The Prado Condominiums
Topping out at 185 ft above street level, The Prado is the second tallest residential building
to be constructed in the Golden Triangle area of Denver, Colorado. This is one of three luxury
residential projects by the same developer that meet the demand for executive living in the
heart of South Denver. Each project has similar aesthetic characteristics that easily identify a
signature owner, and each utilizes concrete as the framing material of choice.
One of the developerís requests was to have open terraces for as many units as possible.
Achieving this required that virtually every floor have a different configuration. Concrete framing
allowed tremendous flexibility with cantilevers, thus permitting over 55% of the units to
have terraces. This was not only beneficial to the individual living space, but gave the building
a stepping effect that greatly reduces bulk and allows sunlight to reach the street level.
The 18 stories of The Prado house 3 levels of above grade parking, a ground floor retail space,
and 108 residential units. Complications from a high water table allowed only a single level of
parking below grade. The overall building dimensions are 180 ft by 140 ft at the base, and step
back to 130 ft by 80 ft at the roof.
Due to City of Denver zoning requirements that limit buildings to a height of 200 ft, approximately
150,000 sq ft of residential space had to be packed within 15 stories. This was accomplished
by utilizing a 9-in.-thick post-tensioned concrete flat plate on the residential floors.
A composite steel floor system was not used because it would have required more than twice
the floor depth than the post-tensioned slab to span the typical 28-ft by 27-ft-6 in. bays. Larger
floor-to-floor heights would have resulted in 2 fewer floors and 12,000 sq ft less saleable area.
A 10-in.-thick concrete flat plate with mild reinforcing is used on the parking floors. Typical
columns are 24 in. by 24 in. with reinforcement ratios ranging from 1% to 6%. Mechanical
couplers were used to splice the longitudinal bars for reinforcement ratios in the 4% to 6%
range. At the transfer level, 2-ft-wide by 4-ft-deep post-tensioned transfer girders support
7 floors from above.
Concrete shear walls are used as the lateral-force-resisting system. The wall thickness is
16 in. from the foundation to the 11th floor, and 12 in. from the 11th floor to the roof.
The columns are supported on 2-ft to 4-ft-diameter drilled piers that penetrate bedrock at
approximately 15 ft below grade. The shear walls are supported on 5-ft-6-in.-thick mats with
4-ft-diameter drilled piers.
A 5,000-psi concrete mix with Type I cement and 3/4-in. aggregate was specified for the slabs,
columns, and shear walls. A similar 4,000-psi mix was used for foundation walls and pier caps.
In addition to satisfying the requirements noted above, concrete framing provides superior
acoustic performance, which is very important for residential applications. The concrete walls
and slabs reduce sound transmission and provide an acoustic separation that far exceeds the
requirements of the building code. Also, significant savings were realized compared to the steel
alternative, since the lower floor-to-floor heights with concrete framing meant shorter vertical
runs for the facade, vertical transportation, and all other utilities. Furthermore, additional
fireproofing and finished ceilings were not needed with the concrete system.
The Prado adds to the district a neo-historic form that will continue to enrich this area for many
years to come.
Corporation, Denver, CO
Blue Sky Studio, P.C.,
Martin Design, Inc.,
The Weitz Company,
Associates, Denver, CO