The Kiwi deck | Building and budget watch-outs
An important aspect of any Kiwi home is the outdoors. We can all relate to doors opening out onto an area where we can sit, relax, barbeque and entertain. The English have their patios, but us Kiwis, with our wooden floored houses raised above the ground, have a fondness for decks. A simple structure, a few bits of wood hanging off the house and supported on some posts, the deck is the quintessential home handyman/woman project.
But is it really? Here are a few things to take into consideration before tackling your very own deck build:
SCHEDULE 1 OF THE BUILDING ACT
A change to schedule 1 of the Building Act means that you can now build a deck 1.5m off the ground without a permit (the old rule was up to 1m).
This means that no part of the surface of the decking is allowed to be more than 1.5m off the ground. The change is good news for homeowners and DIYers, to the tune of $2,000 in savings to local body authorities, and another couple of grand not having to get plans drawn up by a local designer.
KEEPING TO CODE
The rule that hasn’t changed is that construction must be to code - the code being NZS 3604, 2011.
The floor of your house has to be designed to have a 1.5kPa rating, but a deck has to be designed to have a 2kPa rating, or a heavier load. That’s because more people are likely to congregate on a deck, so it needs to be able to handle it.
kPa RATING (kilopascal) is a measurement of pressure, or weight over a given area. E.g. 1.0 kPa is the pressure exerted by 100kg over a 1 square meter.
TIMBER TREATMENT
Timber treatment is all-important. Because a deck is external to the envelope of the house, the timber used to construct it must have undergone an H3 tanalising treatment. In comparison, any timber connecting the deck to the ground has to be H5 treated at a minimum.
FOUNDATIONS
Concrete foundations for piles are typically bigger than those holding your house up, and the concrete needs to be 20MPa minimum (costal zone concrete needs to be a minimum 25MPa).
MPa (megapascal) is a measure of the compressive strength of concrete. It outlines how much pressure can be applied to the concrete before it cracks or fails.
FIXINGS
Galvanised fixings have been proven to deteriorate from contact with the tanalising treatment in the timber when exposed to moisture, and even more so in a coastal zone with salt-laden moisture. Typically all fixings for decks (including bolts and nails) should be stainless steel 316.
I know that’s a lot to take in, and a bit technical, but information that I reckon you need to know.
BUDGET
The other thing to think about when building your deck is budget. Things like access to the house, slope of the land, and connection to the house can all affect the cost of your deck. Not to mention what sort of materials you use, what kind of balustrade, and whether there are stairs – or even a spa, if you’re lucky.
All that can make it tricky to figure out how much your dream deck will cost you.
But here’s a rough guide of what a few different budgets could get you (prices include builders, labour and materials):
$5,000 - 19mm pine decking, less than 1m above ground level, size 3m x 4m.
$10,000 - 19mm kwila (hardwood decking), over 1m above ground level, size 3m x 4m with a timber balustrade to 3 sides.
$12,000 - 19mm kwila decking, less than 1m above the ground level, size 6m x 6m.
$20,000 - 19mm kwila decking, over 1m above ground level, size 6m x 6m, with a glass balustrade to 3 sides.
$30,000 - 19mm kwila decking, second story, size 6m x 8m, with glass bulastrade and stairs to the ground with an aluminum and glass balustrade.
Of course every house and every deck is different, so it’s best to get a plan sorted and a quote or two from a professional before starting. And if you’re planning to do it yourself, make sure you have the skills and the tools before getting underway.
Best of luck,
Cheers, Cocksy.
We want to hear from you
GoodHome should be an enjoyable and worthwhile place to visit filled with information that helps you to be the smartest homeowner you can be. We want to hear about anything you found useful or anything you didn’t, and anything you want to see more of that would help make this the perfect site for you - email us at goodhome@bnz.co.nz
This article is intended as a general discussion only. BNZ recommends the recipient get independent advice. The views expressed are the writer’s own and do not necessarily represent those of BNZ or its related entities.
