1229-31 25th St. NW Washington D.C.
Charles Miller
Construction Management
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Note: While great efforts have been taken to provide accurate and complete information on the pages of CPEP, please be aware that the information contained herewith is considered a work-in-progress for this thesis project. Modifications and changes related to the original building designs and construction methodologies for this senior thesis project are solely the interpretation of Charles Miller. Changes and discrepancies in no way imply that the original design contained errors or was flawed. Differing assumptions, code references, requirements, and methodologies have been incorporated into this thesis project; therefore, investigation results may vary from the original design.

The header renderings were created by Shalom Baranes Associates and have graciously been supplied with permission to use for Charles Miller's Senior Thesis.


_West End 25 Statistics:

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Project Team

Vornado - Charles E. Smith (http://smithcommercialrealty.com)
General Contractor: 
James G. Davis Construction Cooporation (http://www.davisconstruction.com)
Shalom Baranes Associates Architects (http://www.sbaranes.com)
    Structural:  Tadjer Cohen Edelson Associates (http://www.tadjerco.com)
    MEP:   GHT Limited (http://www.ghtltd.com)                                
    Civil:       Bohler Engineering (http://www.bohlereng.com)                               
Interior Designer:  Forrestperkins (http://www.forrestperkins.com/index3.php)
Landscape:  Oculus (http://www.oculus-dc.com)

General Building Data

Building Name:   WestEnd25
Location of Site:  1229-1231 25th St. NW Washington D.C.
Building Occupant Name:  Multiple OccupantsOccupancy or function
Type of Building:  Residential
Size: 323,380 sq. ft.
Total Levels:  Below grade are two levels of parking.  Six stories of two separate existing office buildings have been combined to form a U shaped footprint facing east.  An additional four stories of common residency, a penthouse and a rooftop pool terrace were added to the existing structure. 
Dates of Construction: 3/1/07 – 12/24/09
Cost Information: $75,881,149 GMP
Project delivery method: Negotiated GMP
Zoning: Commercial Residential
Site Area: 44,324 sf
Historical requirements of building or zone: None that apply
Applicable Codes:
Building: International Code Council – IBC 2000 Edition as Amended by the DC Building Code Supplement 2003 (DCMR12A)
Mechanical: International Mechanical Code, 2000 Edition
Electrical: NFPA 70, National Electric Code, 1996 Edition
Plumbing: International Plumbing Code, 2000 Edition

Building Features

The architectural design of WestEnd25 developed from the existing building.  Two six story office buildings have been redesigned into a ten story luxury apartment building.  The footprint of WestEnd25 resembles a U shape facing the adjacent NW 25th Street.  The U shape provides the opportunity for a luxurious courtyard with a entrance colonnade, water fountain, and beautiful landscaping.  On the west facing facade a curtain wall provides views of the park across 25th Street.  Atop WestEnd25 are multiple terraces and green spaces for residences to enjoy.  Within WestEnd25 are 283 luxury apartments that include high end finishes for their residences.  The layout of the apartments is such that there are apartments on either side of a central corridor providing every apartment with an exterior view.

The alley wrap on the north, south and east façades is primarily a brick cavity wall with metal stud backing.  There are several punched openings for windows and terrace doors.   The courtyard facades and the penthouse facades are glass curtain walls. 
The roof includes many unique features including, a rooftop pool, paved terraces, and vegetation.  For the vegetated sections the roof consists of a waterproofing membrane, modified bituminous sheet air barrier, insulation, root barrier, filter fabric and a lightweight engineered soil to grow the vegetation.  The rest of the roof is a built up roofing system consisting of a fluid applied waterproofing membrane beneath high density styrofoam insulation with various toppings for this system including stone ballast, roof walk pavers and terrace pavers. 

Building Systems

Demolition workflow started at the north building, 1231 from 25th St. east to the alley.  Work then flowed to the south building 1229 in a similar fashion.  The connecting concrete slab is placed to connect the first six floors of building 1229 and 1231.  Concrete is placed with a Peiner SK 315 tower crane and bucket and the workflow starts with the connecting slabs and then resembles that of the demolition, starting at the west side of the 1231 building, following the building footprint to building 1229.  The crane is located at the center and the formwork is traditional timber formwork.  Access to the site will be from 25th street, which will have at least one lane of traffic open at all times.  All deliveries will enter on the south end of the site and exit the north end of the site.  The park wrap is a curtain wall is a panelized system that is installed from the interior of the building. A hydraulic mast climbing scaffold system will be used for the masonry façade.  The sidewalk adjacent to the site will be closed to pedestrians and the parking lane on the east side of 25th St NW will also be closed for the duration of construction.  Temporary pedestrian crosswalks have been established.  Furthermore, flag persons will be used to direct traffic when deliveries are expected and when there is heavy traffic during the mornings.  Material hoists will be located on the courtyard side of both the north and south buildings and will be the primary source of vertical transportation until elevators are installed. The general contractor was brought on board to develop preliminary budgets and to make sure the architects were designing within the owner’s budget.  The role of the general contractor evolved into a providing construction services with a negotiated GMP.

The power for WestEnd25 is being supplied by a main feed of 3 phase 2,500 Amp service which is received from the Potomac Electric Power Company, PEPCO, from 25th street.  There were two existing power vaults for each of the existing buildings.  The vault at building 1229 carries the 3 phase 460 voltage supply and the vault at building 1231 carries the 3 phase 208 voltage supply.   The switchgear rooms are located on the west side of the first level basement and distribute lines up to the first floor down the corridors to the risers on the east side of the building.  From the risers power is distributed to every apartment on each floor and each apartment is metered individually.  Each apartment contains a unit load center that monitors the amount of power used in that apartment. 

The lighting of WestEnd25 has been design to be aesthetically pleasing to the residents.   The lighting for the kitchens and living areas in the apartments are track lighting with 4 and 3 heads, respectively.  Other lighting inside the apartments includes ceiling recessed fluorescent fixtures for bedrooms, bathroom, and closets.  The general public areas are illuminated by architectural lighting fixtures, such as down light, wall washers, and LED cove strips.  The exterior courtyard and the roof terraces are also light by decorative fixtures which illuminated pedestrian pathways as well as accenting foliage.

The apartments of WestEnd25 are conditioned by water cooled heat pump units.  These units are self contained floor mounted horizontal packages with heating and cooling capabilities for each apartment.  This allows for multiple independent conditioned zones.   To complete the mechanical system there are four natural gas boilers to warm the condensing water during the peak heating periods and there is also a cooling tower to dissipate the heat energy from the condenser water during periods of high cooling demand.  Basic considerations for this type of system are the low installation cost and the independent conditioning flexibility.  Also, included in the public conditioning system are two enthalpy wheels that transfer heat from exhaust air and outdoor air depending on loads.  Therefore, outdoor air is pre-cooled or pre-heated with exhaust air form the conditioned zones.  

The garage of WestEnd25 is a conventionally reinforced concrete 2-way flat slab structure with drop panels over concrete columns with a spread footing foundation and a concrete slabs on grade.  The existing structure of WestEnd25 consists of conventionally reinforced two way concrete slabs with varies sections of waffle slabs.  The typical slab thickness of the existing structure is 7.5”.   The project’s additional four floors and six connection slabs are post-tensioned concrete.  The typical slab thickness of the connection slabs is also 7.5” but the typical thickness of the additional floors is 6”.  The column grid of 20’ by 20’ is maintained throughout WestEnd25.  The typical column sizes for building 1231 are 24” and 26” diameter columns in the garage and 18”x18” and 20”x20” existing columns that will maintained through the additional floors.  The typical column sizes for building 1229 are 24”x24” columns in the garage and 18”x18” and 20”x20” existing columns that will maintained through the additional floors.  The connecting structure will be supported with 18”x18” columns. 

Fire Protection: 
The primary system for the interior conditioned spaces of west end is a wet pipe system.  For non conditioned areas such as the garage and trash chute a dry pipe system is used for fire protection.  Sprinkler heads are encapsulated fusible alloy and spring lever actuated sprinklers.  The passive system involves a voice fire alarm system with elevator recall, stair pressurization, fireman’s phones, remote station notification and security system interface.  There is also a standby electric diesel generator for emergency power for the life safety equipment, including exit lighting fixtures, fire alarms, fire pump, pressurization system and smoke removal system.  

WestEnd25 uses Gen-2 Otis elevators.  These elevators are unique in that the mechanical system comes as a prepackaged unit that can be easily placed with a crane above the elevator shaft and installed within about half the duration of traditional elevators.  The Gen-2 uses a flat encased cable belt system to minimize space.  There are four primary elevators, two in building 1229 and two in building 1231.

There are two telecommunication closets on each floor and each ant next to the electrical closets.   Each room of WestEnd25 contains multiple data service locations for each apartment, one in the location for each bedroom and one in the living area.  The data service locations consist of telephone, internet connections and cable connections.

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This site was last edited by Charles Miller on 9/5/08 and is hosted by the AE Department © 2008