How to Install Beams for a Deck

After you set the posts in place, you are ready to install the beam. The beam runs parallel to the ledger board to hold the joists in place.

Difficulty: Moderately challenging

Instructions

Things You'll Need:

• Measuring Tapes
• Lumber
• Electric Variable-speed Drills (if Using Bolts)
• Galvanized Common Nails
• Hammers
• Hammers

1. Buy or build a beam of length suitable to the width to be spanned. 2-by-4s can be nailed together with plywood spaces to make the width of beam needed. (Check building codes in your area for the beam width required for your deck size.)

2. Turn the beam so that the crown side is up. (Most boards have a slight curve to them from one end to another, even when looking down the narrow edge. The side of the board that bows up in the middle is the crown side.) Placing the crown side up prevents sag later.

3. Set the beam on top of the posts and secure it to them. Temporarily secure prefabricated post caps to the tops of the posts until all final adjustments are made. (Post caps are prefabricated metal brackets that fit over the top of the post and use a U-shaped bracket to help hold the beam in place.)

4. Check that the beam's overhang is even on both ends.

5. Make the final permanent attachment of the beam to the post caps.

Tips & Warnings

• There should be a beam about every 8 to 10 feet along the length of the floor joists and a post about every 4 to 8 feet along the length of the beam.
• It's now considered common practice to use prefabricated "post caps" as they add strength and are easy to work with. Post caps are made from galvanized metal.
• To check frame to see whether it is square, measure diagonals. If the "box" frame is square, the diagonals will be equal.
• After all the beams are in place you can install the joists.
• If you are setting a beam in place above your head, always wear a hard hat and be sure your footing is secure.