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 years.) It is they whose boards warp and twist like actors in a horror film.
Alternatively, imagine a deck that you believed was sturdy, only to have your friend's heel slip through a decayed board during your Christmas celebration.
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, to be honest, made us want to cry for real. Fortunately, we don't have to learn these lessons 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, many do-it-yourselfers (as well as some dishonest contractors) neglect to thoroughly prepare the ground. 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. Out of the water, the deck starts to distort. Posts are slender. The entire structure becomes unsteady.
The answer isn’t difficult, 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 most exciting part of deck building, but it is the most important.
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:
When there is no slope drainage, water tends to pool on the surface instead of flowing off.
Decks built too close to the ground can lead to a moist environment and will be ready for wood rot production!
There is no consideration for where the water ends up—draining onto house foundations or inundating garden beds.
Insufficient height under the bed results in minimal air flow, a crucial factor during 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. Standing water anywhere poses a significant risk.
Spacing Issues That Cost You Later
This one is a little bit technical, but bear with me as it’s vital.
Timber moves. It swells in wet conditions and contracts when dry. Perth’s weather frequently experiences both extremes, often within the same week during spring.
Common spacing mistakes:
Boards are too closely spaced with no room for expansion – they buckle and warp during hot summer months.
Large gaps create trip hazards by allowing debris to fall through.
No openings around immovable objects, such as posts, planter boxes, and house walls.
Failing to space the boards apart as required by the manufacturer of your composite can lead to issues, and the recommended spacing may vary between brands.
A 4-6 mm gap between boards is ideal for hardwood timber decking. Refer to the manufacturer's instructions for composite materials. There must be space for everything.
Fastener Failures
What about the materials that hold your deck together?
This is such an easily avoidable mistake, but it constantly happens. We’ve pulled up decks when someone else used regular screws rather than deck screws or, even worse, nails that have popped up like tiny metal mushrooms after a few seasons.
Different materials need different fasteners. Use stainless steel or galvanised screws for wood decking because rust and corrosion are harmful. 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. It is 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 topic deserves its own category, as it relates to our living and working conditions.
It’s a tough climate for garden structures in Perth. Perth experiences scorching summers, salt-infused coastal air, and unpredictable winter storms.
Climate mistakes we see:
Planting timber species that are inappropriate for Perth; after six months of glory, they turn into an annoyance.
Failure to use climate-specific hardwoods such as Jarrah, Spotted Gum or Fijian Mahogany.
Pressure-treated lumber complies with ASTM F 366 and weathers over time, producing a final colour that may differ from what is depicted here, with the exception of composite materials like Trex, which are made especially to withstand fading, rotting, and warping.
The installation planning fails to take into account the local climatic conditions.
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
Many people tend to lose their enthusiasm at this point. The deck is up; it’s beautiful, and they can’t wait to use it.
But hold on.
Common finishing mistakes:
Avoid applying water seal to timber decks, as this can cause the wood to turn grey, weather, and crack.
Applying a sealant once a few years ago and neglecting water intrusion can lead to rot.
Failure to adhere to species-specific sealing protocols (e.g., some species require immediate sealing, while others require the wood to weather first) is a common issue.
Avoiding frequent resealing every 1-2 years, depending on how much sun your property receives, is crucial.
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 know what makes a good foundation with Perth soil, what materials are durable, and how to properly construct it.
Working with registered installers like Eco Carpentry for Trex composite decking provides you with a warranty that DIY installations cannot 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. Often, the repairs end up costing significantly more.
Is there a wavy deck with jacked-up footings? Excavating and rebuilding that frame is more involved than just picking up boards and placing new ones. 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 also corrected many mistakes made by others. And truthfully? We'd much rather do it correctly the first time.
Doing it correctly the first time benefits both you and your budget, allowing us to take pride in our work rather than feeling uncertain and anxious about uncovering issues beneath the surface.
You shouldn't worry about your deck; you should enjoy it. It should endure for many years, look lovely when you show it off to your friends, and withstand the weather in Perth. That's what you'll get if you don't make these mistakes, or even worse, if you try to manipulate people who already know how.
Ready to finally have your deck done right? Contact Eco Carpentry today for a professional quote.