basement stairs

15 years ago

hi I need help with basement stair code questions. I am replacing a basement stairway in the Kalamazoo, Michigan area that has 2 x 10 treads that require a 8-1/4 tread cut. Will I be required to enlarge the cut to 9 inches and use 2 x 12 to meet code or will a 8-1/4 cut with 2 x 10 suffice for basement stairs?

I need to make a winder due to room size constrictions. Do the three winders need to have 6 inches at the narrow end or can they come to a point as long as I have 9 inches at a 12 inch travel point from the inside?

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Comments (3)

joed
15 years ago
This link might be usefull.
manhattan42
15 years ago
From a Code point of view:

Michigan currently uses the 2003 International Residential Code if I understand correctly.

Under the 2003 IRC, MAXIMUM riser height for any stair is 8 1/4"...

MINIMUM tread depth is 9"...

Winders require a MINIMUM tread depth of 6" at any point.

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From a carpentry point of view:

NO ONE uses anything less that 2x12s for stair stringers under any circumstance.
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mightyanvil
15 years ago
The 2003 IRC limits stair risers to a maximum of 7 3/4" and treads must be a minimum of 10".

Winder treads must be a minimum of 6" at any point but also a minimum of 10" at a point 12" from the narrow side.

The size of the stringers depends on how far they span and if they are supported against walls.