Stairs which are straight

These are stairs with no change of direction in any flight between two consecutive floors. Straight stairs can be:

Run straight between destinations with a single flight.
Run straight with a series of flights without changing direction.
Parallel stairs
Angle stairs
Scissor stairs
Straight stairs may change direction at the middle landing. In the case of parallel stairs, the stairs require a complete reversal of direction. In the case of angled stairs, successive flights are at an angle to each other. Scissor stairs consist of a pair of straight runs in opposite directions and placed on opposite sides of the fire wall.