EPDM Roofing in Tysons, VA: What the County's Rain Goals Ask of a Roof
Tysons has a county-written goal for rainfall, and the county's own slides name roofs, green roofs and rooftop water reuse as ways to meet it. Those papers never name a roofing membrane. Read them closely and they turn into a short list of questions for anyone weighing a black rubber EPDM roof on a Tysons building.
The county's own words
How much rain does Fairfax County expect a Tysons site to keep?
"At a minimum, the first inch of rainfall should be retained on-site through infiltration, evapotranspiration and/or reuse"
County Department of Public Works and Environmental Services, Urban Stormwater Concepts for Tysons Corner, April 2012, slide 3, quoting the Tysons Comprehensive Plan. Read October 15, 2026.
Two columns
Where do the county's Tysons papers stop and your bid documents begin?
What the papers describe
- Roof rainfall
- The county's flow chart tells designers to capture all or part of roof rainfall and work out how to reuse it, adding that year-round permanent uses are needed for stormwater credit.
- Green roofs
- A compliance table lists a runoff reduction of 45 to 60 percent for a green roof under the Virginia Stormwater Regulation. Its footnote says the figure is tied to phosphorus, so the percentages are lower.
- Planting
- The planting chapter says a green roof can be as simple as sedum sod over minimal soil or as intricate as raised beds with trees.
- Upkeep
- It suggests paths that serve both the garden and the building's mechanical maintenance.
What they leave to the drawings
- Membrane
- None is named in the chapters and slides opened for this page.
- Seams
- Silent. Nothing says how a sheet joint is reached once soil, pavers or planters sit on it.
- Existing buildings
- Silent on re-roofing. The planting chapter says to bring green roof ideas in early, so the proper infrastructure is included.
- Who decides
- A board, landlord or owner, as our Tysons guide sets out.
Before the call
What should a Tysons owner have in hand before asking about an EPDM roof?
- What the roof is forOnly keeping the top floor dry, or also holding rain, carrying plants or serving as a terrace. The county papers speak to the second group.
- A drawing of drains and overflowAn asphalt-roofing trade bulletin calls water that stays 48 hours or longer ponding, and sets "blue roofs" apart as roofs made on purpose to hold and slow drainage.
- How the sheet joints are madeEPDM laps are glued or taped. An NRCA library abstract from 1991 says many EPDM problems involved lap seams. It is old, so treat it as a question, not a verdict.
- The standard on the data sheetThe building code's single-ply table pairs rubber EPDM with ASTM D4637. A bid that says only "rubber roof" has not named it.
- What lies under the old sheetThe single-ply trade association SPRI advises core cuts and a moisture survey before re-covering over existing insulation.
- Who can signThe condominium instruments or the lease decide who orders the work, and the county permit table says which questions go to Land Development Services.
Whom to ask
In what order do these questions get answered?
First: whoever owns the roof
A board, a landlord or an owner names the roof area and says whether any part is meant to hold water or plants.
Second: county Land Development Services
Ask whether the Tysons stormwater goals reach re-covering a standing building. The papers read as silent.
Stop here if the answer is noThird: the designer and every bidder
Put the seam, drain and data sheet questions in the same words to each, then compare written answers.
Soil and pavers hide the parts SPRI says to look at
SPRI's maintenance advice for low-slope roofs is a look at least twice a year and after any major storm, with open drains and tight flashings around penetrations. Our reading: a planted roof needs the access to do that written into the design, which is why the planting chapter asks for maintenance paths. The chapter does not say what lies beneath them.
FAQ
Questions Tysons owners ask about EPDM and the county's rain goals
Does Tysons call for EPDM or any other roofing membrane?
Nothing opened for this page does. The county's stormwater slides and design chapters describe what a roof might do with rain and plants, and leave the sheet to the designer.
Do the county's rain goals apply when an existing roof is replaced?
The papers read as guidance for development plans and say nothing about re-covering a standing roof. The county's Land Development Services at 703-222-0801 can say what applies to your parcel.
Are the stormwater slides still the county's current position?
They are dated April 2012 and the county's Tysons environmental stewardship page still links them. They quote the Plan, so ask the county whether its wording has since changed.
Is 45 to 60 percent what a Tysons green roof achieves?
No. It is a credit in a county compliance table, with the footnote that it is tied to phosphorus. The planting chapter separately says green roofs can treat as much as half of roof drainage. Neither measures a particular roof.
Do the Guidelines make planting a roof mandatory?
Their introduction says they do not dictate a particular architectural style and that comparable alternatives may be considered. The planting text is a list of design suggestions.
Does a planted roof change the waterproof layer beneath it?
The county text does not say. It is a question for the architect and the membrane maker, and the planting chapter wants the infrastructure considered at the start.
How is a roof meant to hold water different from a roof with a low spot?
The trade bulletin quoted above treats a blue roof as designed to hold water briefly and ponding as an unplanned problem. Ask which one your drawings describe.
Where do other low-slope roofs in and around Tysons fit?
The same county's rooftop wording from the Urban Design Guidelines is read for a plastic sheet on our PVC roofs in Tysons page. Low-slope coverings are compared on flat roof, and the TPO and EPDM guide covers the regional basics. Neighbours with their own EPDM pages: Reston and McLean.
Official pages used
Read on October 15, 2026: Urban Stormwater Concepts for Tysons Corner, Tysons stormwater compliance tools, Urban Design Guidelines chapter 3, chapter 1, SPRI FAQ and ARMA ponding bulletin.
Talk through the next step
Bring the roof area and the drawings
Tell us whether the roof is a tower top, a podium, a deck or a plant area, who owns it, and send any drainage drawing you hold. That is enough for a useful first call.
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