Use cinder blocks at this point to stand in temporarily for the wooden posts. That way, you can play around with the height and make sure you achieve the desired level (for the components at this end of the deck, see picture on right). But how do you check the level across such long distances? The answer is to run a long, straight board from the header to cinder blocks at the other end, and place your carpenter’s level upon this board. Once you’ve found the height that will give you the slope you need, you can just take note of the distance covered from the bottom of the cinder blocks to the top of the cinder blocks.
And how do you check the level in the other dimension – left to right? If you’ve been careful so far in installing your header board and side joists, you’ll now reap the rewards for your attention to detail. The side joists are your guides for keeping everything level left to right.
Using the measurements obtained from playing with the cinder blocks, you can determine the length the posts need to be.
But the posts alone do not span the distance from the tops of the piers to the bottom of the joists. On this end of the deck we’ll be using another piece of wood that will rest upon the posts, called a “girder.” The girder roughly corresponds to the header board at the other end, in the sense that it will serve as the support for the joists. But there’s an important difference. Joists will “hang” from the header board using joist hangers (which keeps them on the same level as the header board), but on the opposite end, joists will rest on top of the girder. The girder will be the length of the header board plus 3”. Deck builders often unite 2 boards to form a nice thick girder; for instance, two 2x10s to form, in essence, a 4x10.
Therefore it is the height of the joist plus the height of the girder plus the height of the post that the temporary cinder blocks spanned vertically. Or to put it another way: take the distance covered by the cinder blocks from top to bottom, subtract the height of the joist and the height of the girder from it, and you’ll have the height needed for the posts (see picture at upper right). Cut posts accordingly.
With both the posts and the girder cut to the right lengths, assemble them to form a unit, using post caps. Transfer this unit onto the concrete piers, using the post bases previously installed in the concrete to fasten the posts to the piers. Once the post-and-girder unit is secured to the piers, the top of the girder should meet the bottoms of the two outermost joists. If so, we’ve successfully completed the hard part of this project!
Although it’s still possible to screw something up later in the project, we’d probably be able to rectify it easily enough. It is in this sense that I referred on Page 1 to the steps presented in this article as the “essential” steps. If these steps are botched, you’ll probably have to start over from square one. But if you get through them successfully, the rest isn’t too bad.
That’s why I’ve focused on the project’s initial steps. Once completed, you’ll simply install the other joists. You’ll use fasteners called “seismic ties” to attach the joists to the girders. Let the joists at this end stick out beyond the girder willy-nilly, until they’re all in place. Then cut their ends off all at once, at some predetermined distance from the piers. These ends can be capped by a face board, if you prefer that look.
Your final major step is cutting the decking boards themselves and screwing them to the tops of the joists. Stagger the decking so that the seams don’t all line up; the deck will not only be more stable structurally this way, but will also look better. If your deck will be high off the ground, building codes dictate adding a railing. By the way, a popular alternative now to wood decking is composite decking (see picture on prior page). However, composite materials still aren't as strong as good old wood, so composite decking must be supported by wooden elements.
But believe me: After all we’ve been through up to this point, the deck railings will be a piece of cake.