Volatile organic compounds, or VOCs, affect indoor air quality, and increasingly, they determine which sealants can even be specified on a project. “Low-VOC” gets used loosely in marketing, but for anyone writing a spec or documenting a greenbuilding credit, the tested number in grams per liter is what actually matters. This bulletin outlines what VOC content means, how it’s measured, and what to check for on a technical data sheet before a sealant is approved for use.

1. What Are VOCs, and Why Do They Matter

Volatile organic compounds are carbon-based compounds that evaporate readily at room temperature as a sealant cures. They matter for two separate reasons:

  • Indoor air quality: VOC off-gassing indoors is associated with odor, eye and respiratory irritation, and general indoor air quality concerns, particularly in occupied or sensitive spaces.
  • Outdoor air quality: Once released, VOCs react with sunlight to form ground-level ozone, which is why they’re regulated as air pollutants, not just an occupant-comfort issue.

2. Regulatory VOC Limits to Know

  • SCAQMD Rule 1168 (South Coast Air Quality Management District, California) is the sealant industry’s de facto national benchmark, often described as the strictest VOC rule in the country.
  • Many specifiers outside California still require “1168-compliant” sealants because it simplifies documentation and reduces project risk.
  • OTC limits (Ozone Transport Commission), covering much of the Northeast and Mid-Atlantic, closely track the same thresholds.
  • Limits vary by sealant subcategory: general architectural sealants, single-ply roofing sealants, and substrate-specific adhesives are not all held to the same number. Always confirm which subcategory applies rather than assuming a single limit covers every product.

3. LEED & Green Building Program Requirements

  • LEED’s Indoor Environmental Quality credit for Low-Emitting Materials requires adhesives and sealants applied inside the weatherproofing envelope to meet SCAQMD Rule 1168 VOC content limits.
  • Materials that are inherently non-emitting (stone, ceramic, glass, unfinished wood) are treated as compliant without testing, but this exemption does not extend to any applied sealant, which must document compliance directly.
  • WELL Building Standard, and healthcare- or school-specific specifications, often layer additional low-emitting-materials requirements on top of LEED’s baseline.

4. Low-VOC vs. Zero-VOC vs. Solvent-Free: Know the Difference

  • Low-VOC means the product meets a specific regulatory or program threshold, not “none,” just “under the limit.”
  • Zero-VOC is marketing language, not a standardized legal term. Always check the actual g/L figure rather than the label claim.
  • Solvent-free describes formulation chemistry, not VOC content directly. Most solvent-free hybrid polymer sealants are naturally low-VOC, but “solvent-free” alone isn’t proof of compliance.
  • The only number that belongs on a submittal is the tested g/L figure from the TDS or SDS.

5. Reading a Technical Data Sheet for VOC Compliance

  • Confirm VOC content is reported in g/L, less water and exempt compounds, the basis SCAQMD requires.
  • Check which rule or program the figure is referenced against (Rule 1168, CARB SCM, LEED v4, WELL).
  • Confirm the test method cited (ASTM D2369 or EPA Method 24) so the number can be verified if a reviewer or inspector asks.
  • Keep the SDS on hand alongside the TDS. Reviewers may request both during submittal or inspection.

6. Practical Jobsite Considerations for Low-VOC Sealants

  • Low-VOC does not always mean low-odor, or vice versa. Verify both if working in occupied space.
  • Cure times and application windows can differ from solvent-based counterparts; always follow the TDS rather than assuming equivalence.
  • Document the product and lot number used on VOC-restricted projects, the same way backer rod or primer use gets documented, to support submittal and inspection records.

Conclusion

VOC content is one of the few sealant specifications that is both regulated and easy to verify, provided the right number is checked at the outset. Confirming a sealant’s tested g/L figure, understanding which rule it’s measured against, and keeping documentation on hand protects a project from delays, resubmittals, and indoor air quality issues discovered after installation.