Getting the Most Out of Your Dollar
By David Marshall
In this tough economy, parking garage owners and operators must be mindful of their bottom line. This is most crucial during the planning and design of a new garage. Here’s a look at some design considerations and durability and maintenance options that can stretch your dollar.
Design Decisions During the initial planning and design, many factors have an impact on the cost of the project. Owners should closely review each of these options to ensure that they are truly getting the most “bang for their buck.”
Functional Design: An efficient garage layout is the most important factor affecting the construction cost of a new parking structure. Efficiency, often measured in gross square feet per stall, represents how much structure an owner will build for a given parking demand. Owners should look for a functional design layout that provides 300 to 340 gross square feet per stall, depending on the structural system selected.
Efficiency of a parking garage is established during the functional design phase of a project. Engaging an experienced parking design professional to perform this will optimize the efficiency of the garage, and thus minimize its initial costs.
Functional design tasks include:
• Locating the garage on the site.
• Developing garage geometry, including number of floors and bays, column grid, vehicle ramp layout and floor-to-floor dimensions.
• Developing parking stall layout.
• Vehicle circulation, such as establishing drive lanes and vehicular entrance/exit lanes.
Aesthetic Treatments: While the appearance of a parking structure is certainly important, many aesthetic treatments have limited impact on the overall function of the garage. These increase the cost of garage construction, sometimes dramatically so. Whenever possible, owners should closely review the cost and need of such items as façade treatments, stair and railing materials, and other decorative elements.
Structural System (Precast, Structural Steel or Cast-in-Place Concrete): The structural framing system and its durability provisions will affect the initial and long-term maintenance costs. Owners need to be careful that a lower first cost is not offset by future maintenance dollars. An experienced parking design professional can help owners make the choice that best fits their needs and budget.
Most durability discussions revolve around concrete admixtures – silica fume, corrosion inhibitor, slag, fly ash, etc. – as well as coatings on reinforcing steel and steel connections and embedments. Added costs are associated with many of these items. A parking design professional will work with an owner to review the various options, associated costs and long-term benefits.
But several other factors can impact the overall durability of the parking garage that have little or no cost. These include:
Good Drainage: Ponding water on a garage floor will accelerate the corrosion of the reinforcing steel. Providing between 1.5% and 2% slope on all parking decks is recommended to provide good drainage. Sloping parking decks can be provided at minimal added expense, and will save thousands of dollars in costly future repairs.
Good Concrete Cover: Providing an additional ?-inch of concrete cover over the top slab reinforcing steel (resteel) can add years to the lifespan of a garage. Additional cover should especially be considered in corrosive northern or coastal climates. A concrete clear cover of 1? to 2 inches over the top slab resteel is recommended depending on region and type of resteel coating. Typically, the additional cover represents minimal cost to the owner or operator.
Good Detailing Practices: The following detail items cost very little, but provide for a sound garage design that will minimize future maintenance or structural issues:
• Draining water away from expansion joints.
• Isolating restraint members such as elevator shaft walls, ramp walls or crash rails to control cracking.
• Strategically locating shear walls to minimize cracking.
• Providing a wash around columns and walls to keep water away from these items.
• Sealing construction joints to keep water from getting into the joint.
Construction Administration: Proper construction administration is key to ensuring a quality end product. It is therefore important that owners have a qualified parking design professional monitor the construction process carefully so the finished product meets specified requirements and reduces future maintenance costs.
Once a new parking facility has been built, owners and operators can take a few steps to minimize future repairs and add years to the life of the structure, often with little cost. These steps are sometimes overlooked, but they should become part of a regularly-scheduled maintenance plan. This includes:
• Regularly sweeping the garage floor and cleaning/ clearing floor drains.
• Hosing down the parking deck surfaces in the spring to remove salt or de-icing chemicals.
• Having your parking professional perform a periodic walk-through to look for structural deficiencies, leaking or defective expansion joint seals, deteriorating sealants, etc.
In today’s economy, durability and maintenance play a consistently larger role in the parking garage design. Owners and operators must balance the up-front costs of certain decisions with the long-term cost savings. With proper planning and an understanding of the life-cycle costs and benefits, they will find it easier to balance their bottom line.
David Marshall, P.E., is a Principal at THP Limited. He can be contacted at firstname.lastname@example.org.
Article Abstract from March, 2009