Common Decking Mistakes and How to Avoid Them
Look, we've all seen them. (The ones that appear to have aged 20 years in a mere two.) They are the ones whose boards twist and warp like horror-movie actors.
Or worse – the deck you thought was holding up well until your mate’s heel went through a rotted board at your Christmas barbie.
Errors in deck installation are far too common and much more costly to fix later. Here’s the catch: many of these issues are entirely preventable if you’re aware of what to watch for.
Having spent countless years correcting other people’s deck disasters all over Perth, there isn’t much we haven’t seen.
And honestly? Some of them, we got to be honest, make us want to cry for real for real. But on the bright side, these lessons don’t have to be learnt the hard way.
The Foundation Fiasco
Here’s what may come as a surprise: the worst deck problems can begin even before you lay eyes on your first piece of wood.
Bad foundation work is the most common mistake we see. And it’s the most difficult to repair after the fact since, you know, it’s under your entire deck.
Well, a lot of DIY junkies (and some less-scrupulous contractors) don’t do the proper ground preparation. They might just stick the posts straight in the ground without any concrete footings, and if they do use footings, it’ll be ones that are far too shallow for our Perth changing soils. The deck begins to warp out of the water. Posts lean. The whole structure becomes unstable.
The answer isn’t hard, but it does take effort and time. Under the Australian Standard AS 2870-2011 (Residential Slabs and Footings), to reach stable ground levels generally in Perth soils, footings must be at least 600 mm deep.
They must be properly set into the concrete, and posts need to be treated and securely attached. It is not the exciting part of deck-building, but it is the most important part of deck-building.
Getting the Drainage All Wrong
Water and wood – they’re not best friends, are they? But time and again, so many deck builders seem to lose sight of this basic truth.
Common drainage mistakes we see:
No slope drainage, water pooling on the surface instead of running off.
Decks built too close to the ground can lead to a moist environment and will be ready for wood rot production!
No consideration for where water ends up – draining onto house foundations or inundating garden beds.
Insufficient height under the bed, with very little air flow (which is important in Perth’s humid winter months).
A deck that is built correctly should have a 1-2 degree angle from the house to assist in water runoff. Even composite decking such as Trex requires some drainage. Water standing anywhere is trouble on the lookout.
Spacing Issues That Cost You Later
This one is a little bit technical, but bear with me as it’s really important.
Timber moves. It swells in wet conditions and contracts when dry. Perth’s weather serves up both extremes, and often in the same week in spring.
Common spacing mistakes:
Boards too closely spaced with no room for expansion – buckle and warp during hot summer months.
Trip hazards with too-large gaps and space for debris to fall through.
No openings around immovable objects such as posts, planter boxes and house walls.
Not spacing them apart as required by the manufacturer of your composite (spacing will vary between brands).
For hardwood timber decking, a 4-6 mm gap between boards is the sweet spot. Refer to the manufacturer's instructions for composite materials. Everything needs room to breathe.
Fastener Failures
How about the stuff keeping your deck intact?
This is such an easily avoidable mistake but it happens all the time. We’ve pulled up decks when someone else used regular screws as opposed to deck screws or, even worse, nails that have popped up like tiny metal mushrooms after a few seasons.
Different materials need different fasteners. For timber decking, rust and food stains are a no-go area so go for stainless steel or galvanised screws. For composites such as Trex, hidden fastening systems that keep the decking surface blemish-free work incredibly well.
Placement matters too. Screws placed too close to the edge will split the board. Too far away from the edge and it will curl over time. And let’s not overlook the frame connections; joist hangers, structural brackets and bolts are not where you want to hold back on quality.
Ignoring Perth's Climate
This warrants a category of its own, because it pertains specifically to how and where we live and work.
It’s a tough climate for garden structures in Perth. Scorching summers, salt-infused coastal air and winter storms that are not to be underestimated.
Climate mistakes we see:
Planting timber species that shouldn’t be in Perth – they shine for six months, then go to buggery.
Failure to use climate-specific hardwoods such as Jarrah, Spotted Gum or Fijian Mahogany.
Except for composite materials such as Trex, which are specifically designed to resist fading, rotting and warping, pressure-treated lumber conforms to ASTM F 366 solitude and weathers over time, resulting in a final colour that may vary from what is shown here.
Not considering local climatic conditions in installation planning.
Material choice is crucial here. If you’re insisting on timber, choose hardwoods that can withstand our weather. Or, there is always composite decking, which has been engineered to stand up to a lifetime of harsh weather and virtually no maintenance.
The Finishing Touch That Gets Forgotten
This is where the zeal falls away for a lot of people. The deck is up; it’s beautiful and they can’t wait to use it.
But hold on.
Common finishing mistakes:
Never applying water seal to timber decks; timber turns grey, becomes weathered and cracks.
Seal it once a few years ago and ignore water entering; rot starts.
Failure to adhere to species-specific sealing protocols (e.g. some require immediate sealing; others need the wood weathered first).
Avoiding frequent resealing every 1-2 years (depending on how much sun your property gets).
For wood decking, finishing prevents the deck from ageing prematurely. Composite decking such as Trex requires little to no maintenance (other than the occasional hosing off). But if you have opted for timber, you’ve got to sign up to doing the same.
DIY Disasters and Why Professional Installation Matters
There’s a reason we see so many decks in distress.
Do-it-yourself deck projects sound quick and easy often enough and, happily, sometimes that’s all they take for a person to establish recreational space. But most folks have little experience with construction and no knowledge of building codes. Safety is why we have building codes; your deck must hold people, furniture and, while living in party central Perth, more guests than you intended to invite.
Minimum requirements for deck design and construction are prescribed in the National Construction Code (NCC), which applies to different parts of Australia and addresses matters such as structural integrity, load-bearing, and safety features.
These are not suggestions; they are requirements and standards that keep you and your family safe. These requirements are locally administered through the Building Commission WA, WA regions and have more localised conditions (Perth).
Deck contractors know how to prevent decking problems. We had our Trex deck built 10 years ago so I don't remember much… but have never had a problem. We know what makes a good foundation with Perth soil and what lasts as material, and we also understand here is how this needs to be built.
And by working with registered installers such as Eco Carpentry for Trex composite decking, you receive a warranty that DIY installations can’t offer. That’s no small thing when you’re dumping thousands into your outdoor space.
Getting It Right the First Time
The reality about deck installation mistakes is that their repair often costs more than the original job should have cost in the first place. Sometimes a lot more.
That wavy deck with the jacked-up footings? You’re not simply taking up boards and putting down new ones, but you’re having to excavate and reconstruct that frame, the whole nine yards. Those drainage issues are creating rot? The damage is spreading in ways you can’t see.
If you are considering timber decking or something more low-maintenance, like a composite deck, and whether it’s a sectioned-off area or an outdoor living space complete with screens and levels, getting the dimensions right is crucial.
Here at Eco Carpentry, we have designed hundreds of decks in Perth. We’ve corrected plenty that others got wrong, too. And honestly? We would much prefer to get it right the first time.
It’s better for you, better for your budget and we get the privilege to be proud of it rather than shaky, hoping we don’t find something that makes us feel embarrassed about what was under there.
You should like your deck, not worry about it. It should hold up for years, withstand the Perth weather and still be looking good when you’re flaunting it to your friends. That’s what not making these mistakes will get you — or better yet, manipulating individuals who already know how to.
Ready to finally have your deck done right? Contact Eco Carpentry today for a professional quote.