What to Consider When Planning a Deck
1. Building permits are often required.
Permits are often required for decks and are obtained from the appropriate city agency. If a contractor is building the deck, the contractor should obtain the permit. The benefit of pulling a permit is that the overall project is cleared by zoning, wet lands (if required) and the building plan is reviewed by a certified building inspector.
2. Many factors determine deck size.
You should consider how your deck will be used – if a dining area is desired, a 12’ X 12’ sized area comfortably supports a 48” table with 4 chairs; a spa requires a 10’ X 10’ area for entry/exit and for cover storage; a cooking area needs a 5’X 8’ area for a normal gas grill; chaise lounge chairs also require about a 5’X 8’ area. Traffic patterns should be programmed at 4’ wide and used to link the various entertainment areas. Traffic area dimensions are also determined by entry onto the deck from the dwelling and from the deck onto the yard.
3. Proper footings are the base for a well-built deck.
This is not an area to skimp on. Depending on the City, footings can range from just a few inches to over 4’ deep. Building codes should be checked for local requirements. The spacing of footings along the girders (beams) is dependent upon the desired deck loading (the weight the deck will hold) and the size and type of materials used in the framing.
4. How well the deck frame is built determines the strength of your deck.
Minimum code requirements are 40 lbs per square foot. The span tables in most deck-building books provide the data for spacing the footings, girders, and joists based on the type and size of materials used and the PSF (pounds per square foot) desired. If using a composite decking, there may be specific joist spacing requirements to support that type of decking. If planning for a spa on the deck, then the deck loading factors need to be increased appropriately. Consulting a structural engineer can be very useful in this regard.
5. Using proper ledger attachments is vital to the deck’s structure.
The first choice is to always use a free-standing deck design rather than risk potential problems with attaching a ledger to the house. If the height of the deck requires a ledger then there are two major issues that need to be addressed. The first issue is attachment. How will it be attached to your house? Some zoning codes will have specific guidelines for this procedure. There are several different ways to attach the ledger to the house. Nails are not allowed in any method. The size of the deck determines the spacing and the number of bolts or lag screws to attach the ledger to the house. The second issue is flashing and potential water intrusion into the untreated framing lumber of the home. This is critical to prevent rotting to the home. With the new ACQ/CA wood, aluminum is not a suitable flashing material due to corrosion. Recommendations are now copper or vinyl.
6. How you install the decking and skirting impacts the durability of the deck.
Wood decking will expand and contract in reaction to moisture; composite decking will expand and contract in reaction to heat. Because the wood decking tends to “lift up” with swelling, some precautionary steps help minimize these issues. At any decking splice, double the joist so that each end of the decking board is sitting on 1 ½ inches of joist, pre-drill for screws within 3 inches of the end of the board. Also routing the ends will prevent the sharp edge when it rises a little bit. With composites, the gaping and spacing is critical for expansion, and also helps the deck ventilate and drain itself. The skirting should allow for ventilation beneath the deck. This helps keep the composite decking a bit cooler; and for both the wood and composite decks, helps to control the moisture beneath them which impacts mold/mildew growth. The chemicals used in the pressure treating process are now ACQ or AC (which no longer contain the arsenic that was in NCCA), but some of the lumber is no longer treated for ground contact. The tags on the lumber will state if suitable for ground contact use.
7. Choose your deck fasteners very carefully.
There are more and more choices for deck fasteners these days. The choice used to be just any nails, screws or hidden fasteners. The ACQ or AC, which replaced the CCA treatment in pressure treated lumber, is more corrosive and will impact the type of fasteners used. The standards for fastener compatibility have not been totally established, but electroplate and mechanical galvanized products are no longer recommended. Most suppliers of pressure treated lumber recommend the use of hot dipped galvanized or stainless steel fasteners. The key is to use a product that provides the desired holding power, the look you want, and the corrosion resistance required.
8. Railings and steps should be built with safety in mind.
Railing is required if decking is 30” above ground level. Normally this must meet guard rail requirements which are a minimum of 36” high, with no space more than 4” between spindles or balustrades. Post attachment is critical and if installing to a rim joist, the post will only be as sturdy as the rim joist. This means extra blocking may be needed to accommodate this requirement. Steps should have no or vary little variance for the rise/run between each step. There are several tables and rules of thumb presented in deck building books concerning the rise/run ratios. A hand rail is required for steps if there are 3 or more risers. The hand rail grip is to be no more than 2 5/8” in width.
9. Maintenance/upkeep is needed on all decks.
On wood decks, cleaning and sealing is a must to maintain the deck. Even composite decking needs cleaning to inhibit mold/mildew growth. Using a pressure washer is the standard mode for cleaning decks; however, care should be exercised to avoid damaging the decking material.
10. Take time to enjoy your deck.
Many people are so busy with their work day lives that they don’t take time to enjoy their decks. This could be the biggest mistake of all.