Deck construction

Now that spring if officially upon us, we can at least start dreaming of warmer days and outdoor living. Whether you are looking to replace an old deck or design a new one, there are basic construction techniques homeowners should be aware of. The cost of material to build a deck can add up fast. Making sure your deck is properly constructed ensures it will last for years to come.

■ Footings – Decks should never be attached to your home unless proper footings are installed. Concrete landscaping blocks are not sufficient, ground heave from freeze/thaw cycles may cause the deck to shift over time and tear away from your home. To ensure your deck remains level over time, footings must be installed below the frost line. You can use traditional concrete footings (sonotubes) or there is a newer option available called screw piles. The advantage of screw piles is they can be installed very quickly with no cure time and minimal landscape disturbance. Whatever type of footing you use, make sure to lay out and space your footings correctly. Building code dictates the maximum distance allowed between footings, dependent on the size of joist material used.

■ Flashing – Not using proper flashing details where your deck attaches to your home is a common mistake that can lead to water damage and wood rot over time. Before attaching the ledger board flashing must be installed. Drip cap flashing at the top of the board and z-flashing at the bottom will prevent water from getting in behind siding. Installing J-channel or under sill trim along the borders will also help prevent the entry of water and give your deck a professionally finished look. Make sure to use a high-quality exterior caulk throughout the process to provide extra protection.

■ Ledger Board – Improperly installed ledger boards are a common cause of deck failure. The proper type of fastener to be used will depend on what the ledger board is being attached to. For example, lag bolts/screws are used when attaching the ledger to the home’s wood framing (i.e. rim joists). Through-bolts/sleeve anchors are required when attaching the ledger to concrete walls. Pre-drilling all holes is a good idea. Fastener height should be staggered to reduce chance of ledger splitting, and holes spaced according to code requirements. Galvanized or stainless steel fasteners, rated for pressure treated wood, should be used to prevent rust or corrosion. Ensure fasteners are long enough to penetrate securely into rim joists or concrete. Another tip is to ensure the deck is built two inches below the base of the door. This prevents snow melt from penetrating under door sills and damaging interior floors. The 2” gap also leaves room for doors to open freely if snow of ice accumulates during freeze/thaw events.

■ Decking – While pressure treated lumber is the standard, composite products are gaining in popularity. Composite decking is substantially more expensive but can last twice as long as a traditional wood deck. It is also virtually maintenance free, does not require stain or paint, and will not crack, warp or rot over time as fast as wood. To improve the lifespan of deck framing, waterproof tape should be applied over joists where decking can trap moisture, as well as between any joists that will be sandwiched together. When laying decking be sure to leave a minimum 1/8” gap between boards to allow water drainage. Using mitred corner joints to create a picture-frame look around the perimeter will protect end grains and is a great way to improve the visual appeal of your new deck.

Look for my article on the first Tuesday of every month in The News.

Feel free to call or email with any construction or maintenance topics you would like to see addressed. I can be reached by email at macgibcontracting@hotmail.com or by phone at 902-695-5919.