Fifteen Twenty-One Second Avenue

Seattle
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    Metrics
Height 134.1 m / 440 ft
Floors 38
Official Name
The current legal building name.

Fifteen Twenty-One Second Avenue

Type
CTBUH collects data on two major types of tall structures: 'Buildings' and 'Telecommunications / Observation Towers.' A 'Building' is a structure where at least 50% of the height is occupied by usable floor area. A 'Telecommunications / Observation Tower' is a structure where less than 50% of the structure's height is occupied by usable floor area. Only 'Buildings' are eligible for the CTBUH 'Tallest Buildings' lists.

Building

Status
Completed
Architecturally Topped Out
Structurally Topped Out
Under Construction
Proposed
On Hold
Never Completed
Vision
Competition Entry
Canceled
Proposed Renovation
Under Renovation
Renovated
Under Demolition
Demolished

Completed

Completion

2008

Country
The CTBUH follows the United Nations's definition of Country, and thus uses the lists and codes established by that organization.

United States

City
The CTBUH follows the United Nations's definition of City, and thus uses the lists and codes established by that organization.

Seattle

Address

1521 Second Avenue

Function
A single-function tall building is defined as one where 85% or more of its usable floor area is dedicated to a single usage. Thus a building with 90% office floor area would be said to be an "office" building, irrespective of other minor functions it may also contain.

A mixed-use tall building contains two or more functions (or uses), where each of the functions occupy a significant proportion of the tower's total space. Support areas such as car parks and mechanical plant space do not constitute mixed-use functions. Functions are denoted on CTBUH "Tallest Building" lists in descending order, e.g., "hotel/office" indicates hotel function above office function.

Residential

Structural Material
All-Steel
Both the main vertical/lateral structural elements and the floor spanning systems are constructed from steel. Note that a building of steel construction with a floor system of concrete planks or concrete slab on top of steel beams is still considered an “all-steel” structure as the concrete elements are not acting as the primary structure.

All-Concrete
Both the main vertical/lateral structural elements and the floor spanning systems are constructed from concrete which has been cast in place and utilizes steel reinforcement bars and/or steel reinforced concrete which has been precast as individual components and assembled together on-site.

All-Timber
Both the main vertical/lateral structural elements and the floor spanning systems are constructed from timber. An all-timber structure may include the use of localized non-timber connections between timber elements. Note that a building of timber construction with a floor system of concrete planks or concrete slab on top of timber beams is still considered an “all-timber” structure as the concrete elements are not acting as the primary structure.

Mixed-Structure
Utilizes distinct systems (e.g. all-steel, all-concrete, all-timber), one on top of the other. For example, a Steel Over Concrete indicates an all-steel structural system located on top of an all-concrete structural system, with the opposite true of Concrete Over Steel.

Composite
A combination of materials (e.g. steel, concrete, timber) are used together in the main structural elements. Examples include buildings which utilize: steel columns with a floor system of reinforced concrete beams; a steel frame system with a concrete core; concrete-encased steel columns; concrete-filled steel tubes; etc. Where known, the CTBUH database breaks out the materials used within a composite building’s primary structural elements.

All-Concrete

Height
Architectural
Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the architectural top of the building, including spires, but not including antennae, signage, flag poles or other functional-technical equipment. This measurement is the most widely utilized and is employed to define the Council on Tall Buildings and Urban Habitat (CTBUH) rankings of the "World's Tallest Buildings."

134.1 m / 440 ft

To Tip
Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the highest point of the building, irrespective of material or function of the highest element (i.e., including antennae, flagpoles, signage and other functional-technical equipment).
134.1 m / 440 ft
Floors Above Ground
The number of floors above ground should include the ground floor level and be the number of main floors above ground, including any significant mezzanine floors and major mechanical plant floors. Mechanical mezzanines should not be included if they have a significantly smaller floor area than the major floors below. Similarly, mechanical penthouses or plant rooms protruding above the general roof area should not be counted. Note: CTBUH floor counts may differ from published accounts, as it is common in some regions of the world for certain floor levels not to be included (e.g., the level 4, 14, 24, etc. in Hong Kong).

38

# of Apartments
Number of Apartments refers to the total number of residential units (including both rental units and condominiums) contained within a particular building.

143

Tower GFA
Tower GFA refers to the total gross floor area within the tower footprint, not including adjoining podiums, connected buildings or other towers within the development.

48,820 m² / 525,494 ft²

Rankings

  • By Location
#
9158
Tallest in the World
#
35
Tallest in Seattle

Construction Schedule

2007

Construction Start

2008

Completed

Architect
Architect of Record

Usually takes on the balance of the architectural effort not executed by the "Design Architect," typically responsible for the construction documents, conforming to local codes, etc. May often be referred to as "Executive," "Associate," or "Local" Architect, however, for consistency CTBUH uses the term "Architect of Record" exclusively.
Opus International Consultants
Structural Engineer
(not specified)
Opus International Consultants
Developer
Opus Group
Architect
Design

Usually involved in the front end design, with a "typical" condition being that of a leadership role through either Schematic Design or Design Development, and then a monitoring role through the CD and CA phases.
Weber Thompson
Architect of Record

Usually takes on the balance of the architectural effort not executed by the "Design Architect," typically responsible for the construction documents, conforming to local codes, etc. May often be referred to as "Executive," "Associate," or "Local" Architect, however, for consistency CTBUH uses the term "Architect of Record" exclusively.
Opus International Consultants
Structural Engineer
(not specified)
Opus International Consultants
Contractor
Main Contractor

The main contractor is the supervisory contractor of all construction work on a project, management of sub-contractors and vendors, etc. May be referred to as "Construction Manager," however, for consistency CTBUH uses the term "Main Contractor" exclusively.
Opus Group