The Air Apparent
Our latest continuing-education seminar explored the complexities of air, water, and vapor barriers in building envelope design.
As wall types have become more complex and energy efficiency standards more stringent, the need for effective barriers against air and water penetration is more important than ever. Han Ling from Henry Company explained this imperative in Superstructures’ latest continuing-education seminar presented in our classroom on June 19. His talk was a primer on the functions and interactions of various kinds of barriers, plus some surprising revelations.
While you might reasonably assume that mold problems would decrease as building materials and technology advance, the opposite is true: more complex wall types mean more opportunities for intra-wall condensation and thus, mold growth over time. Mr. Ling also underscored the benefits of fully adhered barriers versus those that are mechanically attached (a better seal and fewer penetrations).
Keeping outside air out is equally important. “Wind washing,” the phenomenon when air flows around insulating material, can reduce the insulation’s R-value by up to 90%!
Speaking of heat, the combination of flammable insulation and air space in a building envelope can create a “chimney” effect that allows fire to quickly climb an outside wall. Fortunately, New York State requires testing of envelope designs containing combustible water-resistive barriers to comply with NFPA method 285, avoiding the risk of such accidental chimney effects (see ICC 1403.5).
Save the date for our next seminar, “Everything You Always Wanted to Know About Infrared Thermography (and Electrical Impedance) Testing” with Barry Drogin on Wednesday, July 17, 2019, 6 – 7 pm. Follow us on LinkedIn for more details to come.