How to Build an Addition on Pier & Beam

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.

Things You'll Need

  • Tape measure

  • Hammer

  • Stakes

  • Shovel

  • Gravel

  • Hand tamper

  • Pre-formed concrete piers

  • 4-by-4 posts

  • Hammer

  • Nails

  • 2-by-8 joists

  • Deck boards

Step 1

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.

Step 2

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.

Step 3

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.

Step 4

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.

Step 5

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.

References & Resources