Great Deck Designs Require Planning
This is Part 7 of 9 in our Series on Restoring Wood Decks and Building New Wood Decks. Navigate to the first article: Restoring a Wood Deck
With your materials chosen, and your old deck destroyed, it is time to design your new deck. Deck design requires plenty of forethought to prevent it from looking like an afterthought.
Think about the shape, where people will gather, where there will be privacy or where people will be sheltered from the elements (wind or sun).
Include Special Elements in Deck Design Planning
Do you plan to install a hot tub on the deck? That will require extra support underneath, plus special wiring.
Will you be including any special "outdoor kitchen" elements that will require wiring or plumbing?
Decking laid on the diagonal always look classier than boards that run perpendicular to the joists, but you may need to run the joists narrower than 16 inches on center for a diagonal layout. For instance, Trex requires joists be 12 inches on center for diagonal boards. Stair risers for Trex stairs also have to be on 12-inch centers.
Where will you need railing? If the deck is more than 2 feet off the ground, it must have a rail, but perhaps you like the appearance of railing and want it even if the deck is less than 2 feet above the ground. Note: Railing is expensive, especially if it is the nice glass-panel or aluminum picket type, or something exotic like cable. Also, in visualizing railing, remember that it can have no more than 4 inches between balusters.
Deck Construction Permits
Most municipalities require a permit for a deck, even if it is replacing an old one. Proper permitting is important for a number of reasons: When you sell your house, you must disclose any work that was done without permit (if one was required); an inspector driving past your house easily can notice that you are working without a permit and slap a "stop-work" order on you; if you have an insurance claim for a reason involving a deck built without a permit, good luck collecting.
Required Deck Materials
Structural materials--posts, beams, and joists--must be pressure-treated wood. If designing your own deck, use the correct-sized lumber--the Web has span tables for joists and beams. Requirements could have changed since your old deck was built, so don't copy it. For instance, treated wood is weaker than Douglas fir and does not have the same load capability. Your building department will check the load requirements of your design, but it's better to have it right when you submit your drawings for a permit.
Know what kind of fasteners you will use on the boards. If you are using composite decking, you will want to use screws specially made for it. With wood decking, you have options of screws and spiral decking nails, both of which are expensive, but hold the decking very firmly. For most cases, 7d or 8d galvanized finish nails work fine. Countersink them, and the wood swells over the top so the nail head is barely visible.
You also can use hidden fasteners. These systems are more expensive than nails or screws and take more effort to install, but they do eliminate visible nails or screws in the deck surface.
Deck Shape: Don't Forget the Stairs!
Your deck must conform to the setback requirements for your zoning--if the setback for a house from the side of your lot is 10 feet, then the deck, including stairs, also cannot be any closer than 10 feet to your lot line. Improperly planned stairs can be a visual, and functional nightmare, jutting far out into a yard. A common stair pattern uses a 7-inch riser and a 10 ½-inch tread. So if your deck is 9 feet above the ground (108 inches) your stairs will run about 13 feet. You have to plan a way to accommodate that distance.
If your deck is going to have an impervious surface, it must slope away from your house. A 2-percent slope is standard (1/4 inch for every inch of run). Some builders will slope any deck, even if the decking is boards with gaps between; but this is not necessary if the ledger board has been properly flashed.
Thoughtful design is important. It will save you endless aggravation when it's time to build the deck.
Next, a look at construction tips for joists.
Next article: Install Deck Joists. Onto building a deck - the joy of joists.
Jim Mallery, a semi-retired journalist and onetime registered contractor, has extensive experience remodeling, repairing, and rebuilding homes.