Masonry Magazine November 2009 Page. 26
The Skinny on Insulation
BY GREGG HODGSON
Mason contractors have a lot on their plates. You have to consider everything from A to Z as it affects your projects. So, what about insulation? Think it's not really your concern? Think again. Masonry spoke with an expert in the area of insulation to garner the information you need to know. Richard S. Shupe is president of Oxford, Conn.-based Connecticut Insulation Distributors Corp. (cidconline.net) He has been in the construction business since 1970, having been with CIDC for 15 years. Following is what he had to say.
Masonry: Why should a mason contractor care about insulation?
Richard Shupe: Insulation is an important component of the building's envelope. If the mason is a conscientious craftsman, he feels some ownership of the entire wall system, not just his portion of it. Insulation is a part of the building's system of air barriers, moisture barriers, fire-resistive barriers, sound barriers, and water-resistive barriers. These barriers are designed to protect the interior from unwanted external conditions.
Masonry: In non-technical words, why are those barriers needed?
Shupe: An air barrier prevents the passage of air through [the wall). Warm air has a tendency to move toward cool air, so you want a barrier that will keep warm interior air from escaping in cold weather, and conditioned air from becoming warmed by outside air in hot weather. Insulation materials contain tiny air spaces within them that thwart warm air from moving toward cooler air, in either direction.
"In the Pink" Insulation, like this row of rigid extruded polyethylene panels, stands passively in the masonry wall cavity, yet plays an active role in the building's life. Its millions of tiny air spaces keep heat from escaping in winter and invading in summer, boosting interior comfort and cutting energy costs.
A vapor barrier keeps water vapor from going where you don't want it. Vapor tends to move toward dryer air. In winter, when outdoor temperatures and humidity are low, vapor tries to drive itself through the interior walls to the outdoors, and the reverse occurs in the high humidity of summer. Neither is desirable, and when the vapors condense on cooler surfaces, it can cause moisture damage. In masonry wall systems, rigid insulation often can serve as a vapor barrier, although important exceptions exist involving climate and the building's pressurization. Many vapor barriers are peel-and-stick membranes, but I find some of the liquid membranes are extremely user-friendly.
Water-resistive barriers prevent bulk water from entering the interior spaces. As all masons know, water can occur in any wall system, even brick or block. A water-resistive barrier intercepts that water and lets it exit the wall, usually through weep holes.