42 inch stair width?

[mtlogcabin]

I have a proposed remodel. Existing stair serving the 1st and 2nd floor.

Architect would like to extend that stair into the basement to serve as the second exit from the basement. Great, However the basement foundation is 2 feet thick and in order to line up with the existing stairs it would be finnished at 42.5 inches. 1.5 inches less the than the 44 inches required. The stair will be serving an OL of about 62.

Any historical knowledge as to where the 44" requirement came from?

Any suggestions on how to allow this new portion to be less than the required minimum?

Does 101 allow less than 44" on an exit stair?

The building was constructed in the 20's of 2ft thick brick walls and heavy timber. It will be primarily office space with a couple of small M occupancies on the main floor. 6,000 sq ft per floor, building will be sprinklered over time as tenants occupy spaces.

 

[brudgers]

My understanding is that the 44" dimension is intended to allow for a fully equipped firefighter to pass a person descending...or ascending as the case may be.

Personally, I suspect that alignment is being led by aesthetics and ease, not technical infeasibility.

 

[Coug Dad]

Back when the code specified egress with in 22 inch units a 44 inch stair was two units. Is the building sprinkered? Is it required to be sprinklered? Have them perform a NFPA 101A analysis for new construction and see if it passes with points taken away for egress.

 

[Big Mac]

Is the occupant load less than 50?

 

[fatboy]

"Personally, I suspect that alignment is being led by aesthetics and ease, not technical infeasibility."

Not seeing the application, I would tend to agree. However, I would also not rule it out of consideration. More curiosity than anything, what is the occupancy group?

OP said occupant load was 62.

 

[FM William Burns]

Might be similar to Big Mac's reply but 101 will give you:

7.2.2.2.1.2 Minimum New Stair Width.

(A) Where the total occupant load of all stories served by the stair is fewer than 50, the minimum width clear of all obstructions, except projections not more than 4 1/2 in. (114 mm) at or below handrail height on each side, shall be 36 in. (915 mm).

"About 62" might just have to be 49 ?

 

[mtlogcabin]

Personally, I suspect that alignment is being led by aesthetics and ease, not technical infeasibility

I went and looked at it and yes it is driven by aesthetics and wanting insulation and a smooth surface to cover the rough rumble rock foundation that may attribute to scraped knuckles by those using the handrail on the stairs.

 

[Big Mac]

Sorry I missed the note about 62 occupants. Chapter 34 doesn't appear to grant much relief either. The only relief there is for existing stairways, not new ones. 44" it is.

 

[north star]

= =

44" or 49 occs.

+ +

 

[brudgers]

I went and looked at it and yes it is driven by aesthetics and wanting insulation and a smooth surface to cover the rough rumble rock foundation that may attribute to scraped knuckles by those using the handrail on the stairs.

Right. Any hardship is self imposed.

The architect needs to put on their design undies.

 

[peach]

Is the basement already occupied? If so and the architect is trying to make things safer in an existing building - that's where a modification may be justified.

 

[TheCommish]

it seem to me this an example of the need to seek and grant a varance though the appels process

 

[mtlogcabin]

The basement is currently non occupied but will be remodeled for office use. The real problem after meeting with the Architect again is not the width of the stair itself it is where it will penetrate the floor going the existing stair enclosure and the location of the existing wall supporting the existing stair. That will be 42.5 inches at that point coming through the floor unless the existing stair is rebuilt.

 

[rooster]

Does the stair serve 62 occupants or 31 occupants?

 

[mtlogcabin]

31 occupants

 

[Big Mac]

If one stair is blocked for any reason, it serves 62.

 

[Yankee]

Add another exit somewhere?

 

[rooster]

31 occupants

I guess I was looking at IBC 1009.1 ex.1 where it says "Stairways serving an occupant load less than 50..."

But I see by Burns's post, 101 says the total occupant load.

To Big Mac:

I was looking at IBC 1005 Egress Width which states that when one means of egress component is lost the required capacity shall not be reduced to less than half. So according to the IBC you could potentially half an egress component that does not meet the width to serve the entire floor.

 

[Big Mac]

Rooster, just before the sentence you cite in Section 1005, it says "The width shall be not less than specified elsewhere in this code"

Since specific requirements overn over general requirements' Section 102.1. Would the requirements specific to stairways in Section 1009 take precedence over the general statement contained in Section 1005.