Forcing Open Doors

Usually a creature can open a door simply by using a minor action (see “Action Types"). Sometimes, though, adventurers encounter doors that are stuck or locked. Forcing open a stuck or a locked door requires a standard action and a successful Strength check.
    The Force Open Doors table shows some sample doors and includes the Strength check DC to force or break them open.

Strength Check to...DC
Break down wooden door13
Break down reinforced door16
Break down barred door20
Break down iron door23
Break down adamantine door27
Break through force portal30
Force open wooden portcullis21
Force open iron portcullis28
Force open adamantine portcullis35

Published in Dungeon Master's Guide, page(s) 64, Rules Compendium, page(s) 175.