Is Your Roof Coating Legal to Apply in PA, NJ, DE, MD and Ohio? VOC Limits Explained for Building Owners

Yes, a roof coating can be illegal to apply. Pennsylvania, New Jersey, Delaware, Maryland and Ohio all regulate how much volatile organic compound (VOC) a roof coating can contain. The common ceiling for the “roof coatings” category is 250 grams per liter, and some states are moving lower. A quality solvent-free, high-solids silicone typically comes in far under that, often below 50 g/L. Some cheaper solvent-borne products sit right at the line, and that’s where problems start.

Most building owners never see this number. It matters anyway: if a contractor applies a non-compliant product or thins a compliant one past its limit, the coating is out of compliance on your roof. Here’s what the rules say, how to read the VOC number on a data sheet, and what to ask before you sign.

Where the 250 g/L rule comes from

Roof coatings fall under what regulators call architectural and industrial maintenance (AIM) coatings rules. In the Northeast and Mid-Atlantic, those rules are based on model rules written by the Ozone Transport Commission, a group of states that coordinate on smog. VOCs evaporate from wet coatings and help form ground-level ozone, so states cap how much a product can contain.

• Pennsylvania adopted its AIM rule (25 Pa. Code Chapter 130) in 2005, with a 250 g/L limit for roof coatings.
• Ohio’s current rule (Ohio Admin. Code 3745-113-03, updated December 2022) keeps “roof coatings” at 250 g/L. It sets bituminous (asphalt) roof coatings at 270 g/L and aluminum roof coatings at 450 g/L as of January 2024.
• Maryland and Delaware have adopted the newer, stricter OTC “Phase II” model rule, and New Jersey proposed tighter architectural-coatings limits in 2024.

The details differ by state and change over time, so the right answer for a specific product and address is always the manufacturer’s compliance statement. But 250 g/L is the number to know. A silicone coating that’s well under it has room to spare.

Two rules that catch contractors, not manufacturers

Most VOC rules regulate the product. Two provisions regulate the application, and those are the ones that matter on a job site.

1. No thinning past the limit. Both Pennsylvania’s and Ohio’s rules prohibit applying a coating that has been thinned to exceed its VOC limit. Silicone can get thick in cold weather, and a crew in a hurry may add solvent to make it spray. If the product started at 240 g/L, a little solvent puts it over. High-solids silicones that start near 50 g/L don’t have that problem, and most manufacturers say not to thin them at all.

2. The most restrictive category wins. If a product is labeled or marketed for more than one use, the lowest applicable limit applies. A product sold as both a “roof coating” and a “waterproofing” or “primer” may be held to the tighter number. This is mostly a manufacturer issue, but it’s one more reason to use products built and labeled specifically for commercial roof restoration.

How to read the VOC number on a data sheet

Every silicone roof coating’s technical data sheet lists VOC content, usually in grams per liter (g/L) or pounds per gallon (1 lb/gal ≈ 120 g/L). Here’s how to interpret it:

• Under 50 g/L: typical of solvent-free, high-solids silicone. Comfortably under every limit discussed above, with lower odor during application.
• 50–200 g/L: compliant under a 250 g/L limit, but check the specific state rule if you’re in a stricter jurisdiction.
• Right at 250 g/L: legal under most current limits, but there’s no margin for thinning and no margin if a state tightens its rule.

VOC content and solids content are linked. A coating that’s mostly solids has less solvent to evaporate, which is also why it builds more dry film per gallon. We explain that math in what “96% solids” means on a silicone coating. When you’re comparing products, check that the data sheet also references the industry silicone standard. Our ASTM D6694 explainer covers what to look for.

One caution: “VOC-compliant” doesn’t mean “no odor.” Some products meet the limit by using solvents that regulators exempt from the VOC count but that still smell. If you’re coating over an occupied office, school or healthcare building, read our guide to odor, ventilation and HVAC intakes.

Three VOC questions to ask before you sign a coating bid

1. What is the exact product, and what is its VOC content in g/L? Get the name and data sheet, not just “silicone.”
2. Will the product be thinned on site? The right answer for a high-solids silicone is no. If thinning is planned, ask how they’ll stay under the limit.
3. Is the product compliant in our state, and will you put that in writing? A reputable contractor or manufacturer rep can answer in one email.

A low bid built on a cheaper solvent-borne product isn’t necessarily illegal. But it often means lower solids, more gallons to reach the warranty thickness, and more odor. The per-gallon savings can disappear by the time the job is done.

Get a compliant restoration quote for your roof

We specify solvent-free, high-solids silicone on commercial restorations across Pennsylvania, New Jersey, Delaware, Maryland, West Virginia and Ohio. A silicone restoration typically runs $3–6 per square foot versus $10–16 for tear-off and replacement, a 50–70% savings. Most roofs are done in 1–3 days, with warranties up to 20 years and silicone’s resistance to UV and ponding water that acrylics can’t match. See the full breakdown on our silicone roof coating cost page.

Next step: request a free roof assessment. We’ll inspect the roof, tell you whether it’s a restoration candidate, and include the product data sheet with the VOC content in your quote, so you know exactly what’s going on your building.