TPO Roofing in Arlington, VA
The county's roof-covering table is headed "Residential", and the county's own permit page says apartment buildings with three or more dwelling units are treated as commercial. About two in three Arlington homes are in buildings that size, so the table most owners quote may not describe the roof over their heads.
houses and townhouses
3 or more units
Two roofs, two county pages
One TPO membrane, two different permit questions
These are the county's words as they stood in the copies of its pages dated December 30, 2025.
House or townhouse
- Which page
- Residential Building Permit, section "Residential Roof Covering Replacement".
- What it turns on
- How much decking is replaced: none and under 256 square feet are listed as no, over 256 as yes, plywood laid over decking is a call.
- Townhouse twist
- Fire-retardant-treated lumber at original construction means a permit whatever the decking amount.
Building of 3+ units
- Which page
- Commercial Building Permit, because the residential page calls such buildings commercial.
- What it turns on
- The commercial page lists new construction, additions, interior alterations and demolition, trailers and signs. It has no roof-covering row.
- What to do
- Ask Permit Arlington which route your scope takes before anyone is scheduled.
The numbers behind the split
Who actually lives under a rule written for houses?
The Census counts homes, not roofs, so read this as context. In the American Community Survey 2024 five-year estimates Arlington has 121,970 housing units. Of those, 1,283 are in two-unit buildings, 4,317 in buildings of three or four units and 74,987 in buildings of five or more. Adding the last two gives 79,304 units, a computed 65.0 percent in buildings the county's page treats as commercial. Detached houses are 30,238 units and attached townhouse-type homes 10,896. The median unit was built in 1976.
For the full residential table and the permit office, see the Arlington page. This page picks up where that table stops.
What the membrane is
Reading a TPO roof from the deck up
TPO belongs to the thermoplastic family of single-ply membranes, whose sheets can be fused with heat. The other single-ply type in the same code table, EPDM, is a rubber. The membrane is only the top layer, which is why a leak on a large flat roof can trace to a detail rather than the sheet.
Side by side
Where the state exemptions stop for larger buildings
| Question | House or townhouse | Three or more units |
|---|---|---|
| Which county page opens first | Residential Building Permit | Commercial Building Permit |
| State exemption for replacing roof covering | Written for Groups R-3, R-4 and R-5, plus 100 square feet or less in any group | Only the 100 square feet or less clause is written for every group |
| State exemption for decking | 256 square feet or less in R-3, R-4 and R-5, unless fire-rated decking was required | Written for R-3, R-4 and R-5 only, so ask |
| Where the application goes | Online through Permit Arlington | Online through Permit Arlington |
| Who to ask | Permit Arlington Center, 703-228-3800 | Permit Arlington Center, 703-228-3800 |
The state wording is in the Virginia building code's list of work that needs no permit. Which group a particular building falls into is for the building official, so the table says what the text covers, not how your building is classified.
Say the unit count when you call
Open with how many dwelling units the building has. Three or more sends you down the commercial route on the county's own page, and the answer to "does my re-roof need a permit" can change with that one number.
On paper
What to have on the scope for a membrane replacement
- The membrane standardThe building code table lists TPO under ASTM D6878. Ask for it on the data sheet.
- A look under the sheetA neutral industry source advises core cuts to learn whether wet insulation can dry before a re-cover.
- Inspection after the jobThe same trade source says low-slope roofs should be looked at twice a year and after a major storm.
- Drains and flashingsWall flashing, vent collars and drain areas are details worth asking about, because the membrane is only the top layer.
Our flat roof page compares TPO with EPDM, PVC and modified bitumen, and the same questions are worked through for a condominium in TPO roofing in Falls Church.
FAQ
Board and owner questions about low-slope roofs under the county's two permit pages
My condominium has twelve units. Does the county's residential roof table apply?
The county's page says apartment buildings with three or more dwelling units are considered commercial under the Building Code, so the residential table does not describe a building that size. Ask Permit Arlington at 703-228-3800.
I own one townhouse in a row. Which page is mine?
The residential page, and its note about fire-retardant-treated lumber names a townhouse as the example where any decking replacement needs a permit.
Does the commercial permit page say anything about replacing a roof covering?
In the copy dated December 30, 2025, its list of common projects covers new construction, additions, interior alterations, interior demolition, trailers and signs, with no roof-covering row. That is why the county should be asked directly.
Is a rear addition with a flat roof a house roof or a commercial roof?
It follows the building. An addition to a single-family house sits on the residential side of the county's page, and the table turns on how much decking is replaced.
Does the state exemption for 100 square feet cover a small repair on a large building?
The state text exempts replacing 100 square feet or less of roof covering in all groups. Whether a given repair stays under that is a question for the building official, and the county can say how it reads it.
Where is the county permit office?
The county's page lists the Ellen M. Bozman Government Center, 2100 Clarendon Blvd., as its main address. Permit questions go to the Permit Arlington Center at 703-228-3800, and applications go in online, so confirm whether a visit is needed before you go.
Nearby
Next-door pages that handle the same building-size question
Back to Arlington for the full residential table, or see Falls Church and Washington DC. Browse the materials guide, our service areas or about King's Roofing.
Talk through the next step
Tell us how many units sit under the roof
The unit count decides which county page applies. Give us the street address, the building type and where water shows inside, and we will say what to confirm with the county first.
9220 Topaz St, Fairfax, VA 22031
Mon to Fri 7 AM to 8:30 PM, Sat 7 AM to 8 PM, closed Sunday