Building a Deck: Overview
Planning a Deck
The key element in building a deck is the plan, which can serve as a guide throughout construction if it's been properly sized and drawn for existing codes and lumber tolerance.
Planning a deck doesn't require an architect or a drafting professional. A hand-drawn sketch will be sufficient for purchasing materials, getting a permit and guiding construction.
But there are many issues involved with building a deck. Problems can arise and a first-time deck builder should probably get professional help with the design since there's no substitute for a good plan. And the more inexperienced the builder, the better the plan should be.
Key Issues in Building a Deck
How will the deck lay out in relation to the house?
This is probably the most basic issue, since many factors will have to be considered and accommodated in the deck plan: the home's design, access in and out of the house (the project doubles in scope if a new door has to be put in), the space available outside, the grade of the yard (which impacts the deck's height) and existing trees or gardens.
How will it attach to the house?
Decks can be built free-standing. But for convenience most people do want them attached to the house. That raises questions about how the siding will be cut away at the point of attachment and whether there's solid house framing accessible at that point to properly support the deck.
How many footings and posts will be needed to support the deck and where will they go?
Footings and posts support the beams, which support the joists and the deck boards. The bigger the deck, the more footings you'll need.
What size beams will be needed for the spans between posts?
There are formulas to determine the sizes based on the spans. But the general rule is that the more footings used on a given span the smaller the beams need to be, so maximizing the footings will minimize the beams and vice-versa.
What size joists will be needed at what spacing to span between beams?
Joist size can vary from 2x6 to 2x10, and the spacing can be 12", 16" or 24" on center. Again there are formulas to determine the sizes and the spacing, but the bigger the deck, the bigger the joists and the closer you'll need to space them for proper support.
What size will the deck boards be?
The most popular sizes are 2x4, 2x6 and 5/4x6. The most obvious difference is in the board width: 2x4's produce more seams in a deck surface than 2x6's. You'll need more 2x4's to cover a surface, but it ends up being about the same amount of wood overall and about the same price.
Most municipalities will require a building permit for the construction of any deck, especially if it's to be attached to the house or it's more than 30 inches above ground.
We cannot stress enough the importance of consulting with your local building department about any home improvement project. Plus some homeowners insurance policies will not cover accidents involving construction that does not meet local codes.
There's a fee involved with most permit applications, but it's designed to cover the cost of a plan review before construction and the field inspections that'll be done after work begins. Inspections help insure that you're installing materials safely and according to code. Again, be sure to check with your building department to find out what inspections are required in your area. For example, in areas where frost footings are required, they'll probably want to inspect the depth of your footings before you fill them.
NOTE: The plan review and inspections are not designed to be a guarantee of the work but are done to improve the building safety in the community for the life of the structure.
(For the technically inclined, the American Wood Council offers a excellent 20-page document (“Prescriptive Residential Deck Construction Guide”) on their web site. It has guidelines for deck construction based on one of the most common building code books.)