Columns and Beams

Wood or steel columns are usually used in the basement to support beams, which, in turn, support the inner portion of the first-floor joists as well as loads from upper floors transferred through walls, floors and posts.

Cylindrical structural-steel columns (called “teleposts”) with adjustable lengths and bearing plates at both ends are commonly used to support beams. The top plate should be as wide as the beam it supports and either be bolted to the flange where a steel beam is used or nailed where a wood beam is used.

Wood columns at least 140 × 140 mm (6 × 6 in. nominal) may be solid or built-up from 38 mm (2 in. nominal) lumber. Use at least 76 mm (3 in.) nails spaced at 300 mm (12 in.) on centre to fasten the built-up members together. A wood column should be the same width as the beam it supports and be cut square to ensure even bearing at the top and bottom. Fasten the column to the beam at the top and install dampproofing material such as 0.15 mm (6 mil) polyethylene or Type S roll roofing to separate it from the concrete at the bottom.

Columns are usually spaced 2.4 to 3.0 m (8 to 10 ft.) apart, depending on the loading and strength of the beam they support. The footings for basement columns must be sized to suit the column spacing, the span of the supported joists, the number of floors supported and the soil-bearing pressure.

Source : Canada Mortgage and Housing Corporation (CMHC)