Missouri · State Deck Permit Guide

Missouri Deck Permit Requirements (2025)

Updated January 2025Code: Varies by jurisdiction
⚠ Missouri Quick Answer

Missouri has no mandatory statewide residential building code. St. Louis County, Jackson County (Kansas City), and major cities have adopted and enforce the IRC. Many rural Missouri counties have limited or no residential building permit requirements. Verify with your specific county or municipality.

Building Code Framework in Missouri

Missouri uses the Varies by jurisdiction as its residential building code foundation. This sets the structural baseline for deck construction — ledger attachment, framing, footings, and railing requirements. Local counties and cities may adopt amendments.

Permit strictness level for Missouri: Standard (varies). Always confirm the specific threshold with your local building department before starting any deck project.

When Is a Permit Required?

In most Missouri jurisdictions, a building permit is required for: any deck attached to the house via a ledger board; any deck elevated 30 inches or more above grade; freestanding decks exceeding the local size threshold (commonly 200 sq ft); and any deck with a permanent overhead cover (pergola or roof).

Ground-level freestanding decks under the local size threshold may be exempt in some Missouri jurisdictions — but this must be confirmed locally, as exemptions are not universal.

Key Technical Requirements

Frost depth: 24–30 inches. Footings must extend below this depth to prevent frost heave.

Railing requirement: Decks 30 inches or more above grade require guardrails with a minimum 36-inch height. Baluster spacing must prevent a 4-inch sphere from passing through.

Ledger attachment: Attached decks must use lag bolts per IRC Table R507.9.1.3(1) with proper flashing to prevent water infiltration — the leading cause of structural deck failures.

Pressure-treated lumber: All lumber in contact with concrete or soil requires ground-contact-rated treatment (UC4A minimum). Above-grade lumber must be UC3B rated minimum or naturally decay-resistant species.

Permit Application Process in Missouri

Permits in Missouri are issued by local city or county building departments — not a state agency. To apply:

  1. Prepare your four drawings: site plan, framing plan, elevation, and footing detail
  2. Find your local building department's permit portal (search your city/county name + "building permits")
  3. Submit online or in person and pay the permit fee
  4. Wait for plan review — typically 5–15 business days for residential decks
  5. Post the approved permit at the construction site
  6. Schedule and pass inspections: footing, framing, and final

Download our free Deck Permit Application Checklist to prepare your drawings and inspections.

Frequently Asked Questions — Missouri Deck Permits

Who issues deck permits in Missouri?+
Deck permits in Missouri are issued by your local city or county building department, not a state agency. Search for your city or county name plus "building permits" to find the right contact. If you live outside city limits in an unincorporated area, contact your county building department directly.
Can I apply for my own deck permit in Missouri without a contractor?+
Yes. Most Missouri jurisdictions allow homeowners to apply as owner-builders for permits on their primary residence. You'll need to prepare the required drawings and pass the same inspections a contractor would. Check with your specific building department for any owner-builder restrictions that may apply locally.
How much does a deck permit cost in Missouri?+
Permit fees in Missouri vary by jurisdiction. Most use a valuation-based formula (typically 1–5% of construction value) or a flat fee. For a typical residential deck valued at ,000–missouri5,000, expect permit fees in the range of missouri00–24–30 inches00. See our permit costs guide for state-by-state fee comparison data.
Related: Do I need a permit? · Draw deck plans · Permit costs · Permit checker