5 things to consider before constructing your deck
So, you're thinking of hiring a contractor to build your deck. Before you begin, there are some things you’ll want to educate yourself about so you can make sure they're included in your deck, both for the safety of your family and guests and for the lifespan of the deck itself.
Below are five things to keep in mind as you begin the planning and construction of your deck.
1. Choose a knowledgeable contractor.
First, be sure to hire a knowledgeable contractor that has an intent to build your deck to meet or exceed the current local building codes for your address.
2. Prevent major failures.
In deck building, the two most common places a deck structurally fails, causing danger or harm, are at the deck-to-house connection and at the railing-to-deck connection. For proper deck design, the deck ledger board, the joist that is attached to your house, needs to be attached directly to the structure of your house.
Generally, if your deck is built at the same height as your interior house floor, you'll be connecting onto the rim-joist of the floor joists in your house. This means two things: first, that the siding behind the ledger needs to be removed, and second, that half-inch by four-and-a-half inch (or larger) galvanized lag bolts need to be installed in a staggered pattern, attaching the ledger to the house.
Be sure to use properly sized galvanized washers at each lag bolt and check local building codes for the appropriate lag spacing for your deck. Some jurisdictions now require hardware that attaches that deck joists to the house joists using galvanized brackets bolted to the joists, connecting the brackets together and preventing any separation of the deck from the house.
Likewise, the deck railings need to be designed and installed to prevent any railing separation from the deck and subsequent failure. There are a number of structurally sound ways to accomplish this connection in your deck building or deck retrofitting process.
The most effective way to accomplish this is to install the four-by-four railing posts on the inside of the rim-joist of the deck. Installed in this location with appropriate blocking of the posts, and the railing section between will provide a safe railing for many years of use.
Installing the deck posts with galvanized lag bolts is another good way to get the necessary structure. Be sure to add additional joist blocking behind each post and nail the blocking to the deck joists as well as the rim joist to achieve the strength you need for a safe deck rail.
3. Avoid water intrusion.
Preventing water intrusion at the house/deck connection is another critical element of a well-constructed deck. Proper flashing protects from any water intrusion into your house, basement or crawlspace. For correct flashing installation, the siding behind the deck ledger board needs to be removed and the flashing must be installed under the house siding and over the deck structure.
4. Ensure lateral support.
There are several necessary ingredients to provide lateral support of your deck. Blocking on top of the beam(s) and between the deck joists will prevent the joists from rolling. This is another necessary factor in a well-constructed deck.
For proper post/beam connection, wooden gussets attached to the beam and the posts are my choice. I find that metal post-caps retain moisture that leads to rot.
For angle bracing, a pressure treated board attached to the ledger board and installed at an angle across the bottoms of the deck joists will give your deck rigidity and eliminate any sway. Knee braces connecting the beams to the posts are often necessary when building a taller deck.
5. Check for proper bearing.
Proper bearing can be obtained from concrete piers with embedded galvanized post brackets. These need to be installed below your soil frost depth and sized appropriately for the dimensions and weight of your deck.
Arming yourself with some basic knowledge in these critical areas of a well-built deck will help you find a thorough, competent, knowledgeable contractor who can help you build the safe and well-designed deck you desire.