Stair code width when balusters are used

[massination]

We only have room for exactly 36" wide stair treads. (Building stairs to attic, room we're putting it in is exactly 6 feet wide and we need a 36" walkway beside the stairs). One side of the stairs will be a wall. The other side will be open. If we put a baluster based handrail, obviously the balusters will be set towards the edge of the stair tread. But that technically would make the tread less than 36", since the baluster would be set in a couple inches. But as i understand it, only the area above the handrail needs to be 36" or greater. Is that correct? I think we'd still be code to set the balusters on the 36" wide treads, as long as there is a 31.5" width from the edge of the baluster to the all on the other side of the stairs.
Is this correct? Image below is what I'm picturing, balusters on one side, wall on the other.

 

[Mr. Inspector]

2015 IRC
R311.7 Stairways.
R311.7.1 Width. Stairways shall be not 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 41/2 inches
(114 mm) on either side of the stairway and the clear
width of the stairway at and below the handrail height,
including treads and landings, shall be not less than 311/2
inches (787 mm) where a handrail is installed on one side
and 27 inches (698 mm) where handrails are provided on
both sides.

There was a debate once here if a stairway to an unfinished, not habitable attic or craw space needs to comply with code because most inspectors allow ladders or nothing at all to be used which are not in the code. I don't remember if there was a conclusion about it.

R311.1 Means of egress. Dwellings shall be provided with a
means of egress in accordance with this section. The means
of egress shall provide a continuous and unobstructed path of
vertical and horizontal egress travel from all portions of the
dwelling to the required egress door without requiring travel
through a garage. The required egress door shall open directly
into a public way or to a yard or court that opens to a public
way.

R311.7.12 Ships ladders. Ships ladders shall not be used
as an element of a means of egress. Ships ladders shall be
permitted provided that a required means of egress stairway
or ramp serves the same space at each adjoining level
or where a means of egress is not required. The clear width
at and below the handrails shall be not less than 20 inches.

R311.4 Vertical egress. Egress from habitable levels including
habitable attics and basements not provided with an
egress door in accordance with Section R311.2 shall be by a
ramp in accordance with Section R311.8 or a stairway in
accordance with Section R311.7.

 

[massination]

Thanks for the response. Its still not 100% clear to me, but I think what is described in your first section in bold would mean that what I originally described (36" treads with balusters sitting on the treads) would be up to code, since it would be 36" wide between the area above the headrail and below the headroom height. Its just under the handrail where it would be less than 36" due to the balusters that hold the handrail projecting into the stair treads. By the way, we will be finishing the attic, so we need to make sure these stairs are code compliant.

 

[massination]

Thanks for the response. Its still not 100% clear to me, but I think what is described in your first section in bold would mean that what I originally described (36" treads with balusters sitting on the treads) would be up to code, since it would be 36" wide between the area above the headrail and below the headroom height. Its just under the handrail where it would be less than 36" due to the balusters that hold the handrail projecting into the stair treads. By the way, we will be finishing the attic, so we need to make sure these stairs are code compliant.

Reading it again, it looks like it means the treads must be 31.5 inches wide between the wall and the baluster. I think I'm fine with my plan. I guess the idea of my first post was to get a "yes, what you're planning to do is code compliant" rather than just the code itself. Though having both is great

 

[tbz]

Reading it again, it looks like it means the treads must be 31.5 inches wide between the wall and the baluster. I think I'm fine with my plan. I guess the idea of my first post was to get a "yes, what you're planning to do is code compliant" rather than just the code itself. Though having both is great

The only entity that can truly give you a definitive answer is your local authority having jurisdiction.

The model code allows for the handrails to project inward 4.5" on each side, and when a guard is also serving a duel purpose, both as guard and handrail, the handrail portion of it is allowed to project and reduce the minimum 36-in width, as thus the 31.5-in dimension you note.

However, this is model code, and only your local jurisdiction can confirm if they adopted the model code without modification to this section of the code.

So a definitive yes, is only coming from those that actually have the authority.

We can only concur that the model code allows the reduction as describe and that it is a very common everyday installation done though out new homes.

 

[massination]

excellent, thanks so much. Yes, i agree on making sure the model code hasnt been changed for my county, but in pretty much everything i have experienced so far, they pretty much have not changed anything. So I think I'm going to be good. But we will see.

 

[Genduct]

We only have room for exactly 36" wide stair treads. (Building stairs to attic, room we're putting it in is exactly 6 feet wide and we need a 36" walkway beside the stairs). One side of the stairs will be a wall. The other side will be open. If we put a baluster based handrail, obviously the balusters will be set towards the edge of the stair tread. But that technically would make the tread less than 36", since the baluster would be set in a couple inches. But as i understand it, only the area above the handrail needs to be 36" or greater. Is that correct? I think we'd still be code to set the balusters on the 36" wide treads, as long as there is a 31.5" width from the edge of the baluster to the all on the other side of the stairs.
Is this correct? Image below is what I'm picturing, balusters on one side, wall on the other.

The buildingCode is for NEW Construction! A conversation with your local Code Official should allow you to comeup with an Accomodation whenyou find yourselfwithTechnicaly Infeasiable Consitions and situations like the one you describe