Rigid Boardstock Insulation: Friend or Foe?
“When the message is absolutely critical, and not heeding the message increases the likelihood that a disastrous outcome will occur, then repeating the message is (or should be) a professional imperative! This has never been more true than with the issue of specifying and installing rigid boardstock insulation exterior of WRB’s and exterior sheathing on the exterior building envelope.”
The preceding paragraph is from the introduction to John Koester’s new white paper on potential moisture management issues architects, contractors and building owners face when they choose to use rigid boardstock insulation directly behind the exterior veneer of the building envelope (see image below). Normally, we release these articles after they have been published in industry-related magazines; however, this one addresses a topic that is so timely, we are going to release it immediately via our electronic newsletter, our website www.MTIdry.com and our social media sites. There is absolutely no charge nor are there any other conditions to access this article. It is immediately available as a PDF document via the link at the end of this article.
The following are some highlights from the “Exterior Rigid Boardstock Insulation Moisture Management Issues” article.
- Most boardstock rigid insulation has some moisture-resistant characteristics.
- When layered against a weather-resistant barrier (WRB) on exterior sheathing, an undrained cavity/void will be created that may entrap moisture.
- Installing a thickness of rigid boardstock insulation over WRBs and exterior sheathing may have an impact on the fastening patterns and/or structural requirements to secure thin veneers (stucco, adhered thin stone and thin brick and various other siding systems).
- Rigid boardstock insulation may have dynamics of its own.
- Installing a thickness of rigid boardstock insulation over WRBs and exterior sheathing will impact exterior building envelope rough openings…
The article goes far beyond simply pointing out problems. Through the use of text and numerous detailed drawings (17) it shows how to solve or avoid the problems. We hope you find this information helpful, as well as timely. MTI believes that too much time is spent on the energy-saving side of the building envelope detail while often ignoring the moisture management side of the equation.
Building envelope moisture management must be equally involved in the building envelope detail if sustainability and energy efficiency are the goal!
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