By: Joe Czaszynski
October 27, 2020
Coatings systems are a great way to protect your concrete parking deck and/or structure. Coating systems can be beneficial in many ways, but especially towards the end of its useful life. For example, a new or additional layer of coating can be applied atop the system and extend its service life as well as warranty period. However, before an overcoat can be applied, several things must be reviewed to determine if an overcoat is a viable option, or if removal of the existing system and installation of a new system is required.
The first item that is helpful in making this decision is having an accurate service record. As with most building components, coating systems require regular inspections and maintenance at least once a year. If a proper service record is kept, design professionals will be able to easily recognize issues or failures that have previously occurred with the existing coating system, causes of those conditions, and what was done to correct them. Typically, maintenance work and inspections come with written reports and recommendations; not only are these reports helpful for the Building Owner to see exactly what was done, but they help keep an organized paper trail. This paper trail is extremely helpful to a design professional when they are determining if a new system is needed or if an overcoat can be provided as an option.
Another helpful variable when identifying if an overcoat is possible, is to have the existing coating’s manufacturer representative present during the on-site evaluation. The manufacturer’s representative should have a wide range of knowledge about the system. To list a few, they should be able to provide insight on the system in use, what system might be compatible as an overcoat if the existing system is discontinued, the preparation required to receive an overcoat, and warranty options. While manufacturer representatives provide input for product application the design professional to will select a system that would be most beneficial for the client.
Another factor that must be taken into consideration is the condition of the structure and substrate that will receive the product application. If the structure is in a state of disrepair or deterioration, repairs to these components would likely require the replacement of the coating system. Replacement of existing drainage system or roof accessories could also require the replacement of the existing system in its entirety in lieu of an overcoat. The drains and accessories require flashing and the flashing system will tie into the coating system. In some cases, it is possible to combine the flashing system with an overcoat system, but this will have to be determined by the design professional and manufacturer’s representative.
If an overcoat is selected, several pull tests would be required to determine if the existing coating system is properly adhered to the substrate. The pull test would be performed by an experienced contractor and the test would be performed to the limits required by the manufacturer. The design professional would identify where the pull tests should occur, which typically occur in high traffic areas or areas that see the most use. If the existing coating passes the required PSI pull test, an overcoat may be installed.
A full system replacement would be specified if there has been an overcoat installed previously. Proper adhesion between multiple layers of coating begins to lessen, making an overcoat build up over several existing layers an undesirable solution. If an existing coating system is delaminating from the substrate, this would indicate other issues, either with the coating system and/or the substrate itself; installing an overcoat atop a system in this condition should be avoided. If multiple leaks are present within an existing coating system, it is likely that the coating has systemic failure and should be replaced. Over time, water infiltration will diminish the integrity of a concrete structure, by causing steel reinforcement to corrode. If not addressed prior to the installation of a new coating system, the deteriorated concrete/reinforcement could deteriorate further and cause the coating system to prematurely fail.
A qualified building envelope professional with expertise in garage restoration is well suited to observe the state of the current coating system and substrate, as these components are indicators whether an overcoat system is the best option. While an overcoat system may provide upfront cost savings, the overlooking the factors that may lead to premature failure could end up in compounding the lifecycle costs. It is important for Building Owners to consider the aforementioned items when making a choice between a new coating system or coating over the existing; a well informed decision will help protect your property and capital for essential lifecycle repairs.
