L-shaped winder stairs calculator with 90 degree turn KALK.PRO allows you to get a ready-made design project online without a specialized knowledge and education, based on measurements of the existing Stairwell opening.
As a result of calculations, you'll get:
- all necessary staircase dimensions and technical drawings,
- an optimal amount of materials required for building structure,
- detailed drawings of the assembled structure and all elements separately,
- an adaptive 3D model in real proportions with a separate set of functional elements,
- and recommendations for creating the most convenient and ergonomic design.
Please make sure your stair design complies with all local building codes and regulations requirements! It is very crucial step.
Staircase with winder treads is significantly space saving construction, in comparison to a staircase with a landing. Winder treads (wider at one side, do not have parallel edges) change the direction of the staircase, turn the flight. Kite winder stairs - L-shaped sraircase design consisted of 3 winder steps in a turn of 90 degrees (middle step is a kite winder).
Calculation of winder staircase dimensions, step by step
- Step 1. Select the number of winder steps - 2 pcs, 3 pcs, 4 pcs, N pcs ( 3 pcs by default).
- Step 2. Select the appropriate units of measurement (mm, cm, m, inches, ft) and the color of drawings - b&w, color.
- Step 3. Determine the type of staircase rotation - with a left turn (left-handed stairs), with a right turn (right-handed).
- Step 4. Select the method of newel post / winder treads joint: notched treads are fitted into notched newel; newel installation onto the surface of treads (f.e. with fasteners).
- Step 5. Measure and enter the dimensions of staircase and stairwell opening - the width of the stairs, the Total Run and Total Rise - FFL to FFL (if the top step is at the level of the upper floor, the height of the opening = the height of the stairs).
- Step 6. Specify the parameters of steps, risers (you can disable risers calculation, if necessary, by clicking on the checkbox) - the number of steps, thickness, nosing overhang, top step is below the upper floor level or at the level.
- Step 7. Enter the stair stringer parameters, posts and joists - supporting the 90 degree turn of the stairs.
- Step 8. Determine the dimensions of the railing system.
- Step 9. The parameters of the upper floor slab and walls are used only for 3D-visualization and do not affect the final results.
- Step 10. Confirm the entered values and start the calculation of the winder stairs using the "Calculate" button.
Finally, you get an estimated material quantity, the dimensions of staircase elements. Click on the "View in 3D" tab to view interactive 3D model. On the tab "Download" you can choose saving method of your calculation results and drawings or 3d objects.
Design features in the drawings
To create the most comfortable stair structure it is recommended to select the steps dimensions on the basis of the universal formula of a “perfect staircase” by French engineer François Blondel. If the step width decreases, it is necessary to increase its height, and vice versa - if the step width increases, its height must be reduced, while maintaining the step length in the range of 630-650 mm.
Blondel's formula: 2 × Rise + Run = 63 ÷ 65 cm
- Rise – the height of the step;
- Run – tread width or going;
- 63 ÷ 65 cm average stride length of a person. The IRC limit gives a 2r+R of 25 ½
One more rule "Rise + Run" says that rise plus run should equal 18 inches (17 -19). The IRC limit gives an r+R of 17 ¾ ”
Your staircase should be compliant with national building codes, local regulations (depending on country and city you live in):
- BCA (Building Code of Australia)
- UK Building Regulations 2010 Part K
- IRC (International Residential Code) for residential buildings, IBC (International Building Code) — the United States of America
- NBC (National Building Code of India).
The International Residential Code (IRC 2018) says :
- "R3184.108.40.206.1 Winder treads. Winder treads shall have a tread depth of not less than 10 inches (254 mm) measured between the vertical planes of the foremost projection of adjacent treads at the intersections with the walkline . Winder treads shall have a tread depth of not less than 6 inches (152 mm) at any point within the clear width of the stair. Within any flight of stairs, the largest winder tread depth at the walkline shall not exceed the smallest winder tread by more than 3/8 inch (9.5 mm)..."
- "R311.7.4 Walkline. The walkline across winder treads and landings shall be concentric to the turn and parallel to the direction of travel entering and exiting the turn. The walkline shall be located 12 inches (305 mm) from the inside of the turn. The 12-inch (305 mm) dimension shall be measured from the widest point of the clear stair width at the walking surface..."
- Minimum Going or Run (width of tread without nosing overhang) must be not less than 10 inches (254 mm), according to R3220.127.116.11.
- Headroom - shall be not less than 2032 mm or 6 ft 8 inch (R311.7.2).
- Handrail height - 864 ÷ 965 mm or 34 ÷ 38 inches (R318.104.22.168)
- Risers or steps height - max. height 196 mm or 7 3/4 inches (R322.214.171.124)
- Nosing projection - 19 mm ÷ 32 mm (3/4 ÷ 1 1/4 inches), according to R3126.96.36.199.
- Staircase clear width - not less than 914 mm, 36 inches (R311.7.1)
- Vertical Rise of staircase flight - less than 3835 mm or 151 inches (R311.7.3)
Using KALK.PRO is very simple – requires no special knowledge, just enter a few values and you will be able to get a professional design of the staircase with winder steps for free (drawings - are available for premium users).