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Building Codes for Decks

Medha Godbole Jan 27, 2019
Thinking of building a deck? It is always advisable to know the building codes before starting the project. Let's get you those in the following sections.
There are certain rules and regulations that have to be followed when building a deck, especially if it is a home construction. A failure to do so may lead to a tryst with the law. Typically, these requirements are universal standards, based on the common materials used for building decks across the globe. Let's see what these rules and regulations are.

Code for Building Decks

There are regulations in place for most everything--from the quality of the pressure-treated wood (if used) to the railing of the deck.

Deck Railings

If the surface of the deck is 30 inches to 5 feet 10 inches above the ground, then a 36 inch railing is a must. On the other hand, if the surface of the deck is 5 feet 10 inches or more above the ground, the railing has to measure 42 inches at the least.
The codes for decks regarding guard rails also say that -
  1. A guard rail should be able to bear a concentrated horizontal load of about 200 lbs along the rail.
  2. Concentrated horizontal load of about 200 lbs over a 1sq ft area on any part of the rail.
  3. A simultaneous vertical load of about 100 lbs and a horizontal load of about 50 lbs across along the rail.


The norms for residential stairs allow the stairs to have narrower treads and be steeper. To begin with, the treads have to be a minimum of 9 and ¼ inch in width. If the treads are used in tandem with stringers, they have to be at least 1 inch thick.

Stringers and Deck Stairways

The deck stairway has to be at least 35 inches between wall faces or a protruding hand rail or even a guardrail. Another issue is the unit rise and unit run--the unit rise and run refers to the entire vertical and horizontal change between each stair tread, but it is not the actual tread size.
The maximum permitted unit rise is 7 ¾ inches and the minimum unit run is 8 ¼ inches. In addition to these, the norms entail that there cannot be any more than 3/8 inch difference between any rises, though they should always be equal.
As far as stringers are concerned, here are some of the main norms.
  1. 1.5" thick (2x material) at least, if there are no supports along its length.
  2. 1" thick minimum when supported along its length.
  3. 3.5" minimum effective depth size (the narrowest part after cutting all the rise and run notches) 9 ¼" width - 2x10 at the most.
  1. Stringers cannot have direct contact with the ground till treated with wood preservative.
Apart from all these, stringers have to be properly secured at the top and bottom and there has to be a maximum of 36 inches space between stringers with open rises, and a 48 inch space to the maximum between the stringers with closed rises.