Schools 300 - 600 ... Advanced Construction Techniques …..Using Engineered Timber simon.smith@
smithandwallwork.com tristan.wallwork@smithandwallwork.
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...
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
Trees and wood • 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)
Forest distribution
www.earthobservatory.nasa.gov/Features/ForestCarbon/page1.php
Forest distribution
www.earthobservatory.nasa.gov/Features/ForestCarbon/page1.php
Forest distribution
Wood Stocks
EU27 Wood stocks: 24 billion m3 Annual growth: 660 million m3
Timber in Construction
EU27 Sawnwood: 95 million m3
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?
30000 25000 20000 15000
Total EU27 growing stock (million m3)
10000
Total EU27 forest area (10,000 ha)
5000 0
1990
2000
2005
2010
Sustainable timber 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
Trees and carbon • • • • •
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.
Engineering materials • 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
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
Construction material costs • Price indices history •
www.bis.gov.uk/analysis/statistics/construction-statistics/building-materials
180.0 170.0
160.0 150.0 Concrete re-inforcing bars 140.0
Ready-mixed concrete Fabricated structural steel
130.0
Sawn Wood Imported Sawn Wood
120.0 110.0 100.0 90.0 2006
2007
2008
2009
2010
2011
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
Cutting technology
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
Sawn timber • 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
Engineered 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+
MMH thk layers 78 3 94 3 95 5 98 3 106 3 118 3 134 5 140 5 146 5 160 5 173 5 184 5 198 5 214 7 214 7 240 7 240 7 258 7 278 7
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?)
Binderholz thk layers 66 3 78 3 90 3 100 3 110 3 130 3 100 5 110 5 130 5 147 5 163 5 181 5 203 5 213 5 233 7 248 7 284 7 299 7 341 7
thk 57 72 94 95 128 158 60 78 90 95 108 120 117 125 140 146 162 182 200 202 226 208 230 260 280 248 300 320
KLH layers 3 3 3 5 5 5 3 3 3 3 3 3 5 5 5 5 5 5 5 7 7 7 7 7 7 8 8 8
StoraEnso thk layers 57 3 83 3 97 3 95 5 138 5 161 5 57 3 74 3 83 3 97 3 103 3 112 3 119 3 126 3 95 5 121 5 138 5 150 5 165 5 182 5 196 5 211 5 194 7 216 7 237 7 209 7 223 7 249 7 267 7 296 7
Leno thk layers 51 3 61 3 71 3 81 3 85 5 85 11 93 3 95 5 99 3 105 5 115 5 125 5 135 5 147 5 153 5 165 5 174 6 186 6 189 7 201 7 207 7 219 7 231 7 240 8 252 8 264 8 273 9 285 9 297 9
Engineered timber • 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 • 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 • 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+
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
Wood properties • Timber is anisotropic •
5 to 10x weaker across the grain (similar to bundle of straws)
• Affected by moisture • •
50% moisture content natural state, 1220% in use (hygroscopic) 20-40% loss in strength in damp conditions
• Strength •
• •
100N/mm2 defect free, typical 1624N/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)
Design C16
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
5.3
3.2
6.8
2.2
0.67
8800
5800
370
12.5
7.5
12.6
3.9
2.00
10800
7500
700
Spruce
D40 Oak
•
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
Design
•
Load duration factors: • • • •
•
Long term Medium term Short term Very short term
1.00 1.25 1.50 1.75
(ie dead + live load) (ie dead + snow load) (ie dead + live + snow load) (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
20 18 16 14 12 10 8 6 4 2 0
bending stiffness
sawn
glulam
lvl
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
Energy input to construction materials Energy cost represents 100% of material cost
Energy cost represents 10% of material cost
Energy cost represents 1% of material cost Ref: ‘Materials and the Environment’ Mike Ashby
Embodied energy
Embodied CO2 and structure • Timber beam 15kgCO2 • Concrete beam 50kgCO2 • Steel beam 60kgCO2 • But…..60kgCO2 stored in timber beam
embodied CO2 (kg/m2) • Timber CLT frame
timber frame stored CO2
• Concrete flat slab frame • Steel frame and holorib concrete floor
timber frame embodied CO2
concrete frame embodied CO2
steel frame embodied CO2
-250
-200
-150
-100
-50
0
50
100
150
200
CO2 stories for timber and concrete 2500KWhr 1m3
1m3 timber -650kg CO2
+150kg CO2
+650kg CO2
+150kg CO2
2500KWhr 1m3
1m3 concrete +500kg CO2
+700kg CO2
+1200kg CO2
Environmental product declarations
Embodied CO2…..summary • 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
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
Panelised structures Loadbearing Facade
Crosswall
‘Hybrid’ (steel/CLT)
Platform construction Walls/floors
Slab/walls
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
Fire • 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
CLT CONSTRUCTION DETAILS ...separating floor
CLT CONSTRUCTION DETAILS ...separating wall
CLT CONSTRUCTION DETAILS ...external wall
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
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
Connections • Glued connections strongest and stiffest • Connections with multiple small fixings (ie nails or screws) are also efficient
Fixing technology
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
Procurement Timber Manufacturer
• Organisation & responsibility •
-
UK currently
Designer(s) -
Concept design Coordination
Client
Detail design Element layout Connection design Fabrication dwgs Erection sequence Manufacture Cutting patterns Fabrication Loading sequence Transport Erection
Procurement • Organisation & responsibility •
Mainland Europe currently
Timber Manufacturer Designer(s) -
Structural design Element layout Coordination Connection design Fabrication dwgs
-
Manufacture Cutting patterns Fabrication Transport
Client
Erector -
Erection sequence Loading sequence Erection
Procurement • Process
Competition
Negotiation
Initial Design
Final Design
-
-
-
-
Timber vs RC vs Steel? Initial design to establish m3 and m2 of Timber Tendered to Timber manufacturers
Final design of Timber Structural Connections Panel layout BWIC Fire Acoustics Fabrication dwgs
-
Erection Sequence
Construction -
Manufacture Deliver Erect
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
Lead times • Building Magazine Jan 2012
• Timber •
Working drawings 4 wks
•
Approve working drawings 2wks
•
Manufacture 3 wks
•
Manufacture 3 wks
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
Supply chain • UK options •
B&K timber structures
•
Eurban
•
KLH
•
Constructional Timber / Lamisell
• Mainland Europe options •
Metsa (FinnForest)
•
Stora Enso
•
Mayr Melnhof Kaufmann
•
Binderholz
•
……..
• Capacity •
?????
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
UK Government and trees • • • •
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 response • 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.
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
Life cycle assessment • 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
Construction products regulation • 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)
Responsible Sourcing • 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.
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
Research and Development • 2009 investment in R&D •
£4400m pharmaceutical
•
£1100m automotive
•
£140m agriculture
•
£18m construction
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
50m-span bridge into the city of Sneek in the Netherlands
Submerged bridge at the restored Fort de Roovere in the Netherlands
Polymerisation process Non-treated Wood
Polymerised wood
???????? •
?????? • ?????
TIMBER TOWER (R&D CONCEPTUAL PROJECT)
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
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
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
SmartLife, Cambridge
SmartLife, Cambridge
St John Fisher School, Peterborough
Open Academy, Norwich
Norwich academy
Roof
• Complex geometry • Glulam tied arches (radial/’leaning’) • Flat CLT roof panels – twist!
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
The Future • 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)
References www.trada.co.uk – Timber Research and Development Association Specific academic resource area
Credits www.trada.co.uk – Timber Research and Development Association Cambridge University Ramboll
