How to Know Which Interior Walls Are Weight Bearing

The easiest way to determine if walls are load-bearing is to inspect the foundation from the basement.

Many home renovations involve the removal or modification of interior walls. Many of these projects can be done by the do-it-yourselfer without a building permit, but only if the walls do not support the weight of the house. These load-bearing walls distribute the weight of the house and roof to the foundation and must be identified before a serious renovation. Load-bearing walls should not be modified without a building permit and professional guidance. Fortunately, it is relatively easy to identify load-bearing walls if you have access to the attic and basement or crawlspace.

Instructions

1. Inspect the foundation by entering the basement or crawlspace. The foundation is typically made of cinder blocks outlining the perimeter of the house. Generally speaking, all walls standing on top of the foundation are load-bearing.

2. Identify the floor joists from the basement or crawl space. These are usually 2-by-10 feet boards that stretch across the foundation on their sides to support the bottom of the floor. Walls in the house that run parallel to the floor joists are usually not load-bearing, while walls that run perpendicular to them usually bear weight.

3. Look for any support beams in the basement or crawl space. In modern homes, these are usually metal poles that strut the joists from the ground. If you have a finished basement, these support beams are sometimes incorporated into structural walls. These walls will be wider than other walls to contain the poles. Any walls above these beams are probably load-bearing.

4. Access the attic and inspect the direction of the joists, which might be covered with insulation, if you can’t locate the joists from the basement. Interior walls that are parallel to these joists are generally not load-bearing.

Tips & Warnings

• Two walls that come together at an angle in the house’s interior might have an inner beam where they meet that is load-bearing.

• If you are unsure about whether it is safe to modify a wall, contact a structural engineer.

• If you have access to the house’s blueprints, they will detail which walls are load-bearing.

• If the house has had a prior renovation, be careful to consider that exterior add-ons might give a false impression of where the home's foundation lies.

• Walls that are not load-bearing often hide wires and plumbing lines, so do not modify these walls until the electricity has been shut off and you have located any pipes.

References

• Home Building and Remodeling: How to Know if a Wall Is Load Bearing
• Ask the Builder: Load Bearing Wall Identification