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Decks

Code Reference: 2018 International Residential One and Two Family Dwellings Code >> Section R507 Exterior Decks

Ground Level Floating Decks and Patios


A permit is "not" required if:

  • The proposed deck is not permanently attached to your home or any structure by way of band boards.
  • The proposed deck is no greater than thirty inches (30") from the top of the deck's walking surface to the top of the finished grade below at any point around the perimeter of the deck. (Requiring Guard Rails)
Applicable Info:

How to Build a Floating Wood Patio Deck


Above Ground Decks Attached to a Structure


Thirty inches (30") or greater from the top of the deck's walking surface to the top of the finished grade below.

A permit is required!

Applicable Info:

“The Prescriptive Residential Wood Deck Construction Guide is fantastic. If you build decks or are planning to build a deck, or just want some great info on how to properly build a deck.”

Download this free guide from the American Wood Council:

Design for Code Acceptance (DCA) 6 - Prescriptive Residential Wood Deck Construction Guide - 2015 IRC Version

Includes guidance on provisions of the 2015 International Residential Code (IRC) pertaining to single level residential wood deck construction. Provisions contained in this document that are not included in the IRC are considered good practice recommendations. Includes Commentary and Appendices.

Free Standing Decks Greater than 30" Above Finished Grade

A permit is required!

Decks which are free-standing do not utilize the exterior wall of the existing house to support vertical loads (see Figure 21 below); instead, an additional beam with posts is provided at or within L/4 of the existing house.

  • If the deck is abutting the house, the associated deck post footings shall be placed at the same elevation as the existing house footing.
  • If the deck is away from the house, the associated deck post footings shall be a minimum of twenty-four (24") in depth and twelve inches (12") in diameter and the deck posts shall be permanently attached to the post footings by way of approved fasteners and post-bases to prevent uplift and to withstand lateral forces. 


Figure 21
Figure 21 Free-Standing Deck

Deck Stability

Decks greater than 2 feet above grade shall be provided with diagonal bracing.

Diagonal Bracing: Provide diagonal bracing both parallel and perpendicular to the beam at each post as shown in Figure 22. When parallel to the beam, the bracing shall be bolted to the post at one end and beam at the other. When perpendicular to the beam, the bracing shall be bolted to the post at one end and a joist or blocking between joists at the other. When a joist does not align with the bracing location, provide blocking between the next adjacent joists. Decks attached to the house do not require diagonal bracing perpendicular to the house.

Figure 22

Figure 22 Diagonal Bracing Requirements

All other regulations in regards to Free Standing Decks shall meet or exceed the requirements set forth above within the Design for Code Acceptance (DCA) 6 - Prescriptive Residential Wood Deck Construction Guide - 2015 IRC Version.

For questions or comments, please contact the Code Official: Jeremy Crowe @ 636-629-0333 ext. 200 or email: cityinspector@stclairmo.us


CITY OF ST CLAIR 
#1 PAUL PARKS DRIVE
ST. CLAIR, MO 63077
Ph: 636-629-0333
Fax: 636-629-6467
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