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Stairway Width

J

jdieter

Member
Joined
Mar 27, 2014
Messages
4
Location
NW Indiana
First post, glad I found this forum. I'm doing a basement remodel on a 1500sq.ft walkout in NW Indiana, rural location, no building inspections or permits required. Current stairs to basement are 36" wide, we have never used them for moving anything in/out of basement always use the oversize patio door on the walkout end of the basement. I'd like to reduce the stair width to 34" and not sure how that might affect selling the house in the future if my county employs an inspector and follows current codes.
 
The minimum width on stairs is 36" regardless of actual use. Below hand rail can be reduced to the tolerances as described for handrails, but above to 80" must be 36".

Welcome to the forum!
 
You have a couple of options and since this is a walkout basement narrowing the stairs should not be a big concern. The minimum width opening through the floor assembly is 36 inches, However the stair treads above and below the opening can be less as described below. What is the goal? Increase usable floor space in the basement if so a spiral would require the least amount of floor space.

R311.7 Stairways.

R311.7.1 Width.

Stairways shall not be less than 36 inches (914 mm) in clear width at all points above the permitted handrail height and below the required headroom height. Handrails shall not project more than 4.5 inches (114 mm) on either side of the stairway and the minimum clear width of the stairway at and below the handrail height, including treads and landings, shall not be less than 31 1/2 inches (787 mm) where a handrail is installed on one side and 27 inches (698 mm) where handrails are provided on both sides.

Exception: The width of spiral stairways shall be in accordance with Section R311.7.9.1.

R311.7.10.1 Spiral stairways.

Spiral stairways are permitted, provided the minimum clear width at and below the handrail shall be 26 inches (660 mm) with each tread having a 7 1/2-inch (190 mm) minimum tread depth at 12 inches (914 mm) from the narrower edge. All treads shall be identical, and the rise shall be no more than 91/2 inches (241 mm). A minimum headroom of 6 feet 6 inches (1982 mm) shall be provided.
 
mtlogcabin said:
You have a couple of options and since this is a walkout basement narrowing the stairs should not be a big concern. The minimum width opening through the floor assembly is 36 inches, However the stair treads above and below the opening can be less as described below. What is the goal? Increase usable floor space in the basement if so a spiral would require the least amount of floor space.R311.7.1 Width.

Stairways shall not be less than 36 inches (914 mm) in clear width at all points above the permitted handrail height and below the required headroom height. Handrails shall not project more than 4.5 inches (114 mm) on either side of the stairway and the minimum clear width of the stairway at and below the handrail height, including treads and landings, shall not be less than 31 1/2 inches (787 mm) where a handrail is installed on one side and 27 inches (698 mm) where handrails are provided on both sides.

Exception: The width of spiral stairways shall be in accordance with Section R311.7.9.1.

R311.7.10.1 Spiral stairways.

Spiral stairways are permitted, provided the minimum clear width at and below the handrail shall be 26 inches (660 mm) with each tread having a 7 1/2-inch (190 mm) minimum tread depth at 12 inches (914 mm) from the narrower edge. All treads shall be identical, and the rise shall be no more than 91/2 inches (241 mm). A minimum headroom of 6 feet 6 inches (1982 mm) shall be provided.
Click to expand...
R311.7 Stairways.

OK, great that works, thanks for the reply. The kitchen upstairs is on one of the long stairwell walls or I would have considered a spiral.
 
According to Buildingcode.online:

The Ontario Building Code. Stairs. (1) Stairs shall be inclined at an angle of not more than 45° with the horizontal, and their steps shall have risers not more than 210 mm high and treads not less than 220 mm wide exclusive of nosing.

Canadian Building Code Stairs
 
Wider is better than narrow for moving goods from the basement, what do you gain by reducing the width?
 
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