Play with a full deck

By Alex Brooks

Before you bring out the hammer and nails, make sure you know the common pitfalls.

Here's the problem: if you stop 100 DIY-ers at random and ask them about their deck-building capabilities, most would think they could tackle the job well.
Yet even the keenest do-it-yourself-er can easily stuff up a deck.
Timber expert Stephen Larner - who runs Solutions in Timber - says the biggest mistake DIY deck builders make is not exploring the pitfalls.
"You have to make it comply with building codes, use the correct structural grade and durability timber, make sure the fixings are appropriate and the handrails are correct. That can be the hard part - doing all the research.
"There have been serious cases of decks collapsing and that can be devastating," Larner says.
Geoff Day from the Timber Development Association says the DIY-deck-builder must check the Australian Standard 1684 to work out the spans and height safety regulations that apply to the site. "The higher you build a deck off the ground, the more dangerous it is," Day says. "It has to be structurally sound."

Get independent quotes for someone to build you a deck - click here !

Read more about decks, DIY and renovation on Alex Brooks's blog - click here!

What can go wrong

The most common faults of DIY-ers are failing to attach the deck to the house correctly and failing to comply with building standards, according to licensed deck builder Greg Jacobs, who owns Pergola Land.
"People want the deck to open straight out from the living area, but there needs to be a small step down but not too much of a step or people don't go out there," he says. "I'm often called in to fix other people's mistakes."
Larner also points out that people's expectations of a deck are often too high.
"People expect a deck to behave to the same level and standard as a timber floor inside a house, but the deck is exposed to weather extremes from rain through to baking hot sun," he explains. "The one thing that damages timber the most is atmospheric change - as it shrinks and expands, it breaks down the surface of the timber."
And that causes splintering, which leads to one thing: deck death.
Once decking timber has splintered, Larner says there is little chance of salvaging the deck. Sometimes, a hardwood deck can be sanded back, the nails punched in and the timber reoiled - but in most cases, the decking will need to be relaid.
That's the other reason experts bang on about oiling or sealing outdoor decks regularly - it's easier to maintain the deck than to let it all go wrong.
Jacobs says he refuses to build with softwood decking, even though it is 30 per cent cheaper than class 1 or class 2 hardwoods.
"The softwoods crack and split more and don't look good three years later," he says. "You can't beat hardwoods. I always get the clients to go with hardwood decking, but to keep costs down we use the treated softwoods for the sub-structure."

Natural enemies

Day says most decks fail due to rot or termite damage. He suggests pouring concrete underneath the deck area and using steel stirrups to mount the timber supports off the ground.
Larner says the most common deck-building method is to create bearers and joists with decking boards laid over the top. The closer to the ground a deck is built, the more quickly it will deteriorate. "A deck should last 20 years if it's done properly," he says, pointing out that painting or coating the underside of timber decking before it is laid can extend its life.
He also believes that timber decks are not always suitable. "I wouldn't use timber on a north-facing side of a building - the beating sun can ruin a deck. I would use a fibre cement board in that case, which won't have the same appearance but would probably last longer," he says.
Day disagrees, and says there is no reason a timber deck could not be built in such conditions. Both experts say that building a pergola or shade cover over the deck will prolong its life.
"One of the things I've seen go wrong is not using the right nails. You need to use galvanised nails, but anywhere near the ocean you must use stainless steel fixings," he says. Jacobs says stainless steel fixings should also be used on decks near salt­water or chlorinated swimming pools. "I've seen decks less than two years old that have fallen apart near a pool because they used galvanised nails," he says.
If that seems too hard, call in a builder. "It costs about $300 a square metre, fully constructed and finished," Jacobs says.

Last the distance

• Building a deck is three or four times the cost of paving - so check whether it is the right solution.
• Most decks require council permission, but some councils allow decks smaller than 10 square metres to be constructed without approval.
• Use stainless steel nails if building a deck near the ocean or swimming pools
• Treated pine is 30 per cent cheaper than hardwood, but may not look as good once it is weathered.
• Timber inspector Stephen Larner says putting pot plants on decks is a no-no. "At least raise the pot plant off the deck so moisture can't collect underneath and lead to rot," he says. The nitrogen in plant foods can leach through the pots and break down the cellulose in the timber.
• Using a shade sail or pergola over a deck will prolong its life.
• Decking timber can be coated with paint, acrylic sealers or oils. It's important to follow the manufacturer's instructions and builder Greg Jacobs believes decks should be oiled every six months.
• Space the decking boards to allow for the timber to expand and moisture to drain.
• Jacobs suggests breaking free from rectangular and square decks by cutting a corner off or using a different shape. "Glass handrails look great if you have a bush view," he says.