The procedure for building stairwells varies from one locality to another due to differences in the building code.
Rough framing of stairs is normally done during the framing of the building. Regardless of the procedure, the rough opening in the floor, in combination with the height from the floor level, will decide the length and the width of a stairway.
With regard to building codes, keep the following things in mind:
• Check the local building codes for special requirements in your area.
• The code requirements for residential construction may vary from requirements for commercial ones.
Stair Framing Requirements - Headroom
Headroom is defined as the closest vertical distance between any stair tread nosing and any structure or ceiling above the stair.
Standard headroom clearance is 6 feet 6 inches for residential stairs, and 6 feet 8 inches for commercial stairs. However, 7 feet (if at all possible) is desirable.
Stair Framing Requirements - Stringers
All stringers should be constructed in accordance with the local building codes.
The size of the stringer material will be found in the construction drawings. All materials used for stringers should be selected at one time and the crowns should be matched. Normally cut-out center stringers are required on wooden stairways wider than 30”.
Stair Framing Requirements – Treads and Risers
For optimum safety and comfort, it is important that the dimension of a stair tread and riser be uniform within any stairway.
As a person walks down a flight of stairs, their stride is uniform. Therefore, the system to support the person (the riser and treads) should also be uniform.
A tread and/or riser constructed of a different size than the others will create an unsafe condition and will most likely cause the person to lose his/her balance and fall.
Stair Framing - Width Requirements
The minimum width required is also specified in the building codes.
The standard is a minimum stair width of 36” to 44” depending on the type and occupancy of the building.
Stair Framing Requirements - Handrail
A handrail -- a continuous rail for support along the side -- is used on stairways to assist people when ascending or descending a stairway.
It differs from a guardrail, which is a railing that is erected on the exposed sides and the ends of stairs and platforms. A guardrail incorporates a handrail.
Open stairways have a low partition or banister. The handrail in a closed stairway is called a wall rail because it is attached to the wall with special brackets.
As a rule standard stairwells have a rail only on one side. However, stairs wider than 44” usually require a handrail on both the sides.
Always refer to the local codes for specific requirement.
Stair Framing Requirements - Stairwells
Stairwells must be constructed so that they are wide enough and long enough to provide the code-required width and headroom clearance for the stair below them.
If the architectural drawings do not specifically detail the stairs, a carpenter can be confronted with tough situations at the job site.