EPDM Roofing in Rockville, MD: Colour Is a Code Question
Rubber roof sheets come in black and in white. In the City of Rockville, a low-slope roof on an apartment or commercial building has to satisfy a reflectance test written into the City Code, and that is where the colour of the sheet stops being a matter of taste.
Ordinance 06-24 added section 1507.1.3 to the building code the City applies to non-house buildings. For roofs under a 2:12 slope, at least 75 percent of the roof surface has to be covered with products that meet the listed criteria, one of which is an initial solar reflective index (SRI) of 78.
- Ask which listed criterion your sheet is being checked against.
- Ask for the sheet's rated initial value in writing, not a colour name.
- A house or townhouse roof sits under a different article.
What the ordinance actually prints
The new section is headed "Cool roof requirements." It covers roof coverings on slopes of less than two units vertical in twelve horizontal, which the text itself translates as under 17 percent, for buildings and covered parking. The share that counts is 75 percent of the entire roof surface, leaving out roof penetrations, onsite renewable energy systems and vegetated roofing.
The criterion the ordinance prints is "a minimum initial solar reflective index (SRI) of 78." That item is numbered 3 and ends with "or," followed by asterisks, so the copy posted online does not show items 1 and 2. What they require is not visible there, so do not assume SRI is the only route. Ask the Inspection Services Division for the full text of 1507.1.3.
Where the rule does not reach
The section is added to the IBC, the code for buildings other than one- and two-family houses and townhouses. The City's permit exemption for replacing roof covering is limited to those R-3 houses and townhouses, and only for in-kind work that leaves the deck and structure alone. So the cool-roof test and that exemption describe two different groups of buildings.
The City's Administrative Bulletin 2024-01 describes the roofing exemption as applying in limited cases for group R-3 structures. The permit table on our Rockville page covers the house side; this page stays with the membrane side.
Why EPDM, of all sheets, raises the colour question
Trade association guidance says sheet membranes come in black and white and in many other colours. EPDM is the rubber one, made to its own ASTM standard, D4637, a handle that lives on the data sheet rather than on the surface of the roof. Because the same rubber chemistry is offered in more than one colour, "EPDM" alone does not tell a plan reviewer how reflective the sheet is, and a dark sheet is the version most likely to need a second look against the SRI line.
No reflectance number is printed for black or white EPDM here. Those values belong to a specific product's rated listing, and the sections below say where to find one.
Where the City asks about SRI before you file
The City's residential building permit submittal requirements ask for "all information on roofing system," and the list in the parentheses ends with solar reflectance (SRI), after flame spread, material, type, class, slope, squares and ice barrier. A reflectance value is therefore part of the paperwork conversation in Rockville even before a roof is large enough to trigger the 75 percent test.
Historic districts add a second approval
The same section says replacement of a roof in a Historic District Zone, including any change to design or materials, must be approved by the Historic District Commission. A switch from black to white sheet on a building inside a district is a change of material or appearance, so the Historic Preservation Division is a call to make before ordering.
What gets measured
The top layer is the only one the reflectance test reads
The ordinance counts surface, so the product on top of the stack is what is listed and checked. Insulation below it does not change the sheet's rated reflectance. A cover board or extra insulation can change how the roof is built, but not what the top face reflects.
The Cool Roof Rating Council keeps the public directory of measured values. Its own FAQ says it does not define "cool" and leaves that to the code bodies that reference it, so a product appearing in the directory is not the same as meeting Rockville's line. Match the listed initial value to the number the City uses.
Before the sheet is ordered
Four things to settle with the City and the supplier
1. Which code
Confirm with the Inspection Services Division whether your building is under the IBC or the residential article.
2. Which criterion
Get the full text of 1507.1.3 and see which listed items your sheet can meet.
3. The listing
Ask for the product's rated initial SRI from its CRRC listing, in writing.
4. The district
If the building is in a local historic district, ask about the Commission first.
FAQ
Rubber roof sheets and the Rockville reflectance line
Is black EPDM allowed on a Rockville apartment roof?
That depends on whether the product's rated initial value meets a criterion in section 1507.1.3 on at least 75 percent of the roof surface. Black EPDM's rated value is on the product listing, so ask the supplier for it and ask the City how it reads against the line.
Does a white EPDM sheet automatically pass?
No. The ordinance prints a number, SRI 78, and the sheet has to be listed at or above it for the share of roof it counts. Colour is a clue, the rated value is the answer.
What counts toward the 75 percent?
The ordinance measures the entire roof surface, not counting penetrations, onsite renewable energy systems and vegetated roofing. How the City treats walkway pads or mechanical curbs is a question for the division.
Does this apply to my house's flat porch roof?
The section is added to the IBC, while houses fall under the one- and two-family article. The City's checklist for house permits still asks for solar reflectance, so be ready with a value if a permit is needed.
Is the CRRC listing enough on its own?
It is the measured value, but the council says it does not decide what counts as cool. The City's code and its Inspection Services Division decide that.
Why can't I find the other items under 1507.1.3?
The ordinance as posted prints item 3 and then asterisks, which marks text left out of the excerpt. Ask the division for the full section rather than relying on a summary.
Is a roof in a historic district treated the same way?
The same section requires Commission approval of roof replacement there, including a change in design or materials, so the district review comes first.
Nearby
Other flat-roof pages that sit beside this one
The Rockville page holds the City office table and historic review. Our flat roof page compares membranes. For rubber sheet elsewhere see EPDM in Reston, and for a white sheet and a different permit story see TPO in Falls Church. Montgomery County neighbors are on the Kensington page.
Talk through the next step
Talk through your roof with King's Roofing
Share the address, what you are seeing on the roof and the decision you need to make. We will tell you what to expect before anything is scheduled.
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