The external stairs needs a harder resistance due to changes in the atmospheric conditions. The material used could be the plexi-glass and the iron with special treatment to increase the grip. External stairs could also use classic material with special wood like teak or LLroko classic but perfect for bad weather which is coated in a special varnish and does not need to be renovated.
The most important thing with these stairs is the safety made possible by bigger banisters, use of iron and the design that does not allow the rain to impregnate. The Spedaliere Company gives special attention to the style of these stairs because it is the first impression of the building.