Platform Construction

Care must be taken when making any alterations to a home's basic wood beam and joist system.

Filed under: Flooring, Safety

Most homes built since the 1920s are wood frame platform construction. A system of wall studs, beams and floor joists forms a supported box that keeps your house standing. As our homeowners near Gettysburg, Pa., discovered, cutting into those beams and floor joists sometimes isn't the best idea.

In platform construction homes, wood beams carry the weight of the walls and the floors. Dimensional lumber supports the floor. They're spaced every 16 to 24 inches. Because they are so necessary to the support system of the house, it's important to know where they can be holed or notched if necessary, say for electrical wires.

To maintain proper support, divide the joist in thirds. Larger holes can be placed in the first and third section of a joist, but not in the middle third. Small holes can be cut anywhere in the joist to run wires, for example. But never cut completely through a joist. That could cause sagging or even collapse.

If you find that you must cut a joist and are not sure where, check with a licensed building contractor. Support from them will mean good support for you.