On Page 2 I jumped the gun a bit in breaking out the tape measure and shovel. There's still a preliminary concern to consider before diving into the actual building of backyard decks. Consider that although the backyard deck doesn’t have to be an extension of the house, the majority of decks do abut against a house wall. But building such a deck can present a challenge. On this page I discuss an alternative that is easier -- freestanding decks.
Decks that rest smack up against a house usually derive structural support on that end by being attached to the house with bolts (or lag screws). But you can’t just blindly shove the bolt anywhere. Since you’re trying to achieve structural support, the wood in that area needs to be part of something substantial, something that is part of the underlying framework of the house: either the wall studs or floor joists. But you and your deck need to gain access to this solid wood – meaning you have to remove the siding of your house in that area (i.e., if your house is covered with clapboard, vinyl siding, aluminum siding, or beveled wood).
For the non-carpenter, removing your house’s siding is a pretty scary proposition. Let’s face it: Most of us take a “Leave well enough alone!” attitude towards our houses. We don’t want to screw up anything….
The good news is that there’s an alternative method, while still building the deck adjacent to your house: namely, the freestanding deck. Freestanding decks are a bit more work, because the house-end of the freestanding deck will have to rest on piers, in lieu of being connected to the house. That means extra digging for you, and additional concrete work. But for the sake of your peace of mind, this alternative may be worth the extra work.
But now that you know about freestanding decks, I’ll discuss the other method as well -– that of attaching the deck directly to the house for support -- just in case you’re feeling brave.
Carefully mark out where the header board should be attached to your house. The level at which the top of the header board rests should be the same as the level of your joists, atop which you will be attaching your decking. It is critical to ensure that the header is not only at the proper height, but also that it is level. The success of the whole project depends on this. The length of the header board equals the total length of the deck, minus 3”. Why minus 3”? Because the outermost joist on the left of the deck, as well as that on the right (as you face the house), should overlap the header board and be nailed to it. The joists will be, let’s say, 2 x 8s. As mentioned on the previous page, that means they’re actually 1 1/2” thick. Then multiply by 2.
Remove the siding where the header board must go. Tuck flashing up under the piece of siding that remains above this area. Roll the flashing down the side of the house, low enough that it will extend to a level below the bottom of your header board (the flashing will rest between the wall and the header board). Form a “lip” at the bottom, so that the water will be channeled away from the house. On the flashing, make marks where the bolts or lag screws must penetrate. Pre-drill the holes and caulk them.
Make corresponding marks on the header board, and make sure everything lines up. Now drill holes in the header board for the bolts or lag screws, and caulk the holes to further seal off your work from moisture problems. A slight space must also be left between the header and the wall, to allow rain to run freely down between the wall and the back of the header, averting rot. If you slide washers onto the lag screws or bolts in the back before securing the header, you’ll create the spacing you need. Tighten the bolts or lag screws.
That takes care of the house-end of the deck. On Page 4 we’ll proceed to the sides, as well as to the opposite end….