Stairs by floor height · 11 ft 6 in · Straight
Straight stairs for an 11 ft 6 in floor height
20 risers of 6 7/8″ and 19 treads 11″ deep, at 32°. 36″ wide, it takes 3′ × 17′ 5 7/16″ of floor. It is 17′ 5 7/16″ long and needs an opening of 11′ 6 3/8″ in the floor above for 2 m clear over every nosing.
Open this stair in uCADWhat it’s made of
More or fewer steps
11 ft 6 in (138″) can be climbed in fewer, higher steps or more, lower ones. Each opens in uCAD as this stair with that many risers.
| Risers | Each riser | Going | Pitch | Run of a straight flight | How it walks | In uCAD |
|---|---|---|---|---|---|---|
| 18 | 7 11/16″ | 9 13/16″ | 38° | 13′ 11 5/16″ | treads under the IRC’s 10″ | open |
| 19 | 7 1/4″ | 10 1/4″ | 35° | 15′ 4 1/4″ | comfortable | open |
| 20 | 6 7/8″ | 11″ | 32° | 17′ 5 7/16″ | comfortable (drawn here) | open |
| 21 | 6 9/16″ | 11 13/16″ | 29° | 19′ 8 1/4″ | comfortable | open |
The IRC (US homes) allows risers up to 7¾″ and asks for treads of at least 10″, 6′8″ of headroom and a width of 36″; states and towns amend it. Check the code that applies to yours.
What it’s made of
Drawn as it’s built, in timber with open treads: treads housed in the stringers, posts under the turns, a railing on its newels. 362 parts in all, every bolt and weld among them. Sizes in inches, length × width × thickness.
| Part | Qty | Length | Width | Thickness |
|---|---|---|---|---|
| stringer (shaped) | 2 | 244 3/4″ | 10 3/8″ | 1 15/16″ |
| handrail, round 50 mm (shaped) | 2 | 240 9/16″ | 1 15/16″ | 1 15/16″ |
| tread | 17 | 37 3/16″ | 12″ | 1 9/16″ |
| tread (shaped) | 2 | 37 3/16″ | 12″ | 1 9/16″ |
| post, timber 90x90 | 2 | 54″ | 3 9/16″ | 3 9/16″ |
| post, timber 90x90 | 2 | 46 7/8″ | 3 9/16″ | 3 9/16″ |
| baluster, steel square bar 18 mm (shaped) | 80 | 33 3/8″ | 11/16″ | 11/16″ |
Fixings: 5 × tie rod M10x1041, 34 × washer M10, 26 × nut M10, 80 × stud M8x80, glued, 80 × screw 5x45, 2 × bracket, concealed post base 90, 4 × anchor bolt M10x100, 4 × stud M10x117, 4 × anchor bolt M10x200, 8 × bolt M10x170, 8 × nut M10, barrel.
Closed risers, a steel frame, another width or railing: change it in uCAD, and the parts are worked out again, with a cut list of the boards to buy. Sizes of the structure are the library’s defaults for a house stair, not an engineer’s calculation for yours.
Another height or width

Will it fit your room?
Open it in uCAD, draw your walls round it and look: turn it the other way, move the turn up or down, change the width. Or tell the AI: “a stair for 11 ft 6 in in a 7 × 10 ft stairwell”, and it draws one that fits.
Same height: L-shaped, landing · L-shaped, winders · U-shaped, landing · U-shaped, winders · Spiral · Square spiral
This stair for 11 ft 3 in · 11 ft 9 in · all heights