Learn how to build a 10' x 12' deck on the back of your house using these simple steps. The size of the deck can be modified easily, but extending the length of the deck beyond 10' will require using 2x10 joists. The deck is designed to be built on a basically flat yard, that is level with the back of the house. If your yard slopes away from your back door, or your back door is elevated from your yard, please see my tutorial on installing posts and beams. Also see my handrail tutorial to discover how to build a railing for your deck.
Install Rim Joists. Mark out on the wall of your house where the deck will be. Remember that the 12 feet will be parallel with the house. Your back door should be located somewhere in this space. Lay 2 pier blocks directly against the house, spaced 8 inches in from each end of the 12 foot span marked on your wall. Place a 12 foot 2x8 on top of the pier blocks, inserted into the channel in the middle of the blocks. Check for level by placing your level on the top of the board. You may need to adjust the height of individual pier blocks by removing dirt from under them or by placing 2 or 4 inch concrete cap blocks under them. Once leveled, repeat the process by placing two more pier blocks 4 feet in from both end blocks. The 2x8 should rest solidly on all four pier blocks.
Repeat this process by measuring 10 feet back from the first rim joist and setting up the outer rim joist. Don't spend much time leveling this one just yet, just get the two outer piers in place and the 2x8 set and relatively level. Remove both rim joists.
Level Rim Joists. Nail a 10 foot joist between the rim joists on both ends of the rim joists. You should now have a 10 by 12 foot square. On the rim joist that is against the house, nail the 2x4 flush with the top of the 2x8, on the side closest to the house. Get a friend to help you and place the frame back on the pier blocks. Place your level on one of the newly installed joists and level the pier block on the outer rim joist. Repeat on the other side. Now you can go back and install the two inner pier blocks on the outer rim joist.
Install Joists. Lay out your joist spacing on the rim joists. Start on one side and make a mark every 16 inches measured from the outside of the rim joist. Mark an X the side of the mark that is closer to the side you are measuring from. This will help you remember where the board needs to go. Use the same layout on the other rim joist, making sure to measure from the same side. Now go back and use your square to draw a line at each mark to help install the 2x8's straight up and down. On the rim joist at the house, install joist hangers first, nailing them on flush with the line drawn, and the open space on the side of the X. Make sure the upper side of the joist hanger bottom is flush with the bottom of the rim joist. Slide the joist into the joist hanger and fasten the other end by driving nails through the outer rim joist into the joist.
Install Deck Boards. Start installing decking over the outer rim joist. The deck board should be flush with the outer edge of the rim joist and both side joists and run across the joists. Fasten the board down by installing two screws in each joist. Leave a ¼" gap between each deck board. The last deck board to go in should be the one next to the house. Leave a ½" gap between the house and the board. You will probably need to rip this board to the proper width.
Enjoy! Move your barbecue grill and some deck furniture onto your new deck and start enjoying it the day you finish up.