Concrete Forms for Foundations Made of Wood

Wood Forms Construction

• Forms for concrete foundations or slabs that are 6 inches tall or shorter are usually made from wooden planks or boards fastened to metal or wood stakes with nails or screws. The stakes are driven into the base underneath the area where the concrete is poured and adjusted to the appropriate slopes and levels using manual or laser levels or chalk string lines. When the frame is perfectly configured, the corners are secured with boards for added stability. To ensure the frames easily release from the hardened concrete, they are conventionally coated with a light layer of oil or a special solution to make the concrete easily separate from the wood. Coated forms are usually reused for future concrete jobs.

Other Wood Concrete Forms

• Projects requiring different heights of concrete slabs use forms of various heights. Sidewalks, driveways and patios have foundations ranging in height from 3 to 12 inches. Since the actual size of a 2-by-4 is 1.5 inches by 3.5 inches, they can only be used to build forms for thinner concrete slabs. Taller lumber with the same thickness is used for thicker concrete slabs. Since the weight of concrete is evenly distributed over the subsurface, wood forms are strong enough to contain the weight while it dries.

Metal Concrete Forms

• Foundations for massive construction projects such as high-rise buildings, commercial piers or bridge bases are taller, ranging in height from 1 to 20 feet. The concrete for these structures covers hundreds to thousands of square feet with incredible weight. To contain the weight of the concrete, high-quality steel forms are used, some weighing thousands of pounds.

Concrete Form Types and Alternatives

• If the edges of a concrete slab are exposed or the design includes arcs and curves, plastic forms are commonly used. They can imprint the outer edges with designs and be molded to created curved slabs for walkways, sidewalks and patios. Concrete forms made from resins or fiberglass are durable, reusable, lightweight and resist sticking to concrete. Insulated concrete forms meld with the concrete as it dries and help keep heat inside the slab.