# Staircase rise run formula | Stair formula 2R + T

Staircase rise run formula | Stair formula 2R + T | formula for riser and tread calculation | Thumb rule for number of riser and tread in staircase.

Staircase design depending on local Building Code guideline in your location, to complete the comfort zone, carpenter and the architect design the staircase or stairs according to code. There is a lot of factors is kept in consideration while designing the staircase such as what will be the the relationship between rise and run ratio and their formula, what will be stringer length and what will be landing and ceiling height.

Number of steps or stairs depending on the height of a riser to each thread and it will be also affected by pitch of the stair or staircase. Number of steps or number of stairs or number of riser is same things. Basically all are depending on height of stairs which you will need to go up which all are based on local building Code that says that you need to achieve comfort zone and a relationship between rise and run.

There is a various component of stair or staircase such as step, riser, tread or going, stringer length, waist slab, landing and flight. Tread is the horizontal top portion of a step where foot rests is known as tread. The size of tread or going or run ranges from 270 mm or 11″ for residential buildings and factories, hospitals and public buildings to 300mm or 12″ where large number of persons use the staircase. In some cases nosing is provided the tread is projected outward to increase the space. Maximum nosing will be 1 inch.

Riser is the vertical distance between two successive steps is termed as riser. The size of the riser ranges from 150 mm or 6″ for public buildings to 190 mm 7- 1/4″ for residential buildings and factories. Waist is the thickness of the waist-slab on which steps are made is known as waist. The steps of the staircase resting on waist-slab can be made of bricks or concrete. Going is the horizontal projection between the first and the last riser of an inclined flight. The going should not be less than 250mm or 10″.

There is General Guidelines to follow while desining the staircase- the respective dimensions of tread and riser for all the parallel steps should be the same in consecutive floor of a building. The minimum vertical headroom above any step should be 2 m. Generally, the number of risers or step in a flight should be restricted to twelve. The minimum width of stair should be 3.5 feet. In public building, cinema halls etc., large widths of the stair should be provided. Also angle of inclination is not more than 40 degree to horizontal.

## Staircase rise run formula | Stair formula 2R + T

Usually the Riser (height of step) will be between 7′ – 1/4″ to 7 – 3/4″ and minimum run at least 10″ and maximum to 11″ to 12″. Many carpenter and architect follow the rules to determine comfort rule as rise plus run is equal to 18″ or 2 times rise + run is equal to 25″.

Staircase rise run formula/ stair formula 2R + T :- this is two old formula to design rise and run of stairs, first formula as per thumb rule the Rise plus the Run should equal approximately 17.5 to 18 inches represented as Rise + run = 17.5″ – 18 inches. Second formula of staircase represented as 2R + T which says that two times Rise plus the Run should equal between 24 and 25 inches, but whichever formula you use, your staircase should probably have steps 7 inches high and high and treads 10 to 11 inches deep.

Staircase rise run formula:- as per thumb rule and various code for staircase design says that the Rise plus the Run should equal approximately 17.5 to 18 inches represented as Rise + run = 17.5″ – 18 inches. For example, suppose riser height is 7″ and tread or run size is 11″, then formula for staircase rise and run such as Rise + run = 18 inches (7’+ 11″ = 18″).

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