THE CHALLENGE
CBI provided design services associated with the investigation of exterior wall failures. Several pieces of the aggregate finish fell off the building or became loose after a series of rain storms including a hurricane. These pieces were completely delaminated and there was concern that much of the building exterior may be delaminating.
CBI’S SOLUTION
CBI made test cuts in the stucco and sounded the walls to determine the existing conditions. The failing panels consisted of delamination of the 1/8” thick finish coat rather than the panels themselves. The stucco finish was debonding from the base due to water penetration and thermal cycling.
CBI recommended adding a new external wall system over the existing materials. The most practical option is to install an exterior insulation and finishing system (EIFS). The EIFS system would include new insulation adhered to the existing stucco after any loose delaminated material has been removed. This would not cut or penetrate the asbestos panels so it would not require containment. The EIFS insulation would be adhered to the panels with glue and covered with a synthetic stucco finish system reinforced with fiber mesh reinforcing. This would add some insulation to the walls and provide a look comparable to the existing wall system. The insulation would help protect the existing stucco finish from thermal cycling and water to address the debonding condition. Prior to adhering the insulation panels, the existing panels would be coated with a liquid waterproofing membrane in case of water leakage behind the system.
