1,053 owner-occupied
689 of them in buildings of 50 or more, 206 in buildings of 20 to 49, and 158 in smaller ones.
Who decides on a TPO roof over a Potomac condo or apartment building?
Most Potomac roofs belong to one household. A smaller group sits over many, and that group is where a single-ply membrane such as TPO is most often discussed. These are the questions that come first.
Group one
Whose roof is it when a building holds dozens of homes?
How many Potomac homes share a roof with several others?
The Census Bureau's American Community Survey, 2020 to 2024, counts 2,340 homes in buildings of five or more units in the Potomac place, out of 16,796. Of those, 1,593 are in buildings of fifty or more. The count is of homes, so the number of roofs is far smaller, and the table does not say how many of those roofs are flat.
Do the people under those roofs rent or own?
Both, in nearly equal numbers. A second table cuts occupied homes by building size and tenure.
1,188 renter-occupied
871 in buildings of 50 or more, 200 in buildings of 20 to 49, and 117 in smaller ones.
2,241 occupied homes
Renters are 53 percent of occupied homes in these buildings, against 15 percent of all occupied Potomac homes.
The survey does not say whether an owned home is a condominium, so it cannot tell you who legally holds the roof. Our reading: where homes are owned, ask the association or its manager; where they are rented, ask the building's owner.
Does a village-center commercial building belong in the same conversation?
It often has the same kind of roof question. Wikipedia's Potomac article says many original buildings in Potomac Village were demolished for strip malls and modern office buildings. The pages read say nothing about what those roofs are made of, and the Census counts homes, not shops, so we make no claim about them. What they share with an apartment block is a large, shared roof with more than one party who cares about it.
What the county pages leave out
The commercial permit list names no roof job at all
The Department of Permitting Services lists its commercial permits on one page: addition, alteration, change of use, fast track, demolition, foundation, new building, ownership unit, retaining wall, fence, restaurant interior alteration, sign, sheeting and shoring, solar, EV charging, pool, use and occupancy, and wireless. The word roof does not appear on that page. Whether a covering-only job on a larger building needs a permit is therefore a question the page does not answer.
Group two
Which county page mentions a roof, which shuts one out, and who is left?
Where a roof appears: the interior alteration page
As structure, not covering. Alterations to an existing structure need drawings stating dead, live and snow load assumptions and the weight of new mechanical units, with calculations where a rooftop unit is attached. The same list asks for an evaluation of existing roofs against drifting snow from higher roofs built within twenty feet. That concerns loads, not the choice of membrane.
Where a roof is shut out: the fast-track guide
The guide is for small interior alterations. It lists "any exterior alterations or site changes" among the projects that do not qualify, and also excludes new roof-mounted equipment over 300 pounds and new roof framing openings over six by six inches. Neither page addresses re-covering.
Who still has a say: the association or building owner
The county's homeowner page says its permit information leaves out municipality and association rules, so those are checked separately. That page is written for a home or property and carries no matching sentence for a larger building. Ask the permitting office about your address, and ask the owner or manager what their own approval takes. The Potomac page lists which office answers which question.
Group three
What does TPO ask of a flat roof on a building like this?
Is the roof flat enough, or too flat, for a membrane to be the question?
The 2021 International Building Code sets a design slope of at least one quarter unit in twelve, a 2 percent slope, for single-ply roofing on new design. Whether an existing Potomac roof counts as low-slope, and what applies when it is replaced, is for the building official. See flat roofs for how re-covering is treated.
Is a white membrane required here?
Not by the model code table we read. The 2021 energy code's roof reflectance rule covers Climate Zones 0 through 3 only, and its table places Montgomery County in Zone 4A. Local amendments were not checked, so we write "not required by that table" and not "not required by law."
What should a written scope say about the edges?
On a roof with a slope under 2:12, the code asks that metal edge systems be designed for wind loads and tested to ANSI/SPRI ES-1. On a tall building the perimeter is where loose metal gets noticed from below, so ask whose test the proposed edge detail meets.
Neighbours with their own pages: TPO roofs in Rockville, where a city ordinance changes the question, and EPDM roofs in Bethesda, which covers the county's 2021 code adoption. The materials guide is here.
Pages used, checked 2026-10-12: Census Reporter, Potomac tables B25024 and B25032; county commercial permits; commercial interior alteration; commercial fast track guide; county home improvements; Potomac, Maryland. The building-code and energy-code text is from the 2021 ICC editions, read on 2026-10-11.
Talk through the next step
Bring the building, not just the roof
Tell us the street, how many homes sit under the roof and who manages the building. We will help you work out whether a flat-roof membrane is even the question before anything is scoped.
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