The Advantages of Using Precast for Parking Structures
The Price Is Right
The economic advantages of using precast concrete for parking structures are readily apparent. By utilizing a "pretopped" double tee deck, the final driving surface is already in place—eliminating the need for expensive field-applied concrete toppings. In addition to the immediate financial benefits offered, the durability of the structure, established during the design phase, can offer long-term economy in the form of low maintenance and long life span. Because precast concrete is produced in a controlled environment, the end result is high performance at a relatively low cost. Given proper nominal maintenance, this translates into infrequent repairs and low operating costs for the owner. It's easy to see that precast's combination of efficiency and durability provides an economical one-two punch that is hard to beat.
Everything Under the Sun
Exterior finishes for precast/prestressed concrete parking decks range from form-finished gray concrete to painting or sandblasting. Countless concrete colors and numerous combinations of aggregates are available for an architectural finish. The possibilities are limitless.
It's Tough Enough
Extensive laboratory testing has proven that standard precast/prestressed concrete from a PCI-certified plant is far more durable than standard cast-in-place concrete. What's more, this improved durability is accomplished without additional corrosion protection. The heat-cured, high-performance concrete owes its superior durability to low water-cement ratio, air entrainment and cement content. Pretopped double tees have been the Mid-Atlantic standard for more than 25 years.
With a proven record of performance, precast concrete is the intelligent choice. No other building material offers its economy, durability and versatility. Why? Because corrosion research from a two-year study confirms that the low water-cement ratio and curing methods used by precasters nationwide result in low permeability and high resistivity to chlorides. Time is on your side.
MAPA Standards
Concrete:
- < 0.40 water/cement ratio
- 6,000psi concrete in floor members
- 5,000 psi concrete in other products
- 6" of cover over the primary reinforcement from the deck surface on floor members
- PCI-certified quality assurance
 Connections:
- Use galvanized connections where exposed to view
- Use stainless steel tee-to-tee connections where exposed to view
- Use expansion joints on structures with length in excess of 300'0"
- Grind joints prior to sealing
- Seal with a high-quality material and applicator; MAPA recommends 5 years of experience
- Use waterproofing sealant in connection pockets
- Eliminate architectural caulking, wherever possible
- Specify PCI MNL 116 tolerances
- Use care in specifying welded connections or those that provide excessive restraint
Design:
- Provide positive drainage—use minimal cast-in-place topping
- Use pretopped double tees with a 4" flange
- Extend exterior precast concrete beams 3'6" above the deck to avoid the use of metal rails
- Use shear walls or moment frames for lateral load resistance
- Use 30'0" bay sizes (or greater) consistently throughout the structure—wherever possible
- Where architectural concrete is desired, integrate it with the structural members
- Use two-way traffic with 90 parking
- Use walls as vertical elements to support ramped areas
- Use precast concrete stairs and stairwalls, wherever possible
- Use typical 10'0" floor-to-floor heights
- Utilize a minimum double tee depth of 26" with a 4" flange
- Where architectural finishes are desired, use PCI MNL 117 as a finish reference only; tolerances should be as noted in PCI MNL 116
 Specifications:
- GUIDE SPECIFICATION for precast/prestressed concrete parking structures
- When cast-in-place areas are unavoidable, be sure that sealers are used to protect them
- When cast-in-place areas are unavoidable, be sure that the reinforcing steel is epoxy-coated
- Institute annual inspections and maintenance procedures in accordance with the Precast/Prestressed Concrete Institute and the National Parking Association
- Specify PCI Plant Certification (no independent testing required)
- Specify that engineering and erection of the precast concrete products are the Precaster's responsibility
- Specify the use of an AIA A401 subcontract
- Specify proven, experienced waterproofing systems and applicators with a minimum warranty requirement
- More and more owners and agencies are selecting precast concrete as their material of choice for parking structures. Here's why.
Safety First
The spacious areas created by open parking structures improve and simplify security measures. With fewer columns than other structural systems, the precast concrete system provides greater line-of-sight, with fewer areas in which criminals can hide. Vertical wall elements can be minimized within the structure, and stair or elevator towers can be designed in an open fashion that offers the utmost in passive security. Effective lighting is easily obtained, and video surveillance (where required) is practical.
 Time Is On Your Side
Structural design of the precast concrete components begins before the builder has finished awarding other trade packages. With the precast concrete specialty engineer leading the way, the design process flows smoothly. Site preparation and foundations proceed while the precast concrete components are being manufactured in a PCI-certified plant. Early products are shipped while other precast concrete members are still being produced. Daily, thousands of square feet of deck area are erected by each crane so that a moderately-sized structure can be erected in a matter of weeks. The owner occupies the structure earlier—paying less interest on his construction loans, generating a faster revenue stream and minimizing business disruption.
Ready When You Are
Precast concrete garage components are readily available from a number of MAPA producers. Each producer has the qualifications and reliability to generate products which meet the needs of the owner, designer and construction professional. MAPA is proud that many of its members are precast industry pioneers.
The Long Run
Corrosion of a parking garage's structural reinforcement can be costly to repair and life threatening. Precast parking structures, through design and manufacturing, provide the ultimate in corrosion control, eliminating unnecessary, costly repairs. A national survey of 230 structures concluded that pretopped systems perform best—without corrosion from chlorides or the need for surface sealing. Every parking garage, regardless of its structural system, will require preventative maintenance in some form to extend its useful life. But you can help prevent corrosion with precast concrete.
Architectural Precast | Hollowcore | Parking Structures | Sports Facilities
Wall Panels | Total Building Systems | Drawing Details
|
