Tag Archives: pole barn stairs

Requirements for Stairs

It Takes a Hole to Raise a Stair

Or at least a hole adequateStair to get the stairs through to the floor above!

I’m a big guy – 6’5” in my bare feet. When stairs have inadequate headroom, my forehead pays the price. When it comes to calculating adequate headroom, most people display their skills of being dimensionally challenged.

The 2012 IBC (International Building Code) is fairly specific when it comes to stairs, and provides a wealth of information:

1009.4 Width.                                        
The width of stairways shall be determined as specified in Section 1005.1, but such width shall not be less than 44 inches (1118 mm).


Stairways serving an occupant load of less than 50 shall have a width of not less than 36 inches (914 mm).

1009.5 Headroom. 
 shall have a minimum headroom clearance of 80 inches (2032 mm) measured vertically from a line connecting the edge of the nosings. Such headroom shall be continuous above the stairway to the point where the line intersects the landing below, one tread depth beyond the bottom riser. The minimum clearance shall be maintained the full width of the stairway and landing.


  1. In Group R-3 occupancies; withindwelling unitsin Group R-2 occupancies; and in Group U occupancies that are accessory to a Group R-3 occupancy or accessory to individual dwelling units in Group R-2 occupancies; where the nosings of treads at the side of a flight extend under the edge of a floor opening through which the stair passes, the floor opening shall be allowed to project horizontally into the required headroom a maximum of 43/4 inches (121 mm).

1009.7.2 Riser height and tread depth. 
Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. The riser height shall be measured vertically between the nosings of adjacent treads. Rectangular tread depths shall be 11 inches (279 mm) minimum measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread’s nosingWinder treads shall have a minimum tread depth of 11 inches (279 mm) between the vertical planes of the foremost projection of adjacent treads at the intersections with the walk line and a minimum tread depth of 10 inches (254 mm) within the clear width of the stair.



  1. In Group R-3 occupancies; within dwelling units in Group R-2 occupancies; and in Group U occupancies that are accessory to a Group R-3 occupancy or accessory to individual dwelling units in Group R-2 occupancies; the maximum riser height shall be 73/4inches (197 mm); the minimum tread depth shall be 10 inches (254 mm).

In general, if one plans around a run of 11 inches and a rise of seven inches, this will get them off to a ‘safe’ start.

To get 80 inches of minimum headroom above the stairs, the thickness of the floor being passed through also has to be accounted for (the floor joists and subfloor sheathing).

With 2×8 joists and ¾” thick sheathing, 88 inches is the magic number. Dividing by the seven inches of maximum rise, it will have 13 risers, which includes the floor at the top. The 12 remaining stairs must travel 132 inches, or 11 feet (this would also hold true for 2×10 joists).

When floor joists go to 2×12, then the length of the hole must be increased to 11’11”. If a beam larger than 17-1/4 inches thick must be passed beneath at the ‘going down’ end of the stair hole, then the hole will need to be longer yet.

A safe rule of thumb for the great majority of cases– allow for a stair hole the width of the stairs plus one inch and a length of 12 feet.

How to Cut Stairs

Stairs – One step at a time…

When I was working for Coeur d’Alene Truss in the 1970’s, I would physically go measure buildings (when requested) to make sure the building being framed, matched the plans which had been provided for the truss takeoff.

How to build stairsOne of my favorite framing crews only asked me out to measure when they were doing a house with stairs – because they had never been taught how to cut stairs and were relying upon me to figure out the stairs for them. I never did actually have to measure any of the houses they were framing…..they always matched the dimensions shown on the plans.

With a bit of foresight, stairs are no longer mysterious.

 Most Common Stair Mistakes:

  1. Not enough headroom (6’8” is minimum above treads).
  2. Rise is too great, or run is too small.
  3. Cutting treads wider than width of stairs ordered.
  4. Failure to set bottom of stair stringers at 4” above grade.

 For Residential (R-3 or inside R-2 occupancy buildings), Residential Accessory Buildings or “U” occupancies, maximum stair rise is 7-3/4” and minimum run is 10”. For all others maximum rise is 7” and minimum run is 11”. Now these requirements are from the International Codes, I have seen some local Building Departments amend these (usually allowing steeper stairs).

 To determine actual rise and tread numbers required, take height from concrete slab top, to second floor sheeting top (in inches) and divide by maximum rise (7.75 in most cases).

 Example: 10’ = 120” vertical distance divided by 7.75” = 15.48. Round result (15.48) up to nearest whole number (16).

This becomes actual tread number which includes floor itself.

Next, to determine actual rise of each tread, divide height (in this example, again 120”) by total tread number. 120” divided by 16 = 7.5 (or 7-1/2”).

 Use a framing square to lay out cutting on one of (3) three 2×12 stair stringers (stairs 48” and wider require four stringers).

Cutting Stairs

Use a circular saw to cut 2×12 as far as rise and run line intersections. Use a hand saw to finish cut. After first stringer is cut, use as a pattern for the other two. Cut a 2×6 as a strongback to reinforce each 2×12 stair stringer.

cutting stairs

Nail one 2×6 to each 2×12 stringer with staggered 10d commons approximately 6 inches o.c.. Important, nail the 2x6s on left side of (2) two stringers and right side of the other.

Install two stringers in stairway hole with 2×6 strongback reinforcements toward the stair outsides (against walls, if any). This will make outside-to-outside 2×12 stringer measure 3” less than the stairway opening width. Center third stringer between other two.

 Cut 2×6 treads (two per step) to a length 1” less than stairway width (36” for 3’ wide stairs).

cutting stair treads

 Install on stringers with each end of treads 1” past outer stringers.

 Overhang treads past step below by 1”.

 In the case of an 11” minimum tread requirement, treads will overhang ¾” and place a 3/8” space between the two 2×6 treads, as well as between the rear tread and the stringer.

cutting stairs

Rip 2×4 lengthwise to form 2×2. Cut the 2×2’s to fit tight left-to-right between the vertical faces of the stringers. Place 2×2 so it is no more than 4” above or below a stair tread. Nail through stringer into each end of 2×2 with two 10d nails.  

Cutting Stairs

All stairs which go to within four inches of grade (whether sitting on top of a concrete slab or not) must be isolated from ground by placement of two pieces of pressure treated 2×12 below the bottom. These may be embedded into a concrete slab or pad.

 Top of stair stringers will attach to either landings or next floor framing by use of a Simpson LSCZ bracket

Cutting Stairs

 Following these simple steps (pun intended) will have you and your friends walking up and down your new stairs in nearly no time at all!