L-Shaped Steel Stair with Sawtooth Stringers

Opening

Y
in
X
in
W
in

Steps

Z
in
F
in

Flights & turns

P
Q

Structure

A
in
G
in
T

Options

Finishes

Structure

Anthracite RAL 7016

Treads

Natural oak

Loading the 3D view…L-Shaped Steel Stair with Sawtooth Stringers

StairGen Pro › L-Shaped Steel Stair with Sawtooth Stringers

Guide & codes

A variant of the L-shaped steel stair with sawtooth stringers: two zig-zag tube flights and a square landing at the 90° turn. The steps are laid out exactly as on the bracketed L-shaped stair; only the structure changes, and here the stepped profile is on show.

In most cases the L-shaped steel stair calculator is the place to start. This page is for designs that call for sawtooth stringers, such as open stairs in shops, lofts, offices or mezzanines, where the stair is part of the interior.

When to choose this stair

Choose the sawtooth L-shaped stair when a turn with a landing has to look light and the stepped outline is part of the design: the zigzag stringers trace every tread on both sides, and the landing has its own frame and post. It suits open-plan homes, shops and mezzanines where the stair is on show.

Compared with the L-shaped stair with brackets, the structure changes but the step layout does not: the same height, length and number of steps give the same riser and going. The bill of materials is what changes: 2 stringers per flight in 50 × 40 mm tube, no separate brackets, and more cuts and welds at every tooth.

Calculator parameters

Each dimension carries the letter used in the editor and on the drawings.

YTotal rise
default 2,800 mm · 500 to 8,000 mm
Height from the lower floor to the finished upper floor.
XTotal run
default 3,250 mm · 500 to 12,000 mm
Plan length available for the flight (on turning stairs, the upper flight).
WStair width
default 1,000 mm · 500 to 2,500 mm
Clear width of the flight.
ZTread thickness
default 50 mm · 3 to 120 mm
Thickness of the tread (board or plate).
FNosing
default 50 mm · 0 to 100 mm
How far each tread overhangs the one below.
PSteps, lower flight
default 7 · 1 to 25
Steps before the turn.
QSteps, upper flight
default 8 · 2 to 25
Steps after the turn, up to the top.
AStringer depth
default 50 mm · 30 to 300 mm
Depth of the stringer tube.
GStringer width
default 40 mm · 20 to 300 mm
Width of the stringer tube.
TNumber of stringers
default 2 · 1 to 3
One centre stringer, two side stringers or three.

How it's calculated

The total rise Y = 2,800 mm over 16 risers (the landing counts as one) gives 175.0 mm per step. The upper flight, with X = 3,250 mm and Q = 8 steps, leaves a run of 281 mm and a tread depth of 331 mm. Step formula: 631 mm; pitch: 31.9°; verdict: “Comfortable stair”.

Each stringer is broken down into horizontals and uprights of 50 × 40 mm tube. The landing has a frame in the same tube and a corner post, and every part is numbered in the bill of materials and in the DXF, so the shop can cut the whole kit from the list.

Result with the default values

Comfort verdict: Comfortable stair.

Complies with IRC / IBC

Step formula 2R + G631 mm600 – 660 mm
Tread depth331 mm≥ 280 mm
Pitch31.9°30° – 40°
Riser175 mm≤ 197 mm
Going281 mm≥ 254 mm
Clear width1,000 mm≥ 914 mm
Guarding height900 mm≥ 864 mm

Steps

Risers16 pcs
Riser height175 mm
Run (going)281 mm
Tread depth (run + nosing)331 mm
Open riser gap125 mm
Pitch31.9°
Nosing-to-nosing distance331 mm

Structure

Tread area4.969 m²

Building codes

The landing rules are those of any L-shaped stair: under the IRC and Approved Document K the landing may not be narrower than the stair. The welded joints of the teeth are the critical point of this structure and must be checked in the structural design.

The calculator checks comfort (2R + G, going and pitch) and the building code of the country you pick in the panel (here, IRC / IBC for a dwelling): only the limits that code sets for riser, going, 2R + G, width, pitch, risers per flight and guarding. It is for guidance only: always confirm the code in force and local rules.

Building codes by country, with sources

Parts with the default values

The DXF (AutoCAD 2007, in millimetres or inches) carries these parts with their shop marks: one dimensioned sheet per part, the general arrangement and the bill of materials with weights.

What's in the DXF
  • Z1Stringer · horizontalTube 50×40 × 28
  • Z2Stringer · uprightTube 50×40 × 2
  • Z3Stringer · uprightTube 50×40 × 28
  • Z4Stringer · uprightTube 50×40 × 2
  • Z5Stringer · horizontalTube 50×40 × 2
  • E1Treadt=50 × 15
  • M1Landing frameTube 50×40 × 2
  • M2Landing frameTube 50×40 × 2
  • R1Landingt=50 × 1
  • P1PostTube 80×80 × 1
  • B1HandrailTube Ø42.4 × 1
  • B2BalusterRound bar Ø16 × 15
  • B3HandrailTube Ø42.4 × 1

Frequently asked questions

Why choose sawtooth stringers on an L-shaped stair?

Mostly for looks: the tread bears on the full depth of each tooth and the stepped outline is visible from below. In exchange there are more cuts and welds than on a straight stringer with brackets.

Does the step calculation change?

No. With the same opening, the number of steps, the tread depth and the riser height are the same as on the bracketed L-shaped stair; only the structural parts and the weight change.

Can I flip the direction of the turn?

Yes, with the Reverse turn direction switch: the 3D model, the drawings and the DXF are mirrored.