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Staircase calculator
Work out how many steps a floor height takes, the riser and tread they come to, the length of the stair and its landing, and the concrete, cement, sand, crush and steel for an RCC stair, checked against the limits in Pakistan's building regulations.
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Calculator
Plan your stair
Give the floor-to-floor height, the riser and tread you want, and the stair's width and layout. The answer is the steps, the length of the stair and its landing, the checks, and the concrete and steel to build it.
Your staircase
- Riser
- 6.3 inThe height shared by 20 risers
- Going
- 7'-6"The longer flight, 9 treads
- Landing
- 7' x 3'-6"Across both flights
- Stair in plan
- 11' x 7'Flights and landing
Checks
- Riser, up to 7.5 inLDA and FDA; DHA Karachi allows 7 in
- Meets it
- Tread, at least 10 in
- Meets it
- Risers in a flight, up to 15Then a landing, LDA
- 10, meets it
- Width, at least 3'-6"LDA, for a house; DHA Islamabad-Rawalpindi asks 3'
- Meets it
- Comfort, 2R + T of 24 to 25 inTwice the riser plus the tread
- 22.6 in, short steps
Steps of 22.6 in (2R + T) feel short to climb. At a 6.3 in riser, a tread of 11.4 to 12.4 in suits, if the stairwell has the length; with 10 in treads, a riser of 7 in or so does.
Headroom: keep 7 ft clear above every step and under any beam. Leave the floor above open over the whole stair, 11' x 7', so the upper flight reaches it with room overhead.
Concrete
- Waist slab2 flights, 9.15 and 9.15 ft on the slope
- 26.7 cft
- Steps18 triangles under the treads
- 13.8 cft
- Landing7' x 3'-6"
- 10.2 cft
- Concrete
- 50.7 cft
Materials to buy
- Cement50 kg bags, 1:2:4 (M15), 2% over
- 10 bags
- Sand0.23 of a 100 cft trolley, 5% over
- 23.4 cft
- Crush0.47 of a trolley, 5% over
- 46.8 cft
- SteelAn estimate, from the bars below
- 104.4 kg
- ShutteringUnder the flights and landing 89, risers 37, open sides 12 sq ft
- 137 sq ft
- WaterTo mix, at 0.5 of the cement's weight
- 223 litres
Steel estimate
- Main bars, 4 sutar, 1/2 in16 bars, 200 ft with 40d into the floors at each end
- 60.6 kg
- Distribution bars, 3 sutar, 3/8 in26 bars of 3'-6"
- 15.5 kg
- Landing mesh
- 20.4 kg
- Laps and bends
- 4.8 kg
- Waste, 3%
- 3.1 kg
- Steel to buy
- 104.4 kg
Quantities for budgeting. The riser, tread, waist and bars come from the architect's and structural engineer's drawings, within your authority's rules. Leaves out the finish on the steps, the railing, and the slab at the top, which belongs to the floor above.
Reference
Steps for common floor heights
How many risers a floor height takes, and how high each one comes out.
| Floor to floor | Risers, up to 6.5 in | Each (in) | Risers, up to 7 in | Each (in) |
|---|---|---|---|---|
| 9' | 17 | 6.35 | 16 | 6.75 |
| 9'-6" | 18 | 6.33 | 17 | 6.71 |
| 10' | 19 | 6.32 | 18 | 6.67 |
| 10'-6" | 20 | 6.3 | 18 | 7 |
| 11' | 21 | 6.29 | 19 | 6.95 |
| 11'-6" | 22 | 6.27 | 20 | 6.9 |
| 12' | 23 | 6.26 | 21 | 6.86 |
A straight flight has one tread fewer than its risers, and a dog-leg stair two fewer, with a landing between its flights.
How it is worked out
From floor height to steps and materials
The number of steps is the floor-to-floor height divided by the riser you want, rounded up so no step is higher, and the height is then shared equally between them: 10'-6" (126 in) at up to 6.5 in takes 20 risers of 6.3 in. Measure from finished floor to finished floor, with the floor finishes, or the first or last step comes out a different height from the rest.
Each flight has one tread fewer than it has risers, because its last riser steps up onto the landing or the floor. The going, the flight's length in plan, is its treads times the tread. A dog-leg stair shares the risers between two flights that turn back at a landing, which runs across both flights and is as deep as one is wide, and never under 3'-6".
The LDA's 2019 regulations, which the FDA's repeat, allow a riser of up to 7.5 in, a tread of at least 10 in and no more than 15 risers before a landing, in a stair at least 3'-6" wide in a house of up to three storeys. DHA Karachi caps a house's riser at 7 in; DHA Islamabad-Rawalpindi allows 7.5 in and a 3' stair. For comfort, twice the riser plus the tread should come to 24 to 25 in.
Under each flight is a waist slab, an inclined slab whose length is the slope over the flight's going and rise, and under every tread a triangle of concrete, the riser times the tread over two. The landing is a slab as thick as the waist. The cement, sand and crush follow the same rules as the Material Planner in Smart Construction: 1.54 times the wet volume in dry materials, 2% more cement in whole bags, 5% more sand and crush.
The steel is an estimate from a bar layout: main bars along each flight, running 40 times their diameter into the floor or landing at each end, distribution bars across them, the same mesh over the landing, then 5% for laps and bends and 3% for waste. The shuttering is the underside of the flights and the landing, a board for every riser and one open side of each flight.
The riser, the tread, the waist and the bars are for the architect and the structural engineer to set, within your authority's rules. The calculator works out the steps and the quantities from them; it does not design a stair or check one.
On site
Terms you will hear
- Riser
- The height of one step, and the upright face that closes it.
- Tread
- The part of a step you stand on, measured from one nosing to the next.
- Going
- The length of a flight in plan, its treads added up.
- Flight
- An unbroken run of steps between two floors or landings.
- Landing
- The level platform where a stair turns or rests, at least as deep as the stair is wide.
- Waist slab
- The inclined reinforced concrete slab under a flight, measured at its thinnest, below the steps.
- Dog-leg stair
- Two flights side by side that turn back on each other at a half landing, the usual stair in a Pakistani house.
- Headroom
- The clear height above a step, measured straight up from its edge to the slab or beam above.
Questions
Staircase questions
Still have a question?
Ask our team during Pakistan business hours, in English or Urdu.
+92 333 2466662Chat on WhatsAppHow many steps for a 10 feet height?
At a riser of up to 6.5 in, 10 ft (120 in) takes 19 risers of 6.32 in: 18 treads in one straight flight, or 17 treads and a landing in a dog-leg stair of 10 and 9 risers. At up to 7 in it is 18 risers of 6.67 in. The steps are always the height divided by the riser, rounded up.
What riser and tread do Pakistan's building regulations allow for a house?
The LDA's Building and Zoning Regulations 2019 allow a riser of up to 7.5 in and a tread of at least 10 in, with no more than 15 risers between landings and a clear width of 3'-6" in a house of up to three storeys; the FDA's 2020 regulations say the same. DHA Karachi's 2020 regulations cap a house's riser at 7 in, and DHA Islamabad-Rawalpindi's allow 7.5 in with a 3' width. Check your own authority's current rules before the map is drawn.
What is the 2R + T rule for stairs?
Twice the riser plus the tread should come to 24 to 25 in, which matches a normal stride, so the stair is neither choppy nor a stretch. A 7 in riser with a 10 to 11 in tread fits it, and so does a 6.5 in riser with an 11 to 12 in tread. A 6.5 in riser with a 10 in tread comes to 23 in: allowed, but short-stepped.
How is a dog-leg staircase worked out?
Divide the floor height by the riser for the risers, share them between two flights, and give each flight one tread fewer than its risers. For a 10'-6" floor at up to 6.5 in: 20 risers of 6.3 in, two flights of 10, each with 9 treads of 10 in, a going of 7'-6", and a 7' x 3'-6" landing for 3'-6" flights. The stair takes 11' x 7' in plan.
How much headroom does a staircase need?
Keep at least 7 ft clear above every step, measured straight up from the step edges to the slab or beam above; DHA Islamabad-Rawalpindi asks for 7 ft under beams and landings in a stair hall. Over a straight flight with 6.3 in risers and 10 in treads, that means leaving the floor above open for about 12' back from the top step. A dog-leg stair needs the floor above open over the whole stair.
How much concrete and steel does a staircase take?
A dog-leg stair for a 10'-6" floor, 3'-6" wide with a 5 in waist, takes about 50.7 cft of concrete: 10 bags of cement, 23.4 cft of sand and 46.8 cft of crush in 1:2:4, and about 104 kg of steel with 4 sutar main bars every 6 in. The bar bending schedule on the drawing gives the exact steel.
How wide should a staircase be?
At least 3'-6" clear in a house under the LDA's rules, and 4 ft in apartment buildings of up to five storeys. 3'-6" to 4 ft suits most houses; a wider stair makes furniture easier to carry up but takes a longer, wider stairwell.
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