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Staircase is an important component of a building which helps in commuting between 2 floors. Improperly designed staircases can cause severe injury and even death if the necessary guidelines and building codes are not followed properly. Hence, the design of stairs as per the set guidelines is important for the safety purpose.
In this article, we discuss the general guidelines for height, tread, riser and the headroom of the staircase.
Height or Rise of Staircase
Rise is the overall height of the entire staircase, from the lowest point to the highest point. Rise is an important measurement for determining the location and placing of landing.
Typically, a landing must be provided for every 12 feet (365.8 cm) of rise, as per fire safety codes. There is no other code for rise length or height of the staircase other than landing as every staircase is different and depends upon the height of the floor.
|Type of Building||Minimum Width|
|Residential||1.00 - 1.25 m|
|Residential hotel||1.5 m|
The minimum width of stairs for the different types of buildings is shown in the table above. If the stair width is more than the minimum specified width, handrails are to installed in the stairs. The handrails introduced shall not project more than 4 ½ inches on either side.
Narrow stairs make it more difficult to carry items up and down the stairs. Stairs that are not wide enough can be dangerous during a fire exit, as they might impede the escape.
Headroom for Stairs
The clear distance between the slope line adjoining the tread to the floor of the above floor is known as headroom. The minimum headroom dimension is 6 feet 8 inches.
Vertical Rise for Stairs
Stairs cannot be continued without having a landing or floor level that breaks up the flight of stairs. As per the code specifications, the maximum vertical height of 147 inches (12 feet 3 inches) should be provided between landings or floor levels for a flight of stairs.
If the distance between floor levels exceed 147 inches, the flight of stairs would require a level landing somewhere in-between to break up the flight of stairs.
The vertical distance between the two adjacent treads is known as riser height. The height of the riser prescribed as per the codes is not more than 7 ¾ inches in height. All the risers must be of the same height. The tallest riser cannot differ from the smallest by more than 0.37 inch.
Risers may slope up to 30 degrees from the underside of the tread. They may be solid, open or have any pattern, provided that spaces do not allow a 4-inch-diameter sphere to pass. This prevents small children from getting their heads stuck in between risers.
The maximum height of riser shall be 19 cm for residential high rise buildings and 15 cm in the case of other buildings, they shall be limited to 12 per flight.
The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge.
Tread size (min 10 in / 25.4cm) is fixed by the average adult foot size, although it is not necessary to be able to fit your entire foot on a tread in order to walk up the stairs to be both comfortable and safe.
The minimum size of the tread is given as 11 inches. If nosing is made for the tread material, then the minimum depth of the tread can be taken as 10 inches or 25.4 cm.
The projection of nosing shall not be more than 1 ¼ inches and no less than ¾ inch. Again the tolerance of treads or nosing should be no more than 0.37 inches.
General Points to Remember while Constructing Stairs
- Handrails shall be provided with a minimum height of 100 cm from the center of the tread.
- Interior stairs shall be constructed of non-combustible material throughout.
- The main staircase and fire escape staircase shall be continuous from the ground floor to the terrace level.
- No electrical shafts/AC ducts or gas pipe etc. shall pass through the staircase. The lift shall not open in staircase landing.