Architects and engineers may spend hours designing sealant joints for curtain walls or highways. Residential buildings will never receive that kind of attention, but there are several points to keep in mind if you want your air sealing work to have a chance of lasting as long as the building. Joint Design A sealant must stick to the substrate (adhesion) and hold itself together (cohesion). This requires a minimum amount of sealant. Usually a joint needs to be at least 1/4 inch wide and 1/8 inch deep. Some sealants, however, will work in smaller joints. Check with the manufacturer for the ideal size of the joint for the particular sealant you are using. Joints can also be too big. If there's too
