EE152

Case Study: Esprit

This presentation is protected by U.S.

and international copyright laws.

Reproduction, distribution, display and

use of the presentation without written

permission of the speaker is prohibited.

This program is registered with AIA CES for continuing

professional education. As such, it does not include

content that may be deemed or construed to constitute

approval, sponsorship or endorsement by the AIA of any

method, product, service, enterprise or organization. The

statements expressed by speakers, panelists, and other

participants reflect their own views and do not necessarily

reflect the views or positions of The AIA or of AIA

components, or those of their respective officers,

directors, members, employees, or other organizations,

groups or individuals associated with them. Questions

related to specific products, publications, and services

may be addressed at the conclusion of this presentation.

Learning Objectives 1. Discover why wood was the ideal structural material for the

Esprit project and others like it to achieve high-density mid-rise buildings.

2. Review the building code requirements for designing five-story and higher wood-framed multifamily projects.

3. Explore the construction challenges of building five stories and higher with wood framing.

4. Discuss the height and area limitations of designing five-story wood-frame multifamily buildings.

Esprit Marina del Ray, CA

Lisa Podesto, MS, PE

Senior Technical Director, WoodWorks

Esprit Luxury Apartments

Location: Marina del Rey, CA

Architect:

Togawa Smith Martin, Inc.

Engineer:

Group M Engineers

Size: 5 buildings – 482 units

Completed: 2007 – Phase One

Esprit is a luxury apartment development on two parcels of land in Marina del Rey, California. It’s unique in that it accommodates both apartment dwellers and boaters. Boat slips surround the project and the units are creatively configured to include a mix of apartment types, from flats to multi-level townhouses, and to provide views for all units.

Phase One of Esprit includes five buildings and 482 units. Phase Two will include an additional 640 units for a total of 1,022. The buildings in the background include four stories of Type V wood construction over a Type I concrete podium. The buildings in the foreground include five stories of Type III wood construction over a Type I podium. Phase One was designed under the previous building code which allowed a maximum height of 65 feet for wood-frame construction. The current version of the code allows taller wood buildings … and the architect of this project, Tim Smith, says he’ll take advantage of the new provisions to go higher with Phase Two.

Esprit

4-story buildings

5-story buildings

Every unit has a view

Wood buildings: How high can we go?

Most midrise wood buildings are Type V Construction and four stories or less. However, Type III offers far greater opportunities for achieving high density at a relatively low cost ... while of course meeting all requirements for safety and performance. Like all construction types, Type III has base limitations with regard to height, number of stories and square footage. However, the IBC allows increases to these tabular amounts per other code sections.

Base Code Height

1989 – UBC Base code height – Table 5B

Type IIIA / 2009 – IBC Base code height – Table 503

For example, when a building has an NFPA 13-compliant automatic sprinkler system, the floor area can be increased by 300% for a one-story building and 200% for a multi-story building. In addition to the area increase, IBC Section 504.2 allows a 20-foot increase to the tabular building height and an additional story above the grade plane. The exception to his is Group I-2 occupancies, which include hospitals and nursing homes and are not allowed the extra story. Adding an automatic sprinkler system not only means that a five-story wood building is allowed, it means a maximum height of 85 feet instead of 65 feet. So how do we maximize the vertical envelope to take advantage of the extra height when a typical five-story building is only about 55 feet?

1989 – UBC Sprinkler increase – Section 506

Type IIIA / 2009 – IBC Sprinkler increase – Section 504

Add 1 floor Increase height 20 feet

Sprinkler System

First we add another level. Under the 2009 IBC, you can add a wood-frame mezzanine on top of a multi-story wood building. The area of the mezzanine can’t be more than 1/3 of the floor below and isn’t defined as a ‘floor’ or ‘story.’ Starting with the base height and then adding a sprinkler system and now a mezzanine gets us to six levels of wood-frame construction and about 65 feet in height.

1989 – UBC 1989 – UBC

Mezzanine – Section 507

Type IIIA / 2009 – IBC Mezzanine – Section 505

Add level 1/3 of floor below & not defined as a floor

Mezzanine

A Type I podium increases the height of the building even further. The wood-frame and concrete portions of a podium building are designed as two separate structures with a 3-hour fire separation between them. A podium designed for retail is typically about 15’ high. So, adding our sprinkler system, mezzanine and now a podium takes us to seven above-ground levels and about 70 to 75 feet in height. And how do we get to 85 feet?

1989 – UBC Podium – Section 311.2.2.1

2009 – IBC Type IIIA / 2009 – IBC

Type I Podium – Section 509.2 Separate buildings for area and stories

3-hour separation between Type I and III

Podium

… We use a sloping site to our advantage. The IBC recognizes that the world isn’t flat. It allows semi-basements or daylight basements providing they don’t extend from grade more than 12 feet at any one point and don’t extend more than 6 feet from the average grade. As with mezzanines, this ‘basement’ level is not considered a ‘floor’ or ‘story’ … but it gives us an eight-level building that’s in the range of 85 feet high. Using a combination of Type III and Type I, we’ve now maximized the vertical envelope.

Semi-Basement

1989 – UBC Height definition – Section 208

Type IIIA / 2009 – IBC Grade plane definition – Section 502

Add another level with daylight basement

Esprit was designed under the previous code, which had a maximum height of 65 feet measured from the high side of the site and 75 feet from the low side of the site. Still, the Type III buildings took advantage of automatic sprinklers to achieve five stories, a podium for parking, and a daylight basement for parking. Phase Two will also include a mezzanine.

Esprit

Density Summary

Units/Acre

5-story wrap & 4-story podium 60-80

5-story with subterranean 100-120

parking

5-story with retail podium 100-120

5-story with residential podium 120-140

5-story with mezzanine + 125-145

residential podium Zoning dictates density limits, and these are the average densities for different types of 5-story wood buildings. The bottom line: by taking advantage of Type III construction and the different code provisions, we can achieve densities in the range of 145 units per acre. Tim says his firm, Togawa Smith Martin, has reached 165 units per acre with a wood-frame building. When you get to this level of density, you’re competing with Type I structures that are 10 and 11 stories … and you’re doing it for about a third less the cost. Tim says that a typical Type III building over a podium costs about $200/square foot, while a Type I building costs $275-$300/square foot.

Do Type III wood buildings have special fire protection requirements?

• Exterior bearing walls – 1-hour

• Fire walls – 2-hour

• Exterior walls – FRT lumber

• Exterior bearing walls – 2-hour

• Fire walls – 3-hour

Type V-A Type III-A

In many ways, Type V and Type III wood buildings have similar requirements. The key differences are: • In Type III buildings, exterior walls must be of non-combustible materials so fire-retardant-treated wood must be used. In a Type V building, exterior walls can be of any material permitted by the IBC. • Exterior bearing walls are 2-hour-rated in Type III buildings instead of 1-hour. • And fire walls have to be 3-hour rated instead of 2-hours. Although these differences can increase construction costs somewhere between 8 and 15 percent, Type III is still highly cost effective when compared to Type I buildings.

Here’s an example detail showing 2-hour exterior walls. Note that an additional layer of drywall is needed on either side to achieve that rating. The important thing to note is that only bearing walls have to be 2-hour rated, not all of the walls in a Type III building.

As a result, it’s useful to minimize bearing walls on the exterior of the building in order to keep construction costs down. One way to do this is to keep the framing parallel to the exterior wall, which means the majority of exterior walls are non-bearing. This is a technique Tim used with Esprit and he says it makes the construction costs of a Type III building comparable to Type V.

• Frame to demising walls rather than

exterior walls.

• At last exterior walls frame to

beams/columns.

Other Alternatives

This photo shows two examples of damp-proofing.

Damp-proofing

What are some other design considerations for Type III buildings?

A B C

Zone of Movement

Traditional platform framing used in low-rise construction can also be used in mid-rise projects, but special attention has to be paid to the floor-to-wall detail in order to minimize cumulative building shrinkage, which becomes more of an issue the more floors you have. The other options is to use semi-balloon framing which is popular with Type III mid-rise because it also addresses FRT and 2-hr rating continuity at the exterior wall. Esprit used semi-balloon framing.

With taller wood buildings, you also have to address seismic and wind forces. As with this building, Esprit included exterior plywood shear walls.

Exterior Plywood Shear Walls

Continuous tie rods and compression studs are typically used at the ends of the shear panels, which can pose a challenge with regard to mechanical and electrical systems.

Rods and Compression Studs

One answer is to separate the plumbing walls from the shear walls, as shown here, so there’s no conflict.

Separate Shear and Plumbing Walls

Size and spacing of studs also need to be considered. To hold the weight of the structure, lower floors require closer spacing and/or bigger studs. Usually only the top two floors use 2x4s at 16 inches on center.

Stud Size and Spacing

Water proofing is also essential. Wood buildings will last as long as you want them to providing you keep them water tight. Taller buildings require more sophisticated water proofing systems than a one- or two-story house.

Waterproofing

Is cost the main impetus for taller wood buildings?

• Versatility

• Workability

• Experienced trades

• Speed

• Adaptability

• Environmental Performance

Benefits of Wood

Americana at Brand Glendale, California

Architect: Togawa Smith Martin, Inc. Photo: Michelle Kam-Biron

Wood has a variety of advantages that make it ideal for mid-rise buildings. The building shown was designed by the same architect as Esprit and is part of the Americana at Brand complex in Glendale. It includes 238 apartments, 100 luxury condominiums, 75 upscale shops, and a 2-acre central park.

• Renewable

• Sustainable

• Embodied energy

• Energy-efficient

• Light carbon

footprint

Environmental Benefits

Although cost is often cited as the main reason to use wood, its environmental benefits—and its light carbon footprint in particular—have been cited around the world as a driving force behind taller wood buildings.

In North America, five- and even six-story wood buildings are becoming common. This is the first phase of Library Square, one of the first buildings to take advantage of a code change in British Columbia that increased the maximum number of stories in residential buildings from four to six.

Evolution Upward

Library Square 6 stories Phase 1 completed 2010 British Columbia JM Architects Photo: naturallywood.com

And these are the carbon benefits for Library Square. The volume of wood in the building was entered into a free carbon calculator that’s available at woodworks.org. The calculator then estimated the how much carbon is stored in that volume of wood … the greenhouse gas emissions avoided by using wood instead of steel or concrete … and how long it takes North American forests to grow that volume of wood. It also used the EPA’s Greenhouse Gas Equivalencies Calculator to translate those figures into relatable units. Source: Estimated by the Wood Carbon Calculator for Buildings, based on research by Sathre, R. and J. O’Connor, 2010, A Synthesis of Research on Wood Products and Greenhouse Gas Impacts, FPInnovations CO2 refers to CO2 equivalent.

Carbon Benefits

Elsewhere in the world, building codes have allowed even taller wood buildings. This 10-story building in Australia is made from cross laminated timber (CLT) and is currently the world’s tallest all-wood apartment building. In the U.S., the International Code Council recently approved changes that will see CLT recognized in the 2015 IBC.

Evolution Upward

Forté 10 stories Australia Developer and photo: Lend Lease

A report from Canadian architect Michael Green of MGA and J. Eric Karsh from Equilibrium Consulting Inc.—The Case for Tall Wood Buildings: How Mass Timber Offers a Safe, Economical, and Environmentally Friendly Alternative for Tall Building Structures—outlines a compelling case for building even taller wood buildings. It shows that mid-rise buildings (6-12 stories) and tall buildings (up to 30 stories) can be safely, efficiently, and economically built using mass timber construction techniques.

Evolution Upward

The Case for Tall Wood Buildings Michael Green AIBC FRAIC AIA

Eric Karsh MEng, PEng, StructEng, MIStructE, Ing.

Canadian Solution

A report from Canadian architect Michael Green of MGA and J. Eric Karsh from Equilibrium Consulting Inc.—The Case for Tall Wood Buildings: How Mass Timber Offers a Safe, Economical, and Environmentally Friendly Alternative for Tall Building Structures—outlines a compelling case for building even taller wood buildings. It shows that mid-rise buildings (6-12 stories) and tall buildings (up to 30 stories) can be safely, efficiently, and economically built using mass timber construction techniques.

Evolution Upward

Life Cycle Tower CREE by Rhomberg Austrian Concept Local Solution

A report from Canadian architect Michael Green of MGA and J. Eric Karsh from Equilibrium Consulting Inc.—The Case for Tall Wood Buildings: How Mass Timber Offers a Safe, Economical, and Environmentally Friendly Alternative for Tall Building Structures—outlines a compelling case for building even taller wood buildings. It shows that mid-rise buildings (6-12 stories) and tall buildings (up to 30 stories) can be safely, efficiently, and economically built using mass timber construction techniques.

Evolution Upward

40 Story Wood Office Tower CEI Architecture NAOIP Office Building of the Future Design Competition

A report from Canadian architect Michael Green of MGA and J. Eric Karsh from Equilibrium Consulting Inc.—The Case for Tall Wood Buildings: How Mass Timber Offers a Safe, Economical, and Environmentally Friendly Alternative for Tall Building Structures—outlines a compelling case for building even taller wood buildings. It shows that mid-rise buildings (6-12 stories) and tall buildings (up to 30 stories) can be safely, efficiently, and economically built using mass timber construction techniques.

Evolution Upward

Timber Tower Skidmore, Owings and Merrill May 2013 US Solution

Contact Information

Lisa Podesto, MS, PE

Senior Technical Director

WoodWorks

lisa@woodworks.org

(503) 520-7966