epoxy for ceramic joints

Epoxy grout used at ceramic tile qualifies as “Ceramic Tile Adhesive,” so the VOC limit is 65g/L. If your parking garage is unconditioned and open to the outdoors, it is exempt from IEQc4 VOC restrictions. See LEED Interpretation #1767: http://www.usgbc.org/leed-interpretations?keys=1767

Is the garage separated from the occupied, conditioned building by solid, impenetrable walls? If so, it does not matter that the garage is underground. LI#1767 states that an underground garage that is unconditioned and open to the exterior is not technically interior space. IEQc4 VOC limits only apply to interior space.

If the openings between the garage and the building have self-closing doors to prevent automotive exhaust from entering the building, then this still qualifies as an interior/exterior separation. For sealants that fill, seal, or waterproof gaps or joints between surfaces, the VOC limit is 250g/L for Architectural Sealants used within the weatherproof enclosure. However, if you are asking about liquid sealers applied to concrete to resist water, alkalies, acids, ultraviolet light, or staining, these products would be Waterproofing Concrete/Masonry Sealers. According to IEQc4.2, the VOC limit is 400g/L for concrete sealers used inside the weatherproof enclosure.

What is the rational of having this product applicable to below grade parkade slabs since the parkade below grade separated from the above grade structures by fire-rated slab, walls, and self-closing doors; and separate ventilation system?