Deflection is the degree to which an element of structure changes shape when a load is applied. When a load produces a deflection on a stringer that is too great, the component may fail. Structural systems and members must be designed to have adequate stiffness to limit deflections. Deflection limits are needed for the comfort of the occupants and so that the structural member's deflection does not cause damage to other components of the supporting construction. Deflection also limits helps reduce cracking of wall finishes (drywall cracks in the corners near the stairs).