install forms

Step-by-Step

Except for stepped footings (see Step 4), the only forming materials you'll need are 2x4s for the footing rails and 1x4s for stakes. Position the stakes (see Building Forms for Slabs, Related Projects), then secure the rails to them, making sure the top of each rail is even with or slightly above the top of the stakes.

trench/stake

If the soil is firm enough to hold its shape when filled with wet concrete, simply dig a trench footing. Keep the sides of the trench even to avoid wasting concrete. For screeding guides, center a row of stakes about 4 feet apart; check the height of the stakes with a line level.

level forms

Every few feet along the length of the form, use a carpenter's level to make sure parallel forms are the same height. Also, check to see that the forms are level lengthwise. Drive stakes every 4 feet to anchor the forms securely. Make sure the stakes penetrate at least 6 inches below the bottom of the footing trench that you will dig (see Step 3) to ensure that the form boards will be secure.

dig trench

Once you are satisfied that the forms are level and secure, excavate an additional 5 to 6 inches of earth; the total depth of the footing should be no less than 8 inches. Keep the sides of the trench even with the form as you dig. Check the forms again to see that they are level and aligned properly.

step down

If your site is sloped, you can step the footings down to save concrete. If you have wood forms, use 2x8s and extra stakes. For an earth form (lower left), make a wood riser that wedges securely between the two levels. Stepped forms should rise no more than 2 feet per step; the upper and lower forms should overlap by at least 2 feet.