Air Tightness of Two Walls Sprayed with Polyurethane Foam Insulation

Abstract

Use of sprayed-in foam insulation may improve the air tightness of frame wall systems. There are concerns: (1) whether construction moisture that is trapped in lumber framing will be able to dissipate sufficiently to prevent decay, and (2) whether these walls can maintain their air tightness and energy efficiency over time. To assess some of these issues, high moisture content wood was used for the construction of two walls insulated with polyurethane foam insulation. Tests showed that the air tightness of the walls was not affected by the drying of the lumber. But, the slow drying rates experienced by both test walls suggests that it would be unwise to use this type of foam insulation with framing that has a high moisture content because of the danger of creating conditions conducive to decay of wood.