Spray polyurethane foam (SPF) can provide an excellent insulating and weatherproofing augmentation to metal buildings. Polyurethane foam forms an integral bond with the metal building surface conforming to irregular surface profiles and providing an effective air seal. Spray polyurethane foam can successfully be applied to most metal building surfaces and components.
SPF may be applied to metal building exteriors or interiors. When applied to exterior surfaces, the SPF must be covered with an elastomeric coating for weather protection. When applied to interior surfaces, the SPF must be covered with a 15-minute thermal barrier for fire protection. Vapor retarders may be required depending on the particulars of the project.
The performance of a spray-applied polyurethane foam insulation system depends on the performance of all the component parts, as well as ambient conditions within and without the building. Therefore, specifiers should consult with the respective material suppliers and the contractor to receive written confirmation of their agreement to all facets of the insulation system. This should include, but not be limited to, material selection, expansion joints, load design, vapor retarders, fire protection (aka thermal barriers), and flashing details.
Below is a decision flow chart to assist in determining under what circumstances protective coatings, vapor retarders, or thermal barriers are likely to be required.