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Loft stairs question of code

chapmgre's picture

My situation is this.


I have a smallish log home in the mountains.  There is a circular staircase that i assume meets code to the second floor.  The circular staircase eats up quite a large chunk of the downstairs living room. (poor disign)  My tow questions are:


1.  If I move the circular stair case to the outside and put a deck off the loft would that make the space compliant.

2.  Then I would build a steep or alternating stair case near the wall from the interior side.  Rise is 9 feet run is 8 feet


Would this meet code since there was one coded staircase? 




The outside steps certainly (post #207304, reply #1 of 8)

The outside steps certainly addresses the egress problem and that might be the most serious sticking point in this project..

In fact the stair requirements are in the egress section of the code. 

This is what it says (ICC residential code)

R311.7.4.1 Riser height.
The maximum riser height shall be 73/4 inches (196 mm). The riser shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).


R311.7.4.2 Tread depth. The (post #207304, reply #2 of 8)

R311.7.4.2 Tread depth.
The minimum tread depth shall be 10 inches (254 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread’s leading edge. The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). Consistently shaped winders at the walkline shall be allowed within the same flight of stairs as rectangular treads and do not have to be within 3/8 inch (9.5 mm) of the rectangular tread depth.


Just to clarify (post #207304, reply #4 of 8)

What you are saying the code says is that if a tread meats the minimum 10 inch requirement the actual tread (ie the wood) would be wider by the amount of tread overhang?  Right?

Basically the 10 inche minimum is the nose to nose measurement, not nose to riser measurement? 


 Yes I read it nose to nose. (post #207304, reply #6 of 8)

 Yes I read it nose to nose.


Here's a link to a "visual guide" to the 2006 Code. I'm not (post #207304, reply #8 of 8)

what's changed in the more recent versions, but the pictures may make it a bit easier to discuss.

Talk to your local building (post #207304, reply #3 of 8)

Talk to your local building inspector to see how he would interpret the code section on tread depth--it could be that he would consider an alternating step stair as meeting the requirement that the tread depth measurement for adjacent treads would be met if you define the "adjacent tread" as the tread directly above--in other words, none of  the left-side treads or right-side treads have an intervening, unused tread for that foot.

My local building official approved just such a stair for access to my wine cellar, which needed a 7-foot rise in 4 feet of run. The stair is very comfortable in use--even my 85-year-old mother uses it with ease. It has handrails on each side, which make it feel even more secure. All the treads are 11" deep, and the risers are 7-1/2".

Ladder? (post #207304, reply #5 of 8)

I don't know if ladders for such applications are code compliant.  Perhaos someone knows and will be willing to share.

I able to climb and depending on the use of the loft, I think a ladder is pretty cool for a cabin.  Kids love it.


I think if he has a direct (post #207304, reply #7 of 8)

I think if he has a direct egress to a deck with compliant stairs he can use a ladder inside.

Most of these things are really in the eye of the local fire and building officials so we are just looking at the code and guessing what they might decide. These are usually tombstone decisions. If they had people trapped in a fire locally, they may go far beyond the IRC.