See here if you are interested in stairway code for interiors.
Q: Why Does Building Code Matter for Decks?
In short, because deck failures result in more injuries and deaths than any other parts of the house.Homeowners may conveniently ignore building code in other parts of their home, but decks are not one area where I would recommend this. Decks get plenty of wear and tear. Decks have lots of people on them at once. Deck rails have people leaning against them. Deck get the brunt of abuse from weather: snow, rain, and sun. In other words, they need to be solidly built.
It is estimated that older decks have a life expectancy of only 10-15 years. Times change, codes change. For example, your deck may have toe-nailed connections. If so, be advised that toe-nailing is no longer an accepted connection, per current IBC (though older decks may be grandfathered in).
Q: What's the Difference Between Railing and Guards?
It's just a difference in terminology. Railing protects stairs; it runs on the incline up and down the stairs. A guard runs horizontally along a landing or other flat area with a drop on the other side.Q: How High Does the Deck Have to Be to Require Guards?
30 inches above grade. Grade refers to the ground level directly adjoining the deck.Q: Can I Construct Any Kind of Guard on Decks Lower Than 36" High?
Yes and no. If you decide to construct a guard on a deck low enough that it doesn't require guards, it's up to you as to guard rail height and baluster spacing. However, these guards still must be as strong as guards located higher on decks. It is understood that people will lean against guards, and code requires that these guards not collapse, even though only minor injuries would result.Q: Can a Bench on the Deck Serve as a Guard?
No. Many homeowners are concerned about preserving the view from their decks, and they wonder if benches are acceptable substitutes for deck guards; they are not. Guards must be installed behind benches, though they do not have to be higher than other guards on the deck.Q: Do Deck Guards Need Balusters?
Yes. Balusters are vertical posts that prevent people (particularly children) from falling off the deck under the railing.Alternatively, you can install in-fill guards. These are horizontal guards that parallel the topmost guard.
Q: How Far Apart Do Balusters Need to Be?
Four (4) inches or less.Q: For the Stairs, What is the Minimum Tread and Maximum Rise?
Tread is the flat part that you place your foot on. Rise is the vertical distance from one stair to another.Treads must be at least 10 inches, measuring from front to back. The rise can be no more than 7.25" high.
Q: How Stong Must the Guard Rails and Balusters/Rail Infill Be?
IBC states that, at a bare minimum, guards must be able to sustain a 200 lb. force. In other words, imagine a strong man pushing horizontally against the railing. The railing has to sustain 200 pounds of force.However, it is important to note that, from a testing standpoint, the guardrail must sustain 2.5x the minimum force. So, really the guardrail must be able to sustain 500 pounds of force.
Balusters and in-fill rails must sustain a minimum of 50 pounds, or a minimum testing force of 125 pounds.
Short story: 500 pounds for guardrails, 125 pounds for balusters/infill rails.