The Outside/Structured Parking space type refers to an above-grade, ramp access, open-air structure specifically designed to accommodate vehicle parking. As defined for the WBDG, the Level of Service (LOS) (refer to Architectural Graphic Standards, 10th Edition, page 106) of the Inside/Basement Parking is LOS B, indicating use by some unfamiliar users, moderate daily turnover, and medium percentage of small cars and light trucks; and requiring one-way aisles of 11'-0" straight-ways and 13'-6" turns. See also WBDG Parking Facilities.
This parking garage has a high level of finish and architectural detail to complement the building it serves.
Photo credit: Ridgemont Construction
All parking structures—whether basement, structured, or surface—must provide for the safe and efficient passage of automobiles as well as visitors to and from their vehicles. Therefore, attention should be given to providing the maximum driver visibility possible at all turning points along the roadway as well as designing stairways and lobbies to offer maximum visibility from the outside for security of the visitors. As a sole use structure with no interior fit-out, typical features of outside structured parking include the list of applicable design objectives elements as outlined below. For a complete list and definitions of the design objectives within the context of whole building design, click on the titles below.
- Parking Spaces and Entrances: Accessible parking spaces must be provided for each parking structure associated with the building and calculated separately. At least one of every 6 accessible spaces, or fraction of 6, in each parking facility must be sized to accommodate vans. Accessible spaces must be dispersed among accessible entrances and be located on the shortest route to the entrances that they serve. (There are variations to the rules depending on the building type. See the U.S. Access Board for more information.)
- Finishes: Incorporate slip-resistant finishes to meet accessibility requirements.
- Signage: The international symbol of accessibility must be placed in front of the parking spaces mounted at least five feet above the ground, measured to the bottom of the sign. Van accessible spaces include the designation "van accessible".
Image credit: U.S. Access Board
- Visual Impact: The parking structure should not dominate the building site, but should complement it or be its own unique architectural expression. Through a combination of planning, architectural, and landscaping elements, the visual impact on the surrounding streets and developments can be minimized or enhanced. For example, structured parking is generally located to the rear or side of the building and away from the street or street intersections, while providing direct pedestrian access to the buildings. However, parking garages are becoming multi-use buildings with shops and restaurants along street fronts, and may also serve as a hub for different modes of transportation. So the aesthetics of the design should support the garage's ability to support different uses over time.
- Materials and Colors: Parking is as much of a destination as the building. Drivers are trying to locate the parking garage and the best way to enter it. Aesthetics play an important role in how the overall building and the companies/organizations within it are perceived. Care and attention should be given to the colors and materials used in the space to create a feeling of safety and ease of access. Durable materials and finishes should be used to maintain the appearance of the space.
- Graphics: Incorporate visually interesting and informative graphics to relay messages about directions, activities, and events within the building or surrounding area that the garage serves.
CDIA Daily Parking garage in Charlotte, North Carolina. Perforated panels are backlit to match the airport's blue color, reveal the truss structure, and provide visibility and ventilation to meet airport safety requirements. The white concrete columns provide contrast, while the point loaded, glass enclosed stair towers glow to create lanterns using dynamic blue LED signal lights.
Photo Credit: The Wilson Group
- Life Cycle Analysis: Incorporate materials, products, and systems that meet long-term life-cycle performance goals to reduce operations and maintenance costs.
- Maintenance: Care and maintenance of the parking structure should be part of the plan to keep the aesthetic value and prolong its service life.
- Plan for Additional Uses: Design parking for future adaptations into spaces such as shops, offices, or apartments, which will generate additional revenues. Consider renting out unused parking spaces to nearby tenants to share costs and also generate additional revenue. Consider developing near mass transit if building a new structure or even renovating an existing structure to save costs and promote alternative forms of transportation.
- Site Improvements: Typical site improvements directly related to the structured parking structure include ground cover, planting, irrigation systems—for example, sprinkler misters at integral planters on building spandrel panels, storm water drainage systems, vehicle entrance roadways, sidewalks, lighting, signage, fences, screens, buffer zones, roadway extensions to public streets, and connections to public utilities.
- Structural Requirements: The structure includes foundation, beams, columns, and slabs. The structural bay spacing and floor-to-floor heights are designed to accommodate vehicle circulation and parking. The standard substructure foundation includes reinforced concrete spread footing, water-resistant membrane with rigid insulation and with sealant sloped at footing, and gravel drainage course with filter mat over 4" drainage tiles. The slab on grade is typically 6", 4000 PSI, poured on top of a gravel base on compacted fill with a moisture barrier in between the gravel base and the slab. The slab is reinforced with welded wire fabric; and the joints and wall junctures are sealed with sealant. The structural frame, designed for a live load of 50 LB/SF, is typically precast, reinforced concrete structural columns and beams, and double "T" deck with concrete topping, allowing for a clear height under the "T" of 8'-6".
- Space Allocation: An average garage requires three to six times more square feet than the actual dimension of a car to accommodate drive aisles, ramps, and standard parking space dimensions. Land costs continue to rise, while the availability of space is becoming scarce. Consider incorporating lift technology or automated parking systems where land and space are at a premium. This can reduce the amount of needed square feet as well as save on construction costs and overall operating costs.
- Signage and Wayfinding: Signage should indicate all major internal pedestrian access points as well as external major roads and buildings. In structured parking, pavement markings are reflective paint and traffic control signage is usually reflective metal signs with minimum 5" high letters. The Manual on Uniform Traffic Control Devices for Streets and Highways (ANSI D 6.1e) provides guidance on pavement marking and signage.
- Parking Management: Curb-mounted parking booths with transaction windows and deal trays are installed at vehicular entrances/exits to manage entering and exiting vehicles. A cooling system, like a packaged terminal air conditioner (PTAC), is usually incorporated to supply the booth with outside air at a positive pressure relative to surrounding parking areas. Additionally, consider implementing electronic entry and exit machines, making it easier for users to self-park and pay. This is an excellent way to track garage traffic user patterns and manage money more effectively and safely.
Precast parking solutions offer speed of construction with significant time savings, less impact to construction sites, and flexible integrated architectural cladding options. Additionally, long-span structural precast systems mean fewer interior support columns are necessary, which give users increased visibility and a safer experience.
- Security Protection: Beyond parking management, several security measures are incorporated into typical structured parking structures to ensure the security of visitors. These generally include: uniform lighting coverage, preferably with energy-efficient light fixtures, closed circuit television (CCTV) cameras, card reader access control for vehicle entrance doors, concrete filled protective bollards to protect vehicle entry keypads and ticketing systems, and hydraulic lift wedge type barriers for egress control. Also critical are the exterior security systems, including CCTV cameras and building security flood lighting, related to the protection of elevator lobby space, stairs, and other support spaces accessible from the parking area. Depending on the level of protection desired, consider ballistic glazing for the parking booths. See also WBDG Secure / Safe—Security for Building Occupants and Assets.
- Fire and Life Safety: The structured parking structure is typically sprinklered for 1 hr. structure, 1 hr. exterior bearing walls, 1 hr. interior bearing walls, 1 hr. exterior non-bearing walls, 1 hr. floor construction, and 1 hr. roof construction. Proper notification systems, lighting, and signage are required to facilitate safe and speedy evacuations during an emergency. This is usually accomplished with proper fire alarm wiring, pull stations, strobes, annunciators, and exit signage. See also WBDG Secure / Safe—Fire Protection.
- Ice Prevention: Radiant heaters or slab heating coils are incorporated into the structured parking structure to prevent ice build-up, which could cause dangerous driving/walking conditions within the parking structure.
- Ventilation: Forced ventilation systems are installed in enclosed spaces.
- Drainage and Storm Water Management: Water runoff from vehicles is typically dealt with in structured parking structures by installing trench drains with cast iron covers at all vehicle entrance/exit points, sand and oil traps at all storm drain discharge points, and floor area drains at every low point. See also WBDG Low Impact Development Technologies.
- Lighting: Incorporate energy efficient lighting and lighting controls into the parking areas, entrances, and exits to improve lighting levels while also reducing energy use.
- Parking Priorities: Plan for and provide priority parking for hybrid cars and electric vehicles (EV). Also provide EV charging stations to contribute to the adoption of EVs. Many cities are requiring buildings with parking to be EV ready, meaning that wiring and conduits are built into the structure, even if charging stations are not.
- Construction Materials: Use durable and sustainable materials with a reduced carbon footprint or that are locally procured and/or recyclable. Consider the material life cycle in the decision-making process in order to reduce the production and consumption of new materials.
- Indoor Environmental Quality: Use natural ventilation, heat recovery, and other sustainable technologies whenever possible in any enclosed space within the garage.
- Photovoltaics: Incorporate solar panels whenever possible on the garage to support energy loads.
- Rooftop gardens and green space: The roofs of parking structures collect a lot of water. Capture the water and send it to a green roof, bio-swales, rooftop garden, or other green spaces around it. (See also Extensive Vegetative Roofs)
Duke's Research Drive garage incorporated a solar panel system that sits atop the seven-story parking garage. It provides 1.3 million kilowatt hours of electricity annually. It also covers the needs of the garage, putting excess energy back into the grid to power other buildings, and it reduces 430 metric tons of carbon from Duke's footprint, equivalent to 92 passenger cars being taken off the road. The LEED-certified deck, which holds around 1,900 cars, was built with sustainability in mind years before the solar panels were added. Efficient LED lights are used and rainwater is captured and reused for irrigation.
Photo courtesy of Duke University.
The following diagrams are representative of typical tenant plans.
Example Construction Criteria
For GSA, the unit costs for outside, structured parking are based on the construction quality and design features in the following table . This information is based on GSA's benchmark interpretation and could be different for other owners.
Relevant Codes and Standards
The following agencies and organizations have developed codes and standards affecting the design of structured parking. Note that the closed and standards are minimum requirements. Architects, engineers, and consultants should consider exceeding the applicable requirements whenever possible:
Community Services, Educational Facilities, Federal Courthouse, Health Care Facilities, Libraries, Office Building, Parking Facilities, Research Facilities
Basement Parking, Surface Parking
Accessible, Aesthetics, Cost Effective, Functional / Operational—Account for Functional Needs, Secure / Safe—Fire Protection, Secure / Safe—Security for Building Occupants and Assets, Sustainable—Enhance Indoor Environmental Quality (IEQ)
- Architectural Graphic Standards, 12th Edition by The American Institute of Architects, Dennis J. Hall. New York, NY: John Wiley & Sons, Inc., 2016.
- Green Roofs for Stormwater Runoff Control EPA/600/R-09/026 by the U.S. EPA. Cincinnati, Ohio: EPA, February 2009.
- Guide to FEMP-Designated Parking Structure Lighting by the Federal Energy Management Program. Washington, DC: FEMP, March 2013.
- High-Efficiency Parking Lighting in Federal Facilities Case Study of Camp Pendleton by the U.S. Department of Energy.
- Low Energy Parking Structure Design by the National Renewable Energy Laboratory (NREL). Golden, Colorado: NREL, January 2013.
- Planning and Design Guidelines, Chapter 05—Parking and Loading by City of Surprise, AZ.