How to Frame a Deck Floor

Measure across the bottom of the exterior wall of the house where you want to connect the deck. Mark where on the wall you want the deck ends to hit. Measure up from these two marks to the deck’s height and mark it the wall.

Cut a piece of flashing and a 2-by-6-inch wood board to this length. Hold the flashing up against the wall so that the top lines up with the marks and place the board directly against the flashing, so that the top of the board also lines up with the marks. Placing a level on the board’s top ensures that the board and flashing are horizontal. Secure them to the wall with bolts spaced 6-inch around the board’s perimeter.

Place the measuring tape against the house where you made the first mark at the wall’s bottom and measure how far out from the house you want the deck’s outside edge to sit. Mark this spot with a large rock. Repeat the process for the second mark that you made against the base of the house.

Measure the distance from the ground to the top of the wood board you placed on the house to double-check the height. Add half again to this height, and then cut two 6-by-6-inch posts in this length. For a 5-foot deck, add another 2 ½ feet to get a 7 ½-foot post.

Dig holes with a post hole digger equal to the length that you added to the posts, such as the 2 ½ feet you added to the 7 ½-foot posts, where you placed the rocks on the ground. While digging, measure a few times ensuring that the holes sit the same distance from the house and the same distance apart as the length of the board attached to the house. Place a post in each hole, and then pour concrete into the ground around the post’s base, filling the hole to ground level.

Cut three 2-by-6-inch boards down for perimeter boards, one to the length of the distance between the two posts that you place and two to the length of the distance between each post and the board attached to the house. Secure the side boards between the board connected to the house and its opposite post, and the front board between the two front posts with screws after the concrete dries around the base of the posts.

Measure across each side board that connects to each end of the board attached to the house and the post opposite it. Mark these boards every 12 inches. Count the marks and cut this number of boards down to the same length as the board attached to the house.

Place the new boards at each set of marks between the two side boards. Secure the ends of each board by driving screws through the side board and into the ends of the crossing board, which becomes a floor joist. Cut the floorboards from 2-by-6-inch boards as well, and then lay them perpendicular to the joists, securing them to the joists with 4-inch nails.