Like the human body, a house has a skeleton that gives it support, shape and a framework for outer coverings.

A house's skeleton is called the frame. Though some new homes utilize steel framing, most houses are made of wooden beams, floor joists, walls studs, roof rafters and related components.

To insure the structure's strength, these parts are sized and connected in accord with building codes that are based on basic load engineering principles.

It's important to know which parts are critical to a house's structure so that you don't compromise its strength when remodeling or doing work that involves cutting into framing members.

For example, if you remove part or all of a load-bearing wall without reinforcing the structure, floors and roof may sag and windows and doors may stick. Or worse, part of the house may collapse.

Non-bearing walls may be either perpendicular or parallel to joists or rafters. They often may be identified from under the house, because they're not supported by a foundation or beam.

Because they don't support loads, they usually can be removed without compromising a structure's strength.

Foundation and footing deliver loads from the house down to solid soil. The footing is wider than the foundation to spread out loads.

Weight of roof materials and loads compresses roof rafters, which pull ceiling joists from each end, placing them under tension.

The resulting triangle transfers roof loads out to rafter ends where the weight is carried by supporting walls.

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