How to Identify Weight-Bearing Walls
- 1). Assume that all exterior walls are load-bearing. There may be exceptions, but in virtually every house the outside walls where a roof connects will bear at least some of the load from that roof. Not all loads will necessarily be the same. In some houses, the side walls on a gable-roofed house may bear more load than the end walls. Consult your house plan if it is available; it should identify all load-bearing walls.
- 2). Start with the house's foundation. Note the location of all walls resting on those walls or piers. Look for any internal piers, posts or other supports on beams or joists that go from one wall to another; any wall located above such supports probably will bear some load. Any wall parallel to a floor joist and above it likely is not load-bearing; if it goes across joists or beams, it probably is load-bearing.
- 3). Look in an attic, especially on multilevel houses. As with floor joists, walls paralleling joists probably aren't load-bearing; those across joists probably are. Match second-story walls with ground-level walls. Upper walls resting on top of lower walls probably are putting some weight on the lower walls. Examine the roof framing. Rafters and trusses may have braces that run from the sloping rafters to a bottom chord or joist. Truss chords that extend wall to wall generally support the roof without help from the walls below. Individual rafters may have vertical or angled braces that connect to a joist supported by a wall.
- 4). Call a professional engineer if you are unsure about any wall. Some walls can look like simple internal walls but conceal a post or pillar inside that supports a wall above. Never assume that a short or partial wall is not load-bearing, because it may hide an internal support.
Source...