August 1998 Edition

Deck Stairs

We have a deck that is around three feet above the ground. We would like to install a set of stairs but do not know what the requirements are. Would you help us out?                       
We continually see professional deck stairs that are not properly constructed. There are some simple basics to remember when constructing stairs.  Most decks are made from cedar or pressure treated wood to withstand the weather.
First, be sure to begin with proper support. All stairs should be supported on a concrete pad. The wood stair stringers are not allowed to be in contact with the ground. The wood is rated for above ground use only.
Second, make sure the top of the stairs has full bearing against the deck. The top step should be flush with the top of the deck. Stairs that are lowered one step do not have sufficient bearing at the top and could split with the grain of the wood.  This could result in an accident.  You may need to raise  the  concrete landing  as  needed for the height to work out.

Stair1

The stairs should be 36” wide. It is recommended that you use three stringers. One on each side and one in the middle. If the length of the stairs is over eight feet long, you will need to install a support in the center of the span to keep the stairs from bouncing and to add       proper support. The stair stringers should be cut out of 2x12 stock for maximum support. Some building centers have “prefabricated” stringers already cut out with the proper treads and risers. Just cut to length.
If you are making your own stairs, keep two important dimensions in mind. The depth of the step is called a “tread”. Treads must be a minimum of 9” wide. Treads any less than 9” could be a trip hazard. Your foot might not have enough surface to stand on and the foot could slip. Treads are typically constructed out of 2x or 5/4 material. Just match what is used for the top of the deck. The height is called a “riser”.  Risers over 7 3/4” are considered too high and could be a trip hazard especially for small children. All of the treads must be the same depth and all of the risers must be the same height. The building code does not allow either to vary more than 3/8”. The distance the step overhangs at the edge is called a “nosing”. The maximum allowable overhang is 1 1/4”.  If the step overhangs more than this, it increases the chances for the board to split when stepped upon.

Stair2

Since your deck is over 30” above the ground, you will need to add a handrail to the stairs and a guardrail to the deck. The stair handrail must not be less than 34” high nor more than 38” high measured vertically from the nosing of the tread. The deck guardrail must not be less than 36” high. All rails must have intermediate rails or ornamental closures which do not allow passage of an object 4” or more in diameter. In other words a 4” ball should not fit through any part of the rail. The triangular opening formed by the riser, tread and bottom rail of the handrail at the open side of a stair must be small enough to restrict the passage of a 6” ball.
l It is recommended that the top of the handrail be designed to accommodate a grip. In other words, some of the rails are 2x6 caps and cannot be gripped if you accidentally slip and start to fall down the stairs. All handrails should be small enough for the hand to grab.
Stair3
The building code states the handrail should have a circular cross section of 1 1/4” to 2” or a noncircular cross section with a perimeter dimension of at least 4” but not exceeding 6 1/4”. This is normally not enforced on deck guardrails and handrails. Custom prefabricated handrails are available from building material dealers. The rails are pressure treated and can be painted if desired. 
By following some simple rules, you can be assured your stairs will be comfortable to use and will be safe.

If you have a question, change of address, comment, home tip or would like to send Home Tips to your clients, send your letter to Home Tips, Christian Building Inspectors, Inc., 3697 Habersham Lane, Duluth, Georgia 30096. You can E-Mail your questions to us at rodharrison@christianbuildinginspectors.com. We reserve the right to edit questions for length.


Quote Of The Month

“Accept the challenges, so that you may feel the exhilaration of victory.”
- General George S. Patton
 

A Tip Of The Hat To:

Diana Coombs

Century 21/Richard Williams

2000 Riverside Parkway

Lawrenceville, Georgia 30043