Things You'll Need
Pre-formed concrete piers
Pier and beam refers to the type of foundation where there is a concrete block supporting the floor joists of a deck sitting directly above it. When you are building a deck, there are a number of options for the type of footing you are going to use, and pier and beam is one of the stronger options. If you are building an addition to a pier and beam deck, setting the footing is the most important step.
Measure out from the end of the current deck in the location where you will be building the addition. Hammer a small stake into the ground to mark the corner locations. Verify the corners are flush and straight with the other corners.
Mark the areas where the holes for the pier foundation will be located. Hammer a stake into the ground every 8 feet throughout the area where you have the addition. Place the stakes further into the ground than the corner pieces so you can differentiate between the two.
Dig holes into the locations marked by the stakes. The holes should be 16 inches around and 3 feet into the ground to ensure the piers are secure after installation. Toss the excess dirt and soil aside. Continue digging until you have dug all of the holes.
Pour gravel into the holes and compact it down with a hand tamper. Fill the hole up halfway. Press the tamper over the surface of the gravel until it is flush and even throughout. Set the pre-formed concrete piers into the hole. Press them into place on top of the gravel. Repeat the process for all of the other holes.
Set a 4-by-4 post into each one of the concrete piers. Ensure the height of the posts matches up with the height of the deck that is already installed. Hammer in 2-by-8 joist boards to the side of the top of the posts. Run the boards across each post. Lay out deck boards on top of the joists and install them with a hammer and nails just like you would any other deck board.