Can anyone tell me if it is okay to utilize mastic “outside” the building envelope?
Thank you.
You rely on LEEDuser. Can we rely on you?
LEEDuser is supported by our premium members, not by advertisers.
Go premium forForum discussion
NC-v4.1 EQc4: Indoor Air Quality Assessment
See LEEDuser’s guidance on NC-v4.1 EQc4 »
Mastic
Add new comment
To post a comment, you need to register for a LEEDuser Basic membership (free) or login to your existing profile.
Michelle Lockert
January 11, 2024 - 3:39 pm
More specifically, will the toxic off gassing of mastic going to make its way back into the building through the building envelope or make up air and if we are starting to think about those toxic chemicals on the outside as well.
Gregor Braugman
Sustainability Specialist7 thumbs up
January 13, 2024 - 11:04 pm
Michelle,
If the question is whether VOC's from mastics that are applied externally can make their way into the building and cause acute air quality issues for occupants, ... the answer is yes. I say this based on my training as a Certified Indoor Environmentalsit as well as the contact that I've had with professional IAQ Remediators and the field-based stories that they've shared.
However, LEED Residential doesn't have any mandates regarding exterior adhesives, and the last I knew, neither did commercial. In New Mexico where I've been working, most of our projects have to air-seal the envelopes to 3 or 4 ACH to meet code. That greatly reduces the potential for occupant exposure to externally applied products. On the other hand, many of those projects are sealing the envelope to 4 ACH and then ventilating with an exhaust only system which creates a slight negative pressure situation that could pull VOC's through the envelope.
If it was my home, I'd rather focus on installing a balanced ventilation system and then choose exterior mastics based on their durability and moisture sealing performance. Or better yet, I'd rather build earthen walls which could eliminate several IAQ and thermal comfort issues if engineered correctly.
I hope this helps.