Rooftop solar and a new roof in Arlington: sequencing, code setbacks and permits

Roof first, panels first, or together

The county's solar page does not set an order. What it does say is short: "Consider rooftop solar when getting a new roof." It follows that with a request to have a feasibility study done for both. From the code lines below, three decisions interlock whichever order is chosen.

1. The layout decides the roof work. Pathways, ridge setbacks and escape openings mark where panels can and cannot go. Vents, skylights and flashing near the ridge are easier to place once that layout is drawn.
2. Every mount is a roof opening. Section R324.4.3 requires penetrations to be flashed and sealed. Ask who flashes them, and who answers if a leak appears at a mount.
3. The deck and framing may be reviewed. Section R324.4.1 puts structural support on the roof. If decking is replaced, the county's re-roof permit thresholds on the Arlington roofing hub also matter.

These are questions the documents raise, not a ruling on which order is correct for a given roof. A written scope from each trade that names the other is the practical way to keep them from overlapping or leaving a gap. Our roof replacement page explains what a roofing scope should name.

Which rules change with building type

Townhouses

The county solar page keeps any part of the PV system at least 4 feet from a firewall unless the firewall has a parapet rising at least 30 inches above the roof covering. Class A fire-rated PV that serves as the roof covering, with no penetration within 4 feet of the firewall, is the named exception. The 1940s subdivision guide covers houses of that era.

Condo, co-op and apartment buildings

These fall under the commercial list above. The roof also belongs to an association or owner, so the decision path in our condo and co-op roof replacement guide comes first. Flat apartment roofs are the subject of the Clarendon and Lyon Park guide and the Columbia Pike guide.

Historic properties

The county solar page keeps a separate question for solar on historic properties and refers readers to Planning and Community Development. Virginia Code 15.2-2288.7 allows an owner to install a rooftop solar facility on a residential dwelling provided it complies with zoning height and setback rules and any local historic or preservation district provisions. The section is marked on the state site as effective until January 1, 2027, so check the current text, because the state site also lists a version effective January 1, 2027. See the slate roofs and historic buildings guide.

Which county permits a rooftop array needs

Arlington's solar page, read from an archived copy dated October 9, 2024, says a rooftop PV system needs permits from the county's Inspection Services Division. The list depends on the building.

Utility steps that sit outside the roof

The county says the installer sends a Distributed Generation Interconnection Agreement to Dominion Energy, signed by the owner and ideally submitted before installation. After the county's final inspection, a commissioning appointment with Dominion follows, and the meter is exchanged. Dominion has its own process that the county page says it does not explain in full.

The county's tax exemption credit

The page also describes a certified solar equipment exemption under Virginia Code 58.1-3661 and County Code section 20-9. The owner applies to the County Building Official, the credit comes off the real estate tax bill, and it runs for five consecutive years starting the year after approval. The Code of Virginia lets a locality exempt or partly exempt certified solar equipment by ordinance. Ask the county's assessor how it applies before relying on it.

For a re-roof alone, the county's separate residential permit table applies; see the hub guide for it.

What the Virginia residential code says about a rooftop array

Arlington follows the Virginia Residential Code for houses and townhouses. Its section R324 covers solar energy systems, and several of its lines are really roof rules that a roofer and a solar installer both have to work around. The table below reads the 2021 code text as published on UpCodes' Virginia viewer. It states what the section says; it is not an engineering opinion.

Virginia Residential Code 2021, section R324. Source: UpCodes, opened October 26, 2026.

Read the exceptions. Section R324.6 exempts roofs with a slope of 2 in 12 (17 percent) or less from the access, pathway and setback rules. It also says they need not be provided where the code official has determined that rooftop operations will not be employed. Whether either applies is the county's call, not a roofer's or an installer's.

Where a sprinkler system is installed in the dwelling, section R324.6.2.1 offers an alternative ridge setback: 18 inches if the array covers no more than 66 percent of the plan-view roof area, and 36 inches above that. Building-integrated systems that serve as the roof covering, such as photovoltaic shingles and roof panels, are routed to the roof covering provisions of section R905 instead.

Flat roofs, metal roofs and the slope exemption

The residential code's access, pathway and setback rules do not apply to roofs at or under a 2 in 12 slope. That is the text for houses and townhouses; commercial buildings follow the county's roof-plan requirement quoted above. Anyone with a low-slope roof should ask the county in writing which set applies.

Section R324 for rooftop arrays covers structure, fire classification, flashing and pathways rather than rules by roofing material, so the material question is for the manufacturer and installer. Our pages on flat roof systems and metal roofing describe the roofing side. If panels will mount to the roof, ask the solar installer for the mounting system's listing and installation instructions; section R324.3.1 refers to mounting systems listed under UL 2703.

What to ask before anything is ordered

Of the roofer

• Does the written scope name the roof assembly, its fire classification and any decking replacement?
• Who flashes mounts, conduit and vent changes, and in what order do the trades arrive?
• If a solar installer will drill through the new roof, how is that recorded in the scope?

Of the solar installer

• What is the roof layout against the 36-inch pathways and ridge setbacks?
• Who submits the county permits and the Dominion interconnection agreement?
• What is the panel fire class rating, and is the structural package part of the submission?

Of the county

• Which code edition and amendments apply to my address, and does any exception apply?
• Does my historic status change the review? The county solar page refers historic questions to Planning and Community Development.

If you want to talk through the roofing side of the plan, book a phone consultation. We would ask for your address, building type and what is visible from the ground. See also our services.