Normal stairs:

• Going up stairs is difficult terrain (each 5 feet of movement costs an extra 5 feet).

• Going down is usually normal terrain unless other terrain rules apply.

Shoddy or damaged stairs:

• Count as uneven ground in addition to difficult terrain.

• Uneven ground means creatures on it must Balance (Acrobatics) or risk falling prone; they are flat‑footed while on it and might need Reflex saves when hit or failing certain checks.

Oversized stairs (built for larger creatures):

• Are greater difficult terrain both up and down for significantly smaller creatures, or may require them to Climb on every step instead of simply Striding.