Stair Construction&

Layout

Stairwell Opening

*The minimum stairwell opening width is 3 feet.

3'

Tread length & Riser HeightAvoid any variation in tread length or riser height of more than 3/8th of an inch.

Tread length & Riser Height*The UBC states that the minimum tread depth is 9 inches and the maximum riser height is 8 inches

Stringer*A stringer is a usually a 2” x 12” board that is cut to form the risers and treads for the stairs.

*Stringers are made out of hard woods like birch, maple, and oak.

Landings

Landings at the top and bottom of stairs should be at least equal in length to the width of the stairway.

If there is a landing in the middle of the stairs it should also be at least equal in length to the width of the stairway.

Headroom Height

The minimum headroom height on a flight of stairs is 6'-8”.

Riser

A note of DN 14R on your floor plan stairs means: Down 14 Risers.

A note of UP 14R on your floor plan stairs means: Up 14 Risers.

Riser

If you have 13 treads in a stair unit there are 14 risers.

Total LengthTo find the total length of the stairway simply multiply the tread length times the number or runs (treads).

Residential HandrailsThe minimum height of a residential handrail is 34 inches. The maximum height is 38 inches.

Residential GuardrailThe minimum height for a residential guardrail is 36 inches.

Spiral Staircases*Most spiral staircases are made out of steel

Gypsum Board

The UBC states that 5/8 inch type X gypsum board is required for enclosing all usable storage space under the stairs. The IRC states that the gypsum board must be 1/2 inches thick.