Does my deck require a permit?

Almost certainly yes if the deck is attached to your house. Attached decks require permits in virtually every US jurisdiction — the attachment to the house creates a structural connection that affects the home's structural integrity and requires engineering review. Freestanding decks (not attached to the house) may be exempt if they are close to grade (typically under 18–30 inches above grade depending on jurisdiction) and under a certain square footage (commonly under 200 square feet). Check with your local building department before assuming an exemption applies.

What happens if I build a deck without a permit?

Building without a permit creates several problems: (1) Safety — unpermitted decks are a leading cause of deck collapses, as the most common failure modes (ledger attachment, footing depth) are exactly what permits catch; (2) Resale — unpermitted structures must typically be disclosed and may reduce buyer pool; (3) Insurance — a structural failure on an unpermitted deck may not be covered by homeowner's insurance; (4) Retroactive permitting — some jurisdictions require demolition if a structure can't be retroactively inspected; others allow inspection with partial deconstruction. The permit costs $150–$600 for most residential decks — it is not a meaningful cost relative to the project.

What does a deck permit inspection check?

Deck inspections focus on the two most common failure points: (1) Footing depth — footings must extend below the frost line to prevent heave (frost line depth varies from 28 inches in Nashville to 48+ inches in Chicago); (2) Ledger attachment — improper ledger attachment to the house is the #1 cause of deck collapses. Inspectors also verify joist sizing for the span, guardrail height and balustring spacing, and stair geometry (rise/run ratios). Some jurisdictions require both a footing inspection and a framing inspection before decking is installed.

How long does a deck permit take to get approved?

For a standard residential deck, most Midwest municipalities approve permits within 1–3 weeks of a complete application. Permit applications require drawings showing the deck's dimensions, attachment method, footing locations, framing layout, and elevation (height above grade). The faster applications come in with complete drawings — incomplete applications restart the review clock. In Chicago, where the permitting process is more involved, expect 3–6 weeks for a standard deck permit.

Deck Permit Requirements in the Midwest: What's Required in KC, Chicago, Columbus, and More

Deck permitting requirements catch homeowners off guard more than almost any other project — the assumption that a relatively simple outdoor structure doesn't need permits leads to significant problems at resale and, more importantly, genuine safety risks. Here's what's required and why it matters.

The Core Safety Issue: Why Permits Catch What You'd Miss

Two failure modes cause nearly all deck collapses in the US, and both are precisely what permit inspections verify:

1. Improper Ledger Attachment

The ledger is the horizontal board that connects your deck to the house's rim joist. It is the most structurally critical element of an attached deck — and the most commonly done wrong.

Common defects that go undetected without inspection:

Ledger attached through house siding (moisture trap that causes rot and structural failure)
Inadequate fastener pattern (type, size, and spacing of lag bolts is specified by code for the load)
Missing or improper flashing (water penetrates between ledger and house, rots the rim joist)
Ledger attached to unsound structure (attaching to a deteriorated rim joist transfers nothing)

A ledger that fails doesn't give warning — it fails suddenly under load.

2. Footing Depth

Deck posts bear on concrete footings that must extend below the frost line to prevent heave. Frost heave is a seasonal cycle where saturated soil expands when frozen, pushing footings upward. A footing that heaves in winter and settles in spring works the post connections loose, tilts the deck, and eventually causes structural failure.

Frost line depths by Midwest metro:

Metro	Required Footing Depth
Chicago, IL	42–48 inches
Kansas City, MO	30–36 inches
Columbus, OH	30–36 inches
Cincinnati, OH	24–30 inches
St. Louis, MO	24–30 inches
Nashville, TN	12–18 inches

A deck footing poured at 12 inches in Chicago will heave — without exception. The inspection catches this before concrete is poured.

Permit Requirements by Midwest Metro

Kansas City, MO

Attached decks: permit required, no exceptions
Freestanding decks: permit required if over 30 inches above grade or over 200 sq ft
Required drawings: site plan with setbacks, framing plan, footing detail, elevation
Typical fee: $150–$350 for a residential deck
Approval time: 2–4 weeks

St. Louis, MO (City and County)

Permit required for all attached and elevated decks
St. Louis County: online permit portal available; simpler for standard decks
St. Louis City: more involved process; plan review through Building Division
Typical fee: $200–$500
Approval time: 3–5 weeks

Chicago, IL

Permit required for all attached decks and all decks over 10 inches above grade
Chicago requires licensed contractors for most deck construction (homeowner-builder permits have limitations)
Historic district properties face additional review
Typical fee: $300–$750
Approval time: 3–6 weeks

Columbus, OH

Permit required for all attached decks and freestanding decks over 30 inches or 200 sq ft
Columbus is generally considered one of the more efficient Midwest permitting offices
Online permit portal available for straightforward residential projects
Typical fee: $175–$400
Approval time: 2–3 weeks

Cincinnati, OH

Permit required for all attached decks
Freestanding decks under 30 inches and 200 sq ft may be exempt
Hamilton County and individual municipalities have separate permit offices — know which jurisdiction your property is in
Typical fee: $150–$350
Approval time: 2–4 weeks

Nashville, TN

Permit required for all attached decks
Freestanding decks: permit required if over 12 inches above grade
Nashville's Building Codes Division handles residential decks; permit portal available
Typical fee: $200–$500
Approval time: 3–5 weeks

What Goes Into a Deck Permit Application

Your contractor should prepare and submit a complete package:

Document	What It Shows
Site plan	Property lines, setbacks, deck location on lot
Framing plan	Joist sizes, spacing, spans; beam sizes; post locations
Ledger detail	Attachment method, fastener pattern, flashing approach
Footing detail	Diameter, depth, type (poured concrete, tube form, helical pier)
Elevation drawing	Height above grade, guardrail height, stair configuration

Applications submitted without all required documents are returned for completion, restarting the review clock. A complete, well-documented application is the single most effective way to get fast approval.

Freestanding Deck Exemptions: Read Carefully

Most Midwest jurisdictions have some exemption threshold for small freestanding ground-level decks. The conditions are typically AND (not OR):

Must be freestanding (not attached to the house at all)
Must be below a height threshold (typically 18–30 inches above grade at all points)
Must be under a square footage threshold (typically 200 sq ft)
Must not provide roof or egress access

All three or four conditions must be met simultaneously. A deck that is freestanding and small but is 32 inches above grade still requires a permit. A deck that is close to grade but attached to the house still requires a permit.

When in doubt, call the building department. They will tell you quickly whether your project needs a permit, and the call establishes a documented record of the guidance you received.