If you are about to do a major house renovation, it is important to know which wall is load bearing and which isn't. Load bearing walls are ones that hold or transfer a structure's weight load from one section to another. If you take down part of or all of a non-load bearing wall, then what's left of the structure will stay intact. But if you take down all or part of a load bearing wall, part or all of the structure will most likely collapse. It's very crucial to know which one is which.
There are several ways to determine if your wall is a load bearing wall. Identifying load bearing walls is more difficult in newer structures than in older ones. Most of the older structures use all of the exterior walls as load bearing walls, while some much newer homes use only the front and back walls to bear the structure's load. Never attempt to do a renovation without knowing this important information, as collapsing walls can be fatal.
Step 1 - Check the Blueprints
The best place to start looking is on your home's blueprints. These plans should clearly indicate which walls are load-bearing, and even if significant alterations have been made, they'll give a good sense of where most of them are.
Step 2 - Check the Basement
If you don't have your home's blueprints or they don't indicate which walls are load bearing, start looking in the lowest part of your home, the basement. If you don't have a basement, start at the concrete pad.
Step 3 - Check the Walls
Look for the walls that sit on the foundation walls. They support the weight of the roof and are load bearing walls. Any exterior wall that rests on the foundation sill is considered a load bearing structure.
Step 4 - Check the First Floor
While you're in the basement, look at the first floor joists. Find the walls that run parallel to those joists. Those are non-load bearing walls.
Step 5 - Check the Center of the House
On the first and second floors of the house, locate any wall that sits comparatively in the center of the house and parallel above the center basement beam. Those are most likely load bearing walls.
Step 6 - Check Perpendicular Walls
Most often, any wall that runs perpendicular to floor joists will be a load bearing wall, while those that lay parallel to floor joists are not.
Step 7 - Check the Posts or Columns
Another visual cue of load bearing walls are those that end in large posts or columns. Some columns simply appear to be decorative, but it probably helps support the weight of other walls and portions of the roof above.
Step 8 - Consult a Professional
If you have any doubt at all as to which walls in your home are load bearing walls, consult with a professional prior to modifying your existing structure. Modifying or moving a load bearing wall without proper bracing can cause not only structural damage and collapsing wall events, but can be fatal to those inside the home.