When do typical home improvement projects require a building permit?

Short answer

You generally need a building permit for any project that changes your home’s structure, systems, or footprint—think additions, moving or adding walls, new decks, window/door resizing, roofing beyond simple re-shingling, new electrical circuits or service upgrades, plumbing relocations, water heater replacement, HVAC installations, gas lines, pools/spas, and large sheds or fences. Cosmetic work like painting, flooring, cabinets in the same layout, and fixture swaps without moving wiring or pipes often doesn’t require a permit. Always verify with your local building department, as rules vary by city/county.

What typically requires a permit

• Structural changes:
  • Removing or adding walls (especially load-bearing)
  • Adding rooms, bump-outs, dormers, or converting garages/attics/basements to living space
  • Enlarging window/door openings, adding egress windows, cutting foundation openings
  • Decks attached to the house or elevated above grade
• Electrical:
  • New circuits or subpanels, panel upgrades, EV chargers, generators, spa circuits
  • Rewiring, adding outlets in new locations, adding exterior circuits
• Plumbing:
  • Moving or adding fixtures (toilets, sinks, showers), new supply or drain lines
  • Water heater replacement (tank or tankless), repipe projects, sewer line work
• Mechanical (HVAC and gas):
  • New or replacement furnaces, air conditioners, heat pumps, ductwork changes
  • Gas line additions/alterations, fireplaces, venting
• Roofing and exterior:
  • Structural roof work, sheathing replacement, reroof beyond local threshold
  • Siding replacement in some jurisdictions, window/door size changes
• Site and zoning:
  • Sheds above a size limit, fences above a height limit, retaining walls above 4 ft
  • Pools/spas, grading, driveway aprons, work in the right-of-way

Common thresholds (varies by city/county):
- Sheds: 120–200 sq ft max without permit; larger or with electrical need a permit.
- Decks: Permit if above 30 in. from grade or attached to house.
- Fences: Permit if over 6–7 ft high or in front yard zones.
- Retaining walls: Permit if over 4 ft from bottom of footing to top.
- Roofing: Permit if replacing sheathing or >25% of roof area (some areas require for any reroof).
- Windows/doors: Permit if changing size, adding openings, or installing egress.
- Water heater/furnace/AC: Permit for replacement and new installations.
- Electrical: New circuits, service changes, EV chargers, generators require permits.

What usually does not require a permit

• Painting, wallpapering, trim, and similar finishes
• Flooring replacement (carpet, wood, tile) without structural changes
• Cabinet swaps and countertops in the same layout
• Like-for-like light fixture or faucet swaps without moving wiring or pipes
• Minor repairs that don’t affect structure or systems

Tip: Some cities require a permit for window replacements even if same size, or for cabinet work that adds under-cabinet lighting or moves appliances. Always check.

How to check and get a permit (step-by-step)

1. Define scope clearly
   • Write down exactly what’s changing: structure, electrical, plumbing, mechanical, site.
2. Confirm requirements
   • Visit your city/county building department website or call. Ask:
     • Do I need a building/electrical/plumbing/mechanical permit?
     • Are plan drawings required? Engineer/architect stamp?
     • What inspections are needed and in what order?
3. Prepare documents
   • Site plan (for exterior work), floor plan, elevations or sections if structural
   • Product specs (water heater, HVAC, windows, egress wells, deck hardware)
   • Structural details (deck ledger, beam spans, footing sizes)
4. Apply
   • Many jurisdictions offer online submittal. Fees for small projects often range $50–$300; larger remodels $200–$1,000+. Over-the-counter permits may be same day; plan reviews can take 1–3 weeks for small projects and 3–6+ weeks for additions.
5. Post permit and schedule inspections
   • Typical inspections: rough framing, rough electrical/plumbing/mechanical, insulation, final.
6. Close out
   • Keep final inspection approval for your records; you’ll need it for resale and insurance.

Helpful tools and materials for the permit process

• Measuring tools: 25–35 ft tape measure, laser distance meter
• Layout and documentation: graph paper or simple CAD app, scale ruler, pencil, straightedge
• Verification: stud finder, inspection mirror, smartphone for photos
• Specs and labels: model/serial numbers, cut sheets for appliances and fixtures
• Safety gear for site visits: gloves, eye protection, dust mask/respirator when opening walls

Safety considerations

• Unpermitted work can void homeowners insurance and delay home sales.
• Permits trigger inspections that verify life-safety features: GFCI/AFCI protection, proper venting, handrail/guard heights, smoke/CO alarms, egress, and firestopping.
• Electrical and gas work present shock, fire, and explosion hazards. If you’re not fully comfortable, hire a licensed pro.

Tips for best results

• Start with zoning: setbacks, height limits, and HOA rules can override your plan.
• Use current code references (IRC/NEC/IMC/IPC as adopted locally); ask the counter staff which year your jurisdiction uses.
• Provide clear, scaled drawings. Label spans, sizes, and fasteners (e.g., “2×10 DF No.2 @ 16 in. o.c.; (2) 1/2 in. x 4 in. ledger lags @ 12 in. o.c. into rim”).
• Be inspection-ready: expose work, have ladders set, power available, and GFCI tester on hand.
• Keep a permit folder on site with stamped plans and inspection reports.

Common mistakes to avoid

• Starting work before the permit is issued
• Covering rough work (drywall, backfill) before inspection
• Undersized beams/headers and missing deck ledger flashing details
• Incorrect circuit protection (missing GFCI/AFCI) and improper bonding of gas/water lines
• Ignoring manufacturer clearances for water heaters, furnaces, and vent terminations

When to call a professional

• Any structural change (load-bearing walls, headers, beams, foundations). You may need an engineer’s calculations and stamp.
• Service panel upgrades, whole-home rewires, and aluminum-to-copper retrofits
• Gas line installation or relocation, including to ranges, dryers, and fireplaces
• HVAC system design (duct sizing, Manual J/S/D), heat pumps, and multi-zone systems
• Egress window cut-ins through foundation walls, large retaining walls, pools/spas

Cost and time snapshot (typical ranges)

• Water heater permit: $25–$100; 1 day to obtain; 1–2 inspections
• Service panel upgrade permit: $100–$300; 1–3 days to obtain; utility coordination adds time
• Deck permit: $100–$400; plan review 1–2 weeks; 2–3 inspections
• Interior remodel with structural: $300–$1,000+; plan review 2–6 weeks; multiple inspections

If you’re unsure, call your building department with your address and a plain-language description of the work. A 5-minute conversation can save weeks of rework.