy cost represents 10% of

material cost

Energy cost represents 100% of material cost

Energy cost represents 1% of

material cost

Ref: ‘Materials and the Environment’ Mike Ashby

Embodied energy

http://actonco2.direct.gov.uk/actonco2/home.html

• But…..60kgCO2 stored in timber beam

• Timber beam 15kgCO2

• Concrete beam 50kgCO2

• Steel beam 60kgCO2

-250 -200 -150 -100 -50 0 50 100 150 200

steel frame embodied CO2

concrete frame embodied CO2

timber frame embodied CO2

timber frame stored CO2

embodied CO2 (kg/m2)

• Timber CLT frame

• Concrete flat slab frame

• Steel frame and holorib concrete

floor

Embodied CO2 and structure

-650kg CO2 +150kg CO2 +650kg CO2

2500KWhr

1m3

+150kg CO2

+500kg CO2 +700kg CO2

2500KWhr

1m3

+1200kg CO2

1m3 timber

1m3 concrete

CO2 stories for timber and concrete

Environmental product declarations

• Current studies

• Offices 750-1000 kgCO2/m2

• Residential 300-675 kgCO2/m2

• Schools 300-600 kgCO2/m2

• Typically 50% of a new buildings embodied CO2 is in the structure and foundations

• Recent studies indicate that embodied CO2 can represent between 20% to 60% of the whole life CO2 of a building

Embodied CO2…..summary


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


Panelised structures

Crosswall

‘Hybrid’ (steel/CLT)

Loadbearing Facade

Platform construction

Walls/floors Slab/walls


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


• Recent high profile cases • Colindale – during construction

• Fire resistance • Large sections char at rate of 0.6-0.7mm/min

• Oversize timber sections to provide structural integrity during fire (ie timber can be unprotected)

• Spread of flame • For large sections treatment is still required by building

regulations

Fire

CLT CONSTRUCTION DETAILS ...separating floor

CLT CONSTRUCTION DETAILS ...separating wall

CLT CONSTRUCTION DETAILS ...external wall


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


Connections • Connection design critical in timber

structures

• Typically connections determine the section sizes in multiple element structures

• Recent years have seen major advances in fixing technology and automation

• Glued connections strongest and stiffest

• Connections with multiple small fixings (ie nails or screws) are also efficient

Connections

Fixing technology

http://www.sfsintec.biz/internet/sfsinten.nsf/


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


• Organisation & responsibility

• UK currently

Procurement Timber Manufacturer - Detail design - Element layout - Connection design - Fabrication dwgs - Erection sequence - Manufacture - Cutting patterns - Fabrication - Loading sequence - Transport - Erection

Designer(s) - Concept design - Coordination

Client

• Organisation & responsibility

• Mainland Europe currently

Procurement

Timber Manufacturer - Manufacture - Cutting patterns - Fabrication - Transport

Designer(s) - Structural design - Element layout - Coordination - Connection design - Fabrication dwgs

Erector - Erection sequence - Loading sequence - Erection

Client

• Process

Procurement

Final Design - Final design of

Timber Structural Connections Panel layout BWIC Fire Acoustics Fabrication dwgs

- Erection Sequence

Initial Design - Timber vs RC vs

Steel? - Initial design to

establish m3 and m2 of Timber

- Tendered to Timber manufacturers

Construction - Manufacture - Deliver - Erect

Competition Negotiation


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


• Building Magazine Jan 2012

Lead times

• Timber

• Working drawings 4 wks

• Approve working drawings 2wks

• Manufacture 3 wks

• Manufacture 3 wks


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


• UK options

• B&K timber structures

• Eurban

• KLH

• Constructional Timber / Lamisell

• Mainland Europe options

• Metsa (FinnForest)

• Stora Enso

• Mayr Melnhof Kaufmann

• Binderholz

• ……..

• Capacity

• ?????

Supply chain


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


• Recognises that in 2007 forest in England removed 2.9mt CO2, but that this rate is falling.

• Recognises that a major woodland creation scheme is required, target of 10,000 ha per year for 15 years (to remove 50mt CO2 by 2050).

• Woodland creation can also help with employment creation, flood alleviation, water quality improvement and support for wildlife.

• Recognises that woodland resource (timber) needs to be used for fuel and construction.

UK Government and trees

• Gradual increase in building regulations

• Zero carbon new buildings by 2019

• Existing building stock approach uncertain

• IGT report on low carbon construction

• Issued November 2010

• Treasury ‘Green Book’ requirement to

conduct whole life carbon appraisal.

• Industry and Government to develop a

standard method of measuring embodied

carbon for use as a design decision tool.

UK response

Policy & influence

Hackney ‘WoodFirst’ • Hackney Council is consulting on ‘WoodFirst’ planning

policy

• Stadthaus, Bridport House and Mossbourne Academy are all in

Hackney

• Not a ‘Wood Only’ policy!

• ‘Although the Council is keen to promote the benefits of building with

wood, it is not considering a policy that would exclude locally sourced

building materials or prevent the use of other sustainable building

materials in future developments. However, it will take into account

the carbon footprint of a new development to ensure it is in line with

its sustainability policy and the use of structural timber would help to

contribute to this.’

http://apps.hackney.gov.uk/servapps/newspr/NewsReleaseDetails.aspx?id=2437

http://apps.hackney.gov.uk/servapps/newspr/NewsReleaseDetails.aspx?id=2437

• ICE

• The Institute of Civil Engineers (ICE) Civil Engineering Standard Method of Measurement 3 (CESMM3) now includes

carbon and prices for every material and unit of work.

• RICS

• The Royal Institution of Chartered Surveyors (RICS) has established a working group to examine embodied carbon

and to also link it to the New Rules of Measurement (NRM) framework.

• EU

• The European CEN TC 350 series of standards (spring-2011 release) relates to the “sustainability of construction

works”. The series includes a set method for calculating the embodied impacts of construction materials and

projects and a standard on the communication of results (Environmental Product Declarations, EPDs).

• Construction Products Regulation (July 2013)

• Other

• PAS 2050 (UK Carbon Trust), PAS 2060 (BSI)

• ISO/CD 14067, BS 8903:2010

• BES6001 – Responsible sourcing

Life cycle assessment

• Construction Products Directive introduced April 2011

• CE marking is key component providing a ‘fit for purpose’ claim covering:

• Mechanical resistance and stability

• Safety in case of fire

• Hygiene, health and the environment

• Safety and accessibility in use

• Protection against noise

• Energy economy and heat retention

• Major materials manufacturers in UK currently hold CE marking for most of their products (ie

cement, steel and timber)

• Construction Products Regulation will be introduced July 2012

• CE marking will include a new component ‘Sustainable use of natural resources’

• Introduction of CEN/TC 350 – Environmental Product Declaration (EPD)

Construction products regulation

• BES 6001

• RE Global has developed a Framework Standard for the Responsible

Sourcing of Construction Products.

• The scheme provides manufacturers with a means by which their

products can be independently assessed and certified as being

responsibly sourced.

• http://www.greenbooklive.com/search/scheme.jsp?id=153

• 42 companies and products currently registered (manufacturers and

contractors). Mainly concrete industry.

Responsible Sourcing

http://www.greenbooklive.com/search/scheme.jsp?id=153




• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


• 2009 investment in R&D

• £4400m pharmaceutical

• £1100m automotive

• £140m agriculture

• £18m construction

Research and Development

Engineering Alchemy

Polymerised Wood R&D

Wood modification • Improve properties of wood

through chemical and thermal modification

• Potential to improve durability, dimensional stability and strength properties

• Existing examples include Accoya acetylated wood and Thermowood

• Working with Cambridge University on the structural and architectural use of polymerised wood

Submerged bridge at the restored Fort de

Roovere in the Netherlands

50m-span bridge into the city of Sneek in

the Netherlands

Non-treated Wood

Polymerised wood

Polymerisation process

????????

• ??????

• ?????

TIMBER TOWER (R&D CONCEPTUAL PROJECT)


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


Tamedia office building - Zurich by Shigeru Ban Architects

Skelleftea, Sweden

• Mixed use timber building • 141 space multi-storey car park • Cross laminated timber • Fire engineered

Kintai Bashi, Japan


• Supply


• Design


• Construction


• Wood futures


• Case studies

• Open Academy

• City Academy


SmartLife, Cambridge SmartLife, Cambridge

St John Fisher School, Peterborough

Open Academy, Norwich

Norwich academy

• Complex geometry

• Glulam tied arches (radial/’leaning’)

• Flat CLT roof panels – twist!

Roof

City Academy, Norwich

Mossbourne Academy, London

Research and development

Timcrete

Faculty of Education, Cambridge

BGS, Nottingham

Approx 230 residential units, mix of town house and apartments

• 7000m3 of CLT

• 175no. lorry deliveries

• £5,5m CLT contract (supply and erect)

• Potentially 20 week erection using 4 teams

• 5000t CO2 sequestered in the CLT frame

• Europe

• UK manufacture of CLT (Napier University)

• Italy – 9 storey CLT building n site (seismic design)

• Austria – Life Cycle Tower on site (15 storey, hybrid timber and concrete)

• North America

• Three CLT manufacturers

• 30 storey timber tower research project

• Australasia

• CLT manufacture in New Zealand

• Lend Lease CLT residential project (10 Storey)

The Future

References

www.trada.co.uk – Timber Research and Development Association Specific academic resource area

http://www.amazon.co.uk/gp/reader/3764370327/ref=sib_dp_pt

http://www.amazon.co.uk/gp/reader/3764370254/ref=sib_dp_pt

http://www.amazon.co.uk/gp/product/images/3791351818/ref=dp_image_0?ie=UTF8&n=266239&s=books

http://www.trada.co.uk/

Credits

www.trada.co.uk – Timber Research and Development Association Cambridge University Ramboll

http://www.trada.co.uk/

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Using Engineered Timber

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