What plans does Fairfax County require for a deck permit?

Fairfax County publishes Typical Deck Details, a pre-approved set of deck drawings based on the 2021 Virginia Residential Code. ^S1S2 Use them for a residential, single-level deck. ^S1 Otherwise, submit your own plans showing foundation, framing, ledger attachment, guards and stairs, plus a site-related plan or plat. ^S3S4

Does Fairfax County have a deck detail handout?

Yes. "Fairfax County, Virginia Typical Deck Details" is version 2021.0, dated 1/5/2024. ^S1 The county lists typical details for decks, finished basements, carport enclosures and retaining walls, and says they can be used in place of an architectural plan submission. ^S2 The handout also exists in several languages and as a separate version for manufactured homes. ^S5

The rules for using it:

• It applies to residential, single-level decks only. ^S1
• Construction cannot deviate from the details without prior county approval. ^S1
• A copy with Section 10 ("Complete My Deck") filled in must be on the job site at each inspection. ^S1
• It cannot be used for multi-level decks that share posts and footings. ^S1
• It is not approved for privacy screens, planters, built-in seating, surface-mounted guardrail posts or hot tubs. ^S1

Fairfax also lists decks among projects eligible for Fast Track priority plan review. ^S2

What goes on a custom deck plan?

If you are not using the typical details, the county's checklist for additions, decks and porches asks for PDF plans on 11 by 17 inch sheets at 1/4 inch = 1 foot, a site-related plan, a foundation plan, framing plans, and columns, beams and header sizes. ^S3 The checklist also lists a digital seal and signature, if applicable. ^S3 The checklist PDF is marked "Updated June 2021," so check with the county that it is still current.

For the site, small home improvements such as decks and porches can use a house location plat, hand drawn on the existing plat, when disturbance is 2,500 square feet or less and the original plat is legible and in its original scale. ^S4

The county's residential comment list shows what reviewers ask when a deck is not detailed. It has separate comments for ledger attachment, ledger bolt spacing, bolt and lag screw edge distance, and deck lateral loads. ^S6

How must a deck ledger be attached in Fairfax County?

The ledger must attach to the house with fasteners from the county's approved list, at the spacing in the handout's Table 6. ^S1 Key points:

• Ledger depth must be at least the depth of the deck joists, and not less than a 2x8. ^S1
• The 2021 VRC also sets a 2x8 minimum, in pressure-treated or approved naturally durable lumber, and says ledgers cannot support concentrated loads from beams or girders or sit on stone or masonry veneer (R507.9.1.1). ^S7
• The existing band board has to be able to carry the deck. If that cannot be verified, the county requires a free-standing deck or an engineered design. ^S1
• Siding comes off before the ledger goes on, and continuous flashing is required at the ledger. ^S1
• Through-bolts are at least 1/2 inch in diameter. Lead anchors are prohibited. ^S1
• Fasteners must be hot-dipped galvanized or stainless steel (R507.9.1.3). ^S7
• Some attachments are prohibited, including at a masonry chimney and at an overhang or bay. In those cases a free-standing or engineered deck is required. ^S1

Show on the plan what the ledger attaches to, the fastener type and size, and the spacing. Those are exactly what the county's comments ask for. ^S6

How deep do deck footings go?

Footings bear on solid ground 24 inches below grade, or deeper if solid ground is not found. ^S1 County inspectors verify bearing before concrete is placed. ^S1 Other footing rules from the handout:

• If a footing edge is closer than 5 feet to an existing exterior house wall, it must bear at the same elevation as the house footings. ^S1
• Footing concrete has a minimum compressive strength of 3,000 PSI. ^S1
• Posts are 6x6, except posts of 2.5 feet or less in height, which may be 4x4. ^S1
• Do not place footings over utility lines. Call Miss Utility at 811 first. ^S1

Footing size comes from the handout's Tables 4 and 5, based on beam influence width and the longest beam span. ^S1 The 2021 VRC requires deck footings to carry imposed loads to the ground (R507.3). ^S7

What does a deck need for lateral support?

Any deck with posts taller than 2.5 feet must be designed to resist lateral load. ^S1 The handout's Table 8 picks the method by post height and deck type. Method 1 uses four tension ties: one at each end joist and two at inside joists. ^S1 Free-standing decks have their own method combinations. ^S1

The 2021 VRC prescriptive lateral connection (R507.9.2) uses hold-down tension devices in at least two locations per deck, within 24 inches of each end. ^S7 Show how lateral load gets to the ground on your plan. The county has a comment for decks that do not. ^S6

What are the guard requirements?

A guard is required when the deck is more than 30 inches above grade at a point 36 inches from the deck edge. ^S1S8 Guard height is at least 36 inches. ^S8

• Openings cannot pass a 4-inch sphere. ^S1S8
• Notching guard posts is prohibited. ^S1
• Guard posts attach with hold-down anchors rated at least 1,800 pounds. ^S1
• Guards cannot be attached to decks framed with 2x6 joists. ^S1
• Guards you do not need must still meet these rules. ^S1

What are the stair requirements?

Stair width is at least 36 inches. ^S1 Treads and risers cannot vary by more than 3/8 inch within a flight. ^S1

What inspections does a deck need?

Fairfax requires three inspections. ^S1

1. Footing: holes are dug and the ledger board is attached. ^S1
2. Framing: posts, beams and joists are installed, before decking. This can be omitted if the bottoms of the joists are more than 48 inches above grade and every framing connection can be seen at final. ^S1
3. Final: all remaining items are installed. ^S1

The approved plat and building plans must be on the job site. ^S1 Inspections can be scheduled in person, by phone at 703-222-0801, online in PLUS, or on the county app. ^S1

FAQ

PlanScan is an invite-only pilot that reads a residential plan set PDF and flags likely issues, such as deck ledger fasteners not shown, with the code section cited. It covers Fairfax County only, its rules are drafts, and it does not replace county review.