How to build stairs (part 2)

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Top edge of the forefront of all treads shall be rounded. It prevents rapid wear and shearing of stairs. Radius of rounding shall be from 4 to 8 mm. Bottom edge of the forefront of all treads may have different shape. The depth of treads (as well as the going) shall be the same throughout the length of the stairs flight on center of the pitch line. The riser height of all steps shall also be the same, but if there becomes necessary to change the riser height of some step (for example, of the last one) maximum deviation from the initial size shall make no more than 5 mm.


























Fig. Forefront of a tread


The treads may be supplemented with risers. The riser communicates additional strength to treads, covers the space under the staircase, and makes the staircase safer. The thickness of risers usually makes 16-20 mm. To eliminate little inflexion of treads, which causes squeaking, the central part of the riser is made 2-3 mm wider. The riser is fastened after pretensioning of treads. On the drawings in the section  Stair Plans risers are also made with 3 mm widening in the central part.















Fig. Widening of the central part of a riser












Fig. Connection of a riser to the upper part of the tread

















Fig. Connection of a riser to the lower part of the tread


Tread nosing shall necessarily be executed for both closed (with risers) and open (without risers) stairs. Whereby, for closed stairs it is a protrusion of the tread against the riser, and for open stairs it is a protrusion of the forefront of the tread against the back edge of the tread located lower. This protrusion shall be no less than 30 mm. It allows enlarging the depth of the tread. On the drawings in the section Stair Plans  the nosing is also equal to 30 mm.
All the treads shall be installed true-horizontal.

















Fig. Nosing


A continuous series of treads connecting different levels is called a flight of stairs or flight of steps. The length of the flight of stairs in plan depends on the chosen correlations between riser height r and going g, as well as on the quantity of treads. Minimal quantity of treads in one flight shall be no less than 3: bottom frame tread, basic tread, and top frame tread. Maximum quantity of treads in one flight shall be no more than 16.


The value of the width of a flight in plan determines only the overall width of the staircase. The value determining the width of the flight immediately for walking is called usable width. It should be remembered that the usable width of stairs is less than the overall width. Usable width value does not include the width of handrails and closed strings. That is why for calculations in the course of stairs designing you shall remember about this difference. Minimum permissible usable width for domestic stairs is considered to be the value of 800 mm.





























Fig. Usable width of a flight of stairs


Closed and open strings constitute primary bearing elements of the staircase. They will be described in detail in the section Stairs Models.

Landing is a horizontal plane located between two flights of stairs. They recognize bottom (aflat with the floor of the first level), storey (aflat with the floor of the second level), and intermediate landings. Intermediate landings allow changing a direction, and also serve as a place for rest when you go up-stairs. Basic dimensions of the landing are width and depth.
The width of the intermediate landing shall be equal to the width of the flight of stairs connected with it.
















Fig. Landing


For stairs with a turn by 90 or 180 degrees, the depth of the landing shall be longer by half of the tread width in each direction, or by the whole tread width in one direction.






















Fig. Depth of the landing


In case the landing is located between the flights going in the same direction, minimal depth of the landing shall amount to the sum of the step length and the depth of one tread in plan. If the depth of the landing shall be more than the value received, the increase shall be a multiple of the minimal depth value.










Fig. Minimal depth of the landing


Headroom is a size of vertical opening of the staircase in the clear from the tread forefront up to the low point of any structural element above it (ceiling, beam, flight of stairs, roof).
According to general rules for comfortable and safe usage of stairs this size shall make vertically no less than 2100 mm.
























Fig. Headroom


Climbing at any height is always connected with defined risk. And going up the staircase in the house is no exception. To protect people from falling down and to make walking comfortable and convenient, this is an intended application of handrails. The space under handrails shall be necessarily closed.
The space filling can be executed in different ways. For instance, these can be wooden turned or rectangular balusters, or metal balusters or forged fencing. Besides their functional role, handrails and balusters also perform a decorative function underlining the elegance of stairs. Read more about great variety of forms and designs of balusters in the section Balusters.
Basic parameters influencing safety are the height of handrails and the distance between balusters. The height of handrails when measuring from the tread forefront shall be not less than 900 mm. The height of handrails on the balcony and on the intermediate landings shall make no less than 1100 mm. Handrails shall always be parallel to the pitch line.
The distance between balusters shall be not more than 10 cm at the broadest opening. For open string stairs when the baserail is used, maximal distance between its bottom and the tread shall make no more than 15 cm. If there are children in the house, the handrails shall be designed in such a way as to eliminate a possibility of children's climbing over the handrails.
If the stairs width is above 1000 mm, the handrails shall be installed on either side of the flight. The handrails shall be continuous throughout the length of the stairs flight. The only exception to this rule is intermediate newel post on turn, which can interrupt the handrails. The handrails running along the wall shall be mounted minimum 38 mm away from it.




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- Stairs Models

- Stairs Types

- How to calculate Stairs