What is the Air Vapor Barrier?? Roofing Membrane still exempt?

Can someone help with Michele's questions? I, too, am looking at the same Carlisle lap sealant, and am not sure how to handle it.

Michele & Emily: On your projects, where is the Carlisle membrane being applied? The November 2010 Addenda that Michele refers to removed roofing sealant categories from the VOC limits tables and noted that the tables exclude “adhesives and sealants integral to the waterproofing system or that are not building related.” I have found no IEQc4.1 Addenda or Interpretations issued since that would change this requirement. LI#1767, issued in April 2007 and still valid for NC-2009, also excludes products applied in locations that are separated from occupied areas of the building by impenetrable walls or decks. Therefore, if the adhesives and sealants are part of your roofing systems, you may exclude them from IEQ4.1 documentation. However, I have seen membrane roofing used at interior applications such as planters and water features. If your project uses interior membranes, the Carlisle VOC data may be relevant.

Concerning Michele’s first question about air & vapor barriers and the boundary separating interior from exterior: The BD+C-2009 Reference Guide sets the boundary at the “waterproofing membrane.” Older rulings also use the term “exterior moisture protection.” This is the outermost layer intended to keep water from entering the building envelope. LEEDv4 is consistent, but more explicit, “The building exterior is defined as everything outside and inclusive of the primary and secondary weatherproofing system, such as waterproofing membranes and air- and water-resistive barrier materials.” Air & water barriers are not necessarily vapor barriers, and vice versa. Vapor retarder placement varies by climate, typically, at the outermost layer only in hot, humid climates. Elsewhere, vapor retarders prevent indoor humidity from condensing inside the wall during cold weather. This has nothing to do with keeping exterior moisture out. Therefore, if the membrane that you are adhering is at the outermost layer, you may exclude it. If the barrier is on the interior side, include the adhesive in your IEQc4.1 documentation.

Thanks to Jon Clifford for his well stated assessment. I helped refine the interior/exterior language in LEEDv4. For the purposes of the Low Emitting Materials credit, the intent is to include emissions sources from parts of the assembly that are likely to migrate into occupied space. The recent proliferation of air and water resistive barrier products merited a definition update. Between the prior interior definition and the LEED 2009 for Healthcare coverage of exterior products, it was unclear where weatherproofing products belonged. For LEED 2009, pay attention to all of the exterior, wet-applied products on Healthcare projects. South Coast Rule 1113 (2004) or California Air Resource Board (CARB) 2007 coating, and South Coast Rule 1168 sealant VOC limits are incorporated by reference. In LEEDv4, CARB 2007 coating and South Coast Rule 1168 sealant limits are expanded to both Healthcare and School projects.

Ok, thanks for the responses, guys. For my project, it seems that as described above, the lap sealant does not need to be reported under EQ Cr 4. This makes things much simpler for me!

Dwayne – Thanks for the updated v4 language. The whole inside-out question always seemed to bog down project teams in the past. The new delineation is much clearer. Moving off-topic, I raised a point in one of my posts above that is a bit problematic. I mentioned interior applications of roofing membranes, which could require membrane adhesives and sealants. Since the 2010 Addenda removed such products from the VOC tables, these categories are not available from pull-downs in the current LEEDonline IEQc4.1 form. Likewise, SCAQMD-1168 Paragraph c1 says that, if an adhesive does not match any of the categories in the SCAQMD charts, the VOC limit is 250g/L. LEEDonline’s IEQc4.1 form does not include this “Other Adhesive” category either. This lapse makes it difficult to classify adhesives for non-porous, non-metal substrates if they do not match any of the “Architectural” or “Specialty” applications listed in the charts. Example: Epoxies made specifically for adhering stone or solid-surface panels. SCAQMD-1113 includes a similar passage concerning non-categorized coating, but I cannot recall ever using a coating that did not fit one of the listed categories. Might the IEQ TAG ultimately address these issues?

Jon: I went ahead and forwarded your comments to the IEQ TAG staff liaison. Sometimes the form issues can be worked out between staff and GBCI. We also have a pending work list for the TAG. Of course everyone involved is in the mad rush to Greenbuild. I'll be at the LEEDUser IEQ hangout with Sara Cederberg on Thursday afternoon at Greenbuild if you want to touch base.

Weatherproofing: In reference to Jon's comments that "“waterproofing membrane..is the outermost layer intended to keep water from entering the building envelope" and “The building exterior is defined as everything outside and inclusive of the primary and secondary weatherproofing system, such as waterproofing membranes and air- and water-resistive barrier materials.” Below grade foundation wall is part of building envelope; this wall separates exterior and the interior; and it has been designed with a "weatherproofing system" to prevent water from entering into the building. So, why is there still confusion as to whether underground [enclosed] parking is included or excluded from EQ low emitting materials? Unless the definition explicitly states weatherproofing system applies to above grade building envelope, underground parking should be considered as part of the building entirety and thus applies to EQ low emitting materials. Any thoughts?

Even if an underground parking garage is within the waterproofing membrane, if the garage is unconditioned (per ASHRAE-90.1), non-regularly occupied (as defined in IEQ Space Matrix), open to the outdoors, and separated from occupied interior space, the garage is NOT interior space and is, therefore, exempt from IEQc4 VOC restrictions. LEED Interpretation #1767 is explicit: http://www.usgbc.org/leed-interpretations?keys=1767. A conditioned basement, on the other hand, would be interior space. IEQc4 credits would apply, and the area of the basement would be included in the project’s gross square-footage.