From a structural point of view, there are several different types of stairs that are differentiated not only on the basis of their structural shape, but also with regard to their necessity, position and shape. What is the difference between a necessary staircase and an unnecessary one?? What does a ladder look like? And which type of staircase does the push-in staircase belong to? An overview.
Necessary and unnecessary stairs
Building regulations make a distinction between necessary and unnecessary stairs. The staircase standard DIN 18065 defines a necessary staircase as part of the escape route from buildings not at ground level.
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Structurally necessary stairs must be available in sufficient number and size so that all residents can get to safety in the event of danger. The distance from the apartment door to the rescue staircase must not be too great.
Stairs that are not structurally necessary are stairs that were built in addition to the safety-relevant facilities. They are not subject to such strict standards as the necessary stairs, but they must also meet strict safety regulations.
External and internal stairs
Outside stairs are of course outside a building. Outdoor stairs should be made of weather-resistant material with a non-slip surface. The treads need a gradient of up to 1% so that the rainwater can drain away.
External stairs usually have a lower gradient than internal stairs, the gradient ratio is usually 16/31 to 12/39. An intermediate landing should be installed after a maximum of 12 steps. Internal stairs are enclosed by the building and are therefore more difficult to access for rescue workers.
Special safety stairwells must be lockable smoke-tight, they are usually only used in high-rise buildings. In house building, there are easements with regard to the building requirements, for example no completely closed, fire-safe stairwells are necessary here.
Overview of other types of stairs
- Ladder or steep staircase with an incline of at least 45 to 75 degrees: only permitted for access to the top floor without a lounge (if the incline exceeds 75 degrees, it is a ladder)
- Folding staircase as a classic attic staircase: foldable or extendable staircase (slide-in staircase): also only intended as access to uninhabited attic spaces, permanently attached
- Alternating step staircase as space-saving staircase, which is not required by building regulations: also intended as a storage staircase, staggered step to cope with the steep incline (normal step depth alternating left and right - therefore also called samba staircase)
- Stringer staircase with steps between the actual support structure, main support beams are next to the steps
- Stile staircase as a saddled staircase, the steps of which are on the supporting structure
- Spiral staircase with a central support, which is known as a spindle: the steps wind, so to speak, around the load-bearing spindle located in the middle
- Carrying bolt staircase with free ends of the steps: attached to the wall on one side by means of a stringer or spar, no risers - almost seems to be floating
- Folded staircase as a "free-floating" staircase without a visible substructure: the folding system of risers and treads stabilizes this staircase