Build a 50-Year Deck

22 Sep

Mum recently pointed me in the direction of Scotia Bank’s Eco Living blog and I found the following article.  Some good things to keep in mind IF and when we add a deck to the cottage.

cottage fall 2011 -110

Smart design can add durability and double the lifespan of your deck.

by Steve Maxwell

Most decks succumb to structural rot in 15 to 20 years, yet a handful of design features can easily double a deck’s lifespan, without significantly increasing the cost.

Promote water drainage:

Even rot-resistant wood isn’t rot-proof, but rot can’t happen if wood is dry most of the time. Minimize wood-to-wood contact areas that trap rot-inducing rainwater and insect droppings. Use solid support beams instead of the easier option of nailing three or four planks together, or use 1/2”-thick (12 mm) by 1 1/2”-wide (35 mm) pressure-treated plywood spacers to separate lumber as much as possible. Although plywood does contain small amounts of formaldehyde adhesive, Health Canada considers it entirely safe for use outdoors.

Separate deck board ends:

The ends of boards are among the most rot-prone areas in a deck, especially when they touch each other. Moisture trapped between board ends wicks deep into the wood through cellular passages, though this doesn’t have to happen. Install pairs of floor joists 1” apart in locations where board joints will occur. This allows the ends of boards to be spaced 1/8” to 1/4” apart for drainage, and you can fasten deck screws farther away from board ends so they’re less likely to cause cracks.

Use a hidden anchoring system:

Besides looking second-rate, exposed screws driven through the surface of boards allow water to penetrate the boards, promoting rot. The best fastener systems keep screws out of sight and also elevate boards slightly above floor joists, eliminating trapped water. If your boards will rest directly on floor joists, consider capping the joists with a self-sealing membrane before the boards go down, to keep the joists dry.

Build a weatherproof connection to your house:

If you’re planning to bolt a deck to your house, install whatever flashing and waterproofing features are necessary to keep water out. This is mostly about protecting your house frame, and in some cases an effective installation requires careful work with flashing and caulking. Building a completely separate foundation is sometimes easier because it leaves the weatherproof exterior of your home intact.

Create frost-proof foundations:

The easiest way to support a deck on the ground is with precast concrete deck blocks, but these are risky here in Canada: seasonal up-and-down movement of soil as it freezes and thaws can weaken and misalign even the best-built deck. Just a little cumulative movement each year adds up to a lot of displacement over 20 or 30 spring thaws. A frost-proof foundation built on concrete piers sunk three to four feet into the soil is a more reliable option. Wrap the outside of the cardboard form tubes with black polyethylene plastic before setting them into the ground and filling them with concrete. The plastic makes the surface too slippery for frozen soil to grab the surface of the piers and raise them.

Choose the greenest building materials for a healthy, long-lasting deck. Select a low-impact finish that keeps your deck looking great without eating up your summer to maintain.


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