What does NRCA recommend for buildings with multiple layers of roof systems?

The recommendation from the National Roofing Contractors Association (NRCA) to remove all existing roof layers before installing a replacement is based on the principles of ensuring structural integrity, proper drainage, and effective performance of the new roof system. When multiple layers of roofing material are present, it can complicate inspections and potentially hide issues such as underlying damage or decay that may compromise the roof's functionality.

By removing all existing layers, roofing professionals can assess the condition of the substrate and make any necessary repairs before installing the new roof. This process enhances the longevity and effectiveness of the roofing system, as any deterioration or problems can be addressed at the onset rather than covered up.

The alternatives presented do not align with best practices for roofing installation; for instance, adding layers without inspection could exacerbate underlying issues, and retaining old layers may risk moisture entrapment or insulation breakdown. Installing a single layer over existing materials might seem easier, but it could lead to premature failures or insufficient performance of the new roof system.