Tall Wood Takes a Stand – Proven to be Safe and Cost Effective

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Tall Wood Takes a Stand – Proven to be Safe and Cost Effective

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The growing awareness of the environmental benefits of wood combined with advances in wood technology and manufacturing have aligned to make tall wood buildings not only possible but safe and cost......

The growing awareness of the environmental benefits of wood combined with advances in wood technology and manufacturing have aligned to make tall wood buildings not only possible but safe and cost effective. While the increasing number of code-approved, light-frame wood construction projects reaching five and even six stories has helped North American building professionals raise their comfort level with wood, a number of forward-looking architects, engineers, and developers are looking beyond six stories.
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  • There’s a quiet shift on the horizon—one that has the potential to change North American skylines.

    Heightened awareness of the environmental benefits of wood combined with advances in wood technology and manufacturing have aligned to make tall wood buildings not only possible but safe and cost effective. 

    While the increasing number of code-approved, light-frame wood construction projects reaching five and even six stories has helped North American building professionals raise their comfort level with wood, a number of forward-looking architects, engineers, and developers want more. 
     
    With all of these attributes, wood is well positioned as a key component of environmentally superior structures. Yet, early efforts to promote green construction resulted in highly variable treatment of wood in green building rating systems—which, at the time, were largely based on long lists of prescriptive standards, typically focused on single attributes such as recycled content. Such variability can still be seen in many of the green building programs in use today. However, these systems are increasingly moving away from prescriptive standards and toward reliance on systematic, multi-attribute assessment of building products, assemblies, and completed structures through life cycle assessment (LCA). The result is greater uniformity between programs and far greater robustness in evaluation, both of which serve to leverage the environmental advantages of wood.
     
    Sources
     
    1. Werner, F. and Richter, K. 2007, Wooden building products in comparative LCA: A literature review; A Synthesis of Research on Wood Products & Greenhouse Gas Impacts, FPInnovations, 2010
     
    2. Wood and Human Health, FPInnovations; Consumer Visual Evaluation of Canadian Wood Species, FPInnovations, D. Fell, 2002; Appearance Wood Products and Psychological Wellbeing, Society of Wood Science and Technology, Rice J., Kozak Robert A., Meitner Michael J., and Cohen David H., 2006
     
    3. Wood and Human Health, FPInnovations; C. Kelz1,2 Grote V.1,2, Moser M. 1,2 Interior wood use in classrooms reduces pupils’ stress levels, 1Institute of Physiology, Medical University of Graz, Austria; 2 HUMAN RESEARCH, Institute for Health, Technology and Prevention Research, Weiz, Austria; Human Response to Wood, Architectural Record CEU, reThink Wood
  • reThink Wood sponsors this program provided by McGraw-Hill Publishers. As an AIA-approved program, the information presented is not intended to be an approval or endorsement by the AIA of any product, material, or method of construction.

    Credit earned upon completion of this program will be reported to AIA for AIA members. Certificates of completion are available for self-reporting and record-keeping needs.

    Questions related to the information presented should be directed to reThinkWood via email—info@rethinkwood.com—upon completion of this program.
  • This program is protected by U.S. and international copyright laws. Reuse of any portion of this program without written consent from reThink Wood is prohibited.

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  • When it was completed in 2011, this eight-story structure formed the largest timber-built apartment block in the world. Built using a conventional platform-based CLT system, the structure included 41 new homes in two joined blocks; one eight-story building and the other five stories. All elements from the ground floor up were of CLT, including the elevator shaft. As is typical of these buildings, the below-ground level was of reinforced concrete but the ground floor was CLT . 
     
    Developers chose to use wood for Bridport House for several reasons: structural capabilities of CLT, speed of construction, and environmental advantages. 
     
    The project was built over an old sewer line that runs through London; the line is big enough to drive a double-decker bus through but could not sustain the loads of a heavy concrete building above. Wood’s light weight allowed the developer to maximize use of the site while still meeting below-ground requirements. In fact, the structure was twice as high as the previous building, while the weight increased by only 10 percent. 
     
    On-site assembly took just 12 weeks, primarily because the CLT panels were prefabricated off-site and then lifted into place. EURBAN , the project’s timber engineer, estimates that on-site assembly time was 50 percent faster than conventional reinforced concrete. 
     
    The environmental benefits of using wood for Bridport are also noteworthy. If the building had been constructed of reinforced concrete, manufacturing of the materials would have resulted in an additional 892 tons of carbon into the atmosphere; that’s equivalent to 12 years of the operational energy required to heat and light all the dwellings at Bridport House. When the carbon stored in the timber structure is added to the avoided greenhouse gas emissions, the total carbon benefit is 2,113 tons—equivalent to 29 years of operational energy. Plus, because of the thermal benefits afforded by a CLT building system, the structure’s airtightness measured three times better than that required by local Building Regulations.6 
     
    Source:
    6 Bridport House Case Study, Willmott Dixon, 2011
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  • Rising 10 stories, Forté is Australia’s first CLT building and first high-rise timber apartment. At its time of completion, it was the tallest timber apartment in the world. 
     
    The developer and contractor, Lend Lease, used a conventional platform-based CLT system to build the $11-million project, which includes 23 apartments and four townhouses. Speed of construction was a huge benefit to the global company; Lend Lease estimated that they cut construction time by 30 percent. Construction began in February 2012; they began installing the CLT in May and completed the wood portion of the structure in August. 
     
    While they chose CLT in part because it met safety and quality requirements, Lend Lease cites the environmental benefits as their primary reason for building the tall building out of wood. Forté was expected to be the first 5 Star Green-Star As Built-certified residential building in Australia. And by using CLT, the structure will reduce CO2 equivalent emissions by more than 1,400 tons when compared to concrete and steel—the equivalent of removing 345 cars from Melbourne’s roads for a year.7 
     
    Mark Menhinnitt, chief executive officer for Lend Lease’s Australian business, says, “CLT will transform the construction industry by introducing a more efficient and environmentally friendly construction process that has never been undertaken in Australia before. By adopting green technologies, materials and construction processes, we are closer to creating livable, sustainable cities that are climate positive.” 
     
    Lend Lease reported that costs to build Forté with CLT were comparable with that of using concrete. Going forward, they said they plan to develop 30 to 50 percent of their Australian apartment projects using CLT . 
     
    Source:
    7 Forté Case Study, Lend Lease, 2012
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  • Applewood Pointe at Langton Lake is a senior housing project in Roseville, Minnesota. The 48-unit four-story wood structure had a one-hour fire rating; it was sited over a three-hour rated pre-cast concrete parking garage, for a total of 123,964 square feet. According to Roger Johnson with JSSH Architects of Minnetonka, Minnesota, wood-frame was the most cost-competitive option, at $80 per square foot complete. 
  • Emory Point, a mixed-use project near Emory University in Atlanta, Georgia, is a 442-unit project that includes one five-story wood-frame building over slab-on-grade and three four-story wood-frame buildings over one-story concrete podiums. Brad Ellinwood, P.E., of Ellinwood + Machado Consulting Structural Engineers, says they considered a number of systems but wood was the most economical. When they evaluated the cost of the structural frame portion only, the wood design cost approximately $14 per square foot compared to $22 per square foot for a 7-inch post-tensioned concrete slab and frame. The huge wood-frame project was completed in just over a year, which provided additional cost savings. 
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  • When Cree GmbH developed their LifeCycle Tower system, they knew the best way to sell the concept was to prove its viability. With the building envelope and floors erected in March 2012, the eight-story LifeCycle Tower ONE in Austria does just that. 
     
    The LCT system does not use CLT. While the elevator core of the building could have been made from either concrete or wood, the 17,000-square-foot LCT ONE started with a concrete podium and core, followed by a wooden post system supporting hybrid slabs. 
     
    The engineered hybrid slabs were fabricated off site. Wood beams are laid horizontally inside the steel formwork, metal reinforcement is attached to the wood members and then the concrete is poured to produce the slab. Cree’s Tahan says that, for a current project in Austria, they are producing up to three slabs per day in their facility. 
     
    Non-load-bearing wood-framed curtain wall panels were fabricated off site to include insulation, sheathing and windows, with taped joints for improved energy performance. These exterior walls were attached to the load bearing glulam posts. The posts had high-strength metal tubes inserted on top and metal plates with pins attached to their bottom. These prefabricated elements were shipped to the site and installed quickly, with the pin at the bottom of a post inserted into the tube in the post below. Prefabrication resulted in controlled costs and quick construction; LCT ONE’s carpenters erected the eight-story building in just eight days—one story per day. 
     
    Wood’s environmental and structural benefits were key considerations for LCT ONE. The wood-framed curtain walls were engineered to maximize R-value and reduce thermal bridging, allowing the building to meet PassivHaus standards. The wood post/slab configuration is also earthquake resistant and resists fire damage without losing strength because the reinforcing steel is encased inside the concrete. The building’s façade was constructed of composite metal, installed on site to prevent damage, while the visible wooden supporting structure was left exposed inside. 
     
    LCT ONE showcased Cree GmbH’s models of sustainability and energy efficiency, improved CO2 footprint, efficient factory-produced components and costs savings from a shorter construction schedule. 
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  • Thank you for your time. Visit www.rethinkwood.com for more information, or email info@rethinkwood.com with any questions.

Transcript

  • 1. Tall Wood Takes a Stand Tall wood buildings proven safe and cost effective Earn 1 AIA/CES HSW learning unit CEU Publish Date: December 2012 PhotocourtesyofCreeBuildings,Inc.
  • 2. Best Practices reThink Wood sponsors this Continuing Education Unit provided by McGraw-Hill Publishers. This course is registered with AIA CES for continuing professional education. As such, it does not contain content that may be deeded or construed to be an approval or endorsement by the AIA of any materials of constructions or any manner of handling, using, distributing, or dealing in any material or product. Credit earned on completion of this course will be reported to AIA CES for AIA members. Certificates of completion are available for self-reporting and record-keeping needs. Questions related to the information presented should be directed to reThinkWood upon completing this program. AIA Provider Number: K029 AIA Course number: K1212C AIA Credit: 1 HSW/SD hour
  • 3. Copyright Materials This presentation is protected by U.S. and international copyright laws. Reproduction, distribution, display and use of the presentation without written permission of reThink Wood is prohibited. © 2014, reThink Wood, www.rethinkwood.com
  • 4. Learning Objectives  Recognize that mid-rise (six to 12 stories) and tall buildings (up to 30 stories) can be safely, efficiently, and economically built using mass timber construction techniques.  Discuss the different types of design approaches to mass timber construction for tall wood buildings.  Explain the similarities and differences between the structural composite panel and lumber products that allow building professionals to design and construct tall wood buildings.  Distinguish the differences between design approaches to accessing the acceptable structural passive fire protection measures in a mass timber building.
  • 5. Table of Contents Section 1 Tall Wood Building Report Section 2 The Inspiration Behind Tall Wood Buildings Section 3 What is Mass Timber Construction? Section 4 Why Use Wood in Tall Structures
  • 6. TALL WOOD BUILDING REPORT SECTION 1
  • 7. Why Wood?  Cost-effective  Renewable resource with lower manufacturing greenhouse gas emissions  Lowest embodied energy among major building materials  Negative carbon footprint due to wood’s carbon storage Photo courtesy of naturallywood.com
  • 8. How Mass Timber Offers a Safe, Economical, and Environmentally Friendly Alternative for Tall Building Structures The Case for Tall Wood Buildings Study by Architect Michael Green of mgb and J. Eric Karsh from Equilibrium Consulting Inc. Photo courtesy of Cree Buildings, Inc.
  • 9. Tall Wood Report We must find solutions for our urban environments that have a lighter climate impact than today’s incumbent major structural materials. The Tall Wood report is a major step in that direction. Indeed, it introduces the first significant challenge to steel and concrete in tall buildings since their adoption more than a century ago. - Michael Green, Architect mgb “ ”
  • 10. THE INSPIRATION BEHIND TALL WOOD BUILDINGS SECTION 2
  • 11. Environment Photo courtesy naturallywood.com. “Architects are realizing that the old ways of doing things will not continue to work; we are ruining the environment. Because of this, we’re now seeing an industrial revolution for wood. Wood is a renewable product that can do much more than we have yet asked of it.” - Nabih Tahan, AIA,with Cree Buildings, Inc.
  • 12. Advancements in Mass Timber Building Techniques  Cross laminated timber (CLT)  Laminated veneer lumber (LVL)  Laminated strand lumber (LSL)  Glued laminated timber (Glulam) Rendering courtesy of mgb
  • 13. Cross Laminated Timber (CLT)  Engineered wood panel  3, 5 or 7 layers of dimension lumber oriented at right angles to one another then glued to form structural panels  Exceptionally strong, dimensionally stable and rigid Photo courtesy of naturallywood.com
  • 14. Laminated Veneer Lumber (LVL)  Thin wood veneers bonded together  Wood grain oriented parallel to the length of the member  Predictable structural performance and dimensional stability  Free from warping and splitting Photos courtesy of naturallywood.com
  • 15. Laminated Strand Lumber (LSL)  Engineered structural composite lumber  Thin chips or strands of wood up to 6” in length glued under pressure  Wood grain oriented parallel to the length of the member, then machined to finished sizes  Strong when face- or edge- loaded Photo courtesy of naturallywood.com
  • 16. Glue Laminated Timber (Glulam)  Composed of individual wood laminations  Bonded together with durable, moisture-resistant adhesives  Grain runs parallel with length of member  Used horizontally as a beam or vertically as a column Photo courtesy of naturallywood.com
  • 17. Bridport House Location: Hackney (London), UK Architect: Karakusevic Carson Architects Contractor: Willmott Dixon Group Timber Engineer: EURBAN Year of completion: 2011 Developers chose to use wood for Bridport House for several reasons: structural capabilities of CLT, speed of construction, and environmental advantages. When it was completed in 2011, this eight-story structure formed the largest timber-built apartment block in the world. Photo courtesy of Karakusevic arson Architects
  • 18. WHAT IS MASS TIMBER CONSTRUCTION? SECTION 3
  • 19. Mass Timber Construction  Uses large prefabricated wood members such as CLT, LVL and LSL for walls, floors and roof  Glulam for beam and columns applications  Engineered for strength Photo courtesy of naturallywood.com
  • 20. CLT Panels  Resists high racking and compressive forces  Cost effective for multi-story and long-span diaphragm applications Photo courtesy of Land Lease At 10 stories, Forté in Melbourne, Australia, was the tallest timber apartment in the world when it was completed in 2012.
  • 21. LifeCycle Tower  Prefabricated hybrid wood / concrete slab system  Central stiffening core for elevator, stairs and shafts  Glulam posts on exterior  Structures up to 30 stories LifeCycle Tower ONE’s prefabricated hybrid wood / concrete slab system is supported by a central stiffening core on the interior and by glulam posts on the exterior. Photo courtesy of Cree Buildings Inc.
  • 22. Finding the Forest Through the Trees (FFTT) Uses mass timber panels and glulam as primary structural members to achieve potential building heights of up to 30 stories  ‘Strong column-weak beam’ balloon-frame approach  Building performs well under wind and seismic loading conditions  Structures up to 30 stories  Quick installation Rendering courtesy of mgb
  • 23. WHY USE WOOD IN TALL STRUCTURES SECTION 4
  • 24. Environmental Benefits Grows naturally and is renewable Photos: naturallywood.com
  • 25. Forté Location: Melbourne, Australia Architect / Contractor / Developer: Lend Lease Year of completion: 2012 Rising 10 stories, Forté is Australia’s first CLT building and first high-rise timber apartment. Lend Lease cites the environmental benefits as their primary reason for building the tall building out of wood. Speed of construction was a huge benefit to the global company – with an estimated cut in construction time of 30 percent. Photo courtesy of Lend Lease
  • 26. LCA and Wood  Wood outperforms other materials in terms of embodied energy, air and water pollution, and greenhouse gas emissions. Source: Data compiled by the Canadian Wood Council using the ATHENA EcoCalculator with a data set for Toronto, Canada.
  • 27. The Carbon Connection As architects, we have to ask ourselves: Is there a material that minimizes or eliminates carbon in the environment? -- Michael Green, MAIBC, AIA, MRAIC Michael Green Architecture “ “ Prince George Airport British Columbia Architect: mgb Photo: mgb
  • 28. Cost Competitive  Cost competitive up to 30 stories  Different configuration choice offers flexibility  Installed much quicker leading to faster occupancy Photo courtesy of Land Lease Development company Lend Lease estimates that the $11-million Forté apartment building in Melbourne, Australia was built 30 percent faster because the materials were prefabricated.
  • 29. Applewood Pointe at Langton Lake Location: Roseville, Minnesota Architect: JSSH Architects Occupancy: 48 units The 48-unit four-story wood structure had a one-hour fire rating; it was sited over a three-hour rated pre-cast concrete parking garage, for a total of 123,964 square feet. According to Roger Johnson with JSSH Architects of Minnetonka, Minnesota, wood- frame was the most cost-competitive option, at $80 per square foot complete. Photo courtesy of Applewood Pointe Cost Benefits
  • 30. Emory Point Location: Atlanta, Georgia Structural Engineers: Ellinwood + Machado Consulting Structural Engineers Occupancy: 442 units Type of construction: One five-story wood-frame building over slab-on grade and three four-story wood-frame buildings over one-story concrete podiums A number of systems were considered, and wood was the most economical. For the structural frame portion only, the wood design cost approximately $14 per square foot compared to $22 per square foot for a 7-inch post- tensioned concrete slab and frame. The huge wood-frame project was completed in just over a year, which provided additional cost savings. Photo courtesy of Ellinwood + Machado Structural Engineers
  • 31. Fire Safety  Two design approaches to access structural passive fire protection measures 1. Encapsulation 2. Charring Research shows mass timber buildings behave very well in fire Photo: iStock (stock)
  • 32. Advances in building science and fire suppression systems have expanded the scope and role for wood structural and finish materials. CLT Fire Testing Results  American Wood Council test on a load-bearing five-ply CLT wall  Test specimen lasted 3 hours, five minutes & 57 seconds  Well beyond the two-hour goal Photo: FPInnovations
  • 33. Shake Table Test – Six Story Wood Building In 2009, a full size prototype of a six-story wood-frame building successfully passed a seismic ‘shake table’ test conducted in front of 400 international observers in Japan. Subjected to seismic forces greater than those of the 1995 Kobe earthquake, the structure suffered no visible damage. Photo courtesy of IVALSA
  • 34. Acoustics  The mass of the wall contributes to its acoustic performance  Additional acoustic benefits with sealants and other types of membranes to provide air tightness used by builders CLT Handbook, FPInnovations, 2011 Mass timber building systems provide appropriate noise control for both airborne and impact sound transmission. Photo courtesy of Karakusevic Carson Architects
  • 35. Building Height Considerations  Mass timber buildings have minimal shrinkage over time The 10-story Forté project used a conventional platform-based CLT system. Photo courtesy of Land Lease
  • 36. Code Approvals  U.S. and Canadian building codes do not explicitly recognize mass timber systems – this does not prohibit their use  2015 edition of the IBC will recognize CLT products when they are manufactured according to the new ANSI/APA standard  CLT walls and floors permitted in all types of combustible construction
  • 37. LifeCycle Tower ONE Location: Dornbirn, Australia Architect / Contractor / Developer: Cree GmbH Year of completion: 2012 When Cree GmbH developed their LifeCycle Tower system, they knew the best way to sell the concept was to prove its viability. Wood’s environmental and structural benefits were key considerations for LCT ONE. Photo courtesy of Cree Buildings, Inc.
  • 38. Responsible Revolution Tall wood buildings are not only possible, but the design and build concepts are being proven around the world. Photo courtesy of Cree Buildings, Inc. Photo courtesy of Karakusevic Carson Architects Rendering courtesy of mgb
  • 39. Photo by David Lena;courtesy of HMC Architects
  • 40. For more information on building with wood, visit rethinkwood.com THANK YOU!