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STAIRS (стЕаз)

Stairs and stairwells are divided into:1 – internal, placed in stairwells;

2 – internal open;

3 – external open;

•conventional staircases:

Л1 – with glazed or open openings in the exterior walls on each floor;Л2 – with natural light through glazed or open openings in the coating;

• smoke-free stairs

Н1 – with the entrance through the outdoor air zone through balcony;

Н2 – with air supply to the stairwell in case of fire;

Н3 – with the entrance to the stairwell from the floor through the tambour airlock with air supply (permanent or in case of fire).

The height of a public building floor is usually 3.3 m; 3.6 m; 4.2 m. Stairs are

designed according to this calculation. Stairs can be one-, two-, three - and

four-step. The staircase consists of a tread and a riser. Tread width is 300 mm,

riser height is 150 mm.

The width of a stairs flight in public buildings must be:

•1,35 m — for the main staircases leading to the rooms for people;

•1,2 m — for escape staircases;

•0,9 m — for stairs leading to a room with up to 5 people at the same time. The width of the staircases must be at least the width of the stairwell, the

intermediate platform between the stairwell is 1 m.

The slope of staircases in aboveground floors should be no more than 1 : 2.

The slope of stairs leading to the basement floors, to the attic, not for evacuation of people, should be 1 : 1.5. The height of staircases should be at least 900 mm.

The number of ascents in one flight of stairs between the platforms must be at least three and no more than 16.

Stairwells should be designed with natural light through openings in the

exterior walls, in buildings up to three floors high, it is possible to use

overhead lighting through a light lantern. In addition, it is necessary to

ventilate the stairwell -1.2 m2 within each floor.

Types of open stairs in public buildings:

a — one — step; b — two — step; c — two-step with a turn; d-three-step; d-branched three-step; e — branched four-step

GEOMETRIC CONSTRUCTION OF STAIRS