Why is it Raining in my Parking Structure?

parking structure rainingBy Scott Weiland

Ever wonder why it is raining inside your parking structure?  Well, it is a sign that your parking structure needs attention. Water is the No. 1 cause of parking structure deterioration. Water-saturated concrete can freeze, expand, and spall. Combined with oxygen, water can also cause corrosion of the concrete reinforcing, accelerated by exposure to deicing salts. As reinforcing steel expands as it rusts, this process also leads to concrete spalling. Spalled concrete provides less cover or protection of the structure which leads to further (and accelerated) deterioration if not repaired in a timely manner.

The top level of your parking structure not only provides possibly the least desirable parking spaces, it also serves as the roof of the facility. Controlling water in the form of rain or melting snow at this level is the least expensive way to extend the life of your parking structure and minimize maintenance costs. Controlling the water runoff involves shedding water to drains as quickly as possible.

Ponding water is unacceptable as it saturates the concrete and leaks to lower levels. The installation of supplemental drains can easily and permanently address ponding. Urethane joint sealant at the top level is exposed to UV sunlight and tends to break down within a few years. The breakdown of this product leads to cracks in the sealant allowing leaks to the levels below. This leads to degradation at lower levels like that described above at the top level.

Therefore, it is important to visually inspect joint sealants annually and budget a portion of joint sealant replacement approximately every three years at the top level. Urethane joint sealant replacement will cost approximately $4.50 per linear foot but provides one of the best returns on investment when it comes to parking structure maintenance.

Given the accelerated rate of parking structure deterioration, this is cheap insurance against having to perform more expensive repairs in the future.

Scott Weiland, PE, is founder of Innovative Engineering, Inc. He will present on this topic during the 2020 IPMI Virtual Parking & Mobility Conference & Expo, June 1-2, wherever you are. Click here for details and to register.