Building an outdoor deck is a popular home-improvement project. Many homeowners that undertake this job may wonder the best place to start. As with most construction projects, a solid foundation is vital in order to have a long-lasting and stable finished product. While many homemade decks have skids made from lumber or precast concrete blocks as the basis for their foundation, these methods have a much higher likelihood of settling and are poor choices for a deck on a slope. Concrete piers are widely recognized as the best way to support a deck.
Refer to your deck plan, and mark locations for the piers on the ground.
Dig a hole for the cylindrical concrete form that is at least 6 inches below the frost line for your area, or 36 inches deep, whichever is greater. This hole should be about 6 inches larger in diameter than the concrete form so as to allow for backfill.
Use the hand tamper to firmly compact the soil firmly. Add 4 inches of finely crushed gravel, and compact again.
Set the form into the hole, and make sure it is plumb. Begin to backfill between the form and the side of the hole, stopping every so often to compact the soil. Trim the top of the form to a height about 2 inches higher than the surrounding finished grade.
Prepare the ready-mix concrete and pour it into the pier. Use a 2-by-4inch piece of lumber plunged into the concrete and work around to remove any air pockets. Pour the concrete to your planned height for the joist anchors of your deck.
Use a trowel to float the top of the concrete. Add joist anchors or post bases to the center of the concrete according to your deck plan, and allow the concrete to cure for 24 hours before moving on to the rest of your deck construction.