Stair shapes

When choosing the shape of the staircase, the available open space for it must be considered. Wide low rise staircases are comfortable, but consume most of the floor space. The advantage of the straight staircase is its cheaper price and easy installation. The L- and U-shaped staircases with the landings are more comfortable and safer than the ones with turning treads. Spiral staircases are indeed less space consuming, but are also more difficult to walk on and bigger objects (like furniture) may not be possible to be transported up or down them at all.

The alternating tread stair is a staircase with a special shape. It is the best choice if the rise of the staircase is steep and the conditions do not allow a classical staircase to be used. That is mostly the case for attic staircases etc.