Fairfax County Deck, Addition, and Basement Permit Guide

Fairfax County treats residential decks, finished basements, renovations, and additions as addition/alteration records for eligible one- and two-family dwellings and townhouses.

Permit takeaway

Residential additions and alterations include renovations, decks, finished basements, and more, and are submitted online in PLUS under the Building tab.

Zoning and placement

Land disturbance can trigger an associated grading plan, so outdoor additions and decks should be checked for grading requirements before submission.

Building and trade review

Fairfax County separates work types such as additional square footage, interior alterations, and combined exterior-interior alterations during the application process.

Call before applying when

Call before applying if the project adds square footage, includes a deck or screened porch, changes structure, finishes a basement, or may disturb enough land to need grading review.

Documents to prepare

• PLUS application
• Project drawings
• Deck or addition dimensions
• Grading information when applicable
• Structural details for altered areas

Inspection planning

• Submit the addition/alteration record
• Upload plans
• Resolve plan review comments
• Download permit card and approved plans
• Schedule inspections at required construction stages

Official sources

• Fairfax County Addition/Alteration Residential
• Fairfax County Residential Building Permit Library
• Fairfax County Site Plans Permit Library

This guide is a planning summary. Always verify the current requirements with the local office before starting work.