How to Build a Deck: Part 3

The third video in our 5-part series covers framing the support structure for your deck.

Framing is the support structure of the deck and consists of posts, beams and joists.  This is where the fun begins and you can begin to see the results of your design and planning. As always, make sure you’ve consulted your local building codes before starting.

Construct the Beam

First, we need to construct the beam that will support the floor joists that will be attached to the ledger. Our deck beam will be cantilevered, meaning that the joists will extend past the beam. This results in a more esthetically pleasing look. The beam will consist of two 2 x 10’s screwed together. To support the beam, we use a metal post saddle to attach the beams to 4 x 4 posts.

Deck Structure

For the deck structure, we’re using 2 X 8 lumber. Most structural lumber has a natural bend, or crown. When selecting the boards for joists, sight down the edge to find the bend.  The up side is the crown. Setting joists with the crowns up builds extra strength into the deck. Our joists will be installed 16” on center, meaning it is 16 inches from the center of one joist to the center of the next.

Install Joist Hangers

We mark the joist locations on the ledger then install joist hangers. The joists will sit in these hangers. Be sure to use a nail in each of the joist hanger holes – the strength of the hanger connection depends on proper nailing. Place the joists into the hangers; the other end of the joist sits on top of the beam where it is screwed in place.

We install the joists full length and then cut them off in place. By using this method you’re ensured of a straight front edge of the deck, even if the house itself is not quite straight.

Install the Header

On the front of the deck, another 2 x 8 is attached to the ends of the joists. This is called the header. Cut and screw the header to the rim joist. To add strength to the deck, you can add one or two more layers of 2 x 8’s to the header.

Now we have the frame built for your deck, and we’re ready to begin laying the decking, which you’ll learn how to do in our next video.

Related Resources