A timber deck or balcony gets used for years without much thought. It holds the barbecue, the outdoor table and a crowd of guests on a warm evening. Yet it sits out in sun, rain and wind every day of the year. Over time that weather works on the timber, the fixings and the handrails.
Most problems start small and stay hidden for a while. A rusted bolt or a soft post base rarely looks dramatic. The good news is that a careful look once a year picks up most of them early. This guide covers what to check, the warning signs and when to call in a professional.
Why older decks and balconies deserve a closer look
Decks and balconies are common on Australian homes. Western Australia’s Consumer Protection notes that about six per cent of Australian houses have a timber balcony or deck. It also says around 2% of these, or roughly 12,000 properties, could cause potentially fatal injuries if they collapse or the railing fails.
The same page refers to Queensland Government figures of 20 deaths and hundreds of injuries from 2002 to 2012. These were linked to falls from balconies and decks or their collapse. Numbers like that are a good reason to treat the outdoor area as part of the structure of the house. It is not just furniture that lives outside.
How often to check
The Queensland Government recommends that you inspect your deck at least once a year. The Victorian Building Authority also suggests a visual check each year. Spring is a sensible time, before the deck gets heavy use over summer. A dry day makes it easier to see staining, cracks and soft timber.
Checking the frame and the posts
Start where the deck meets the ground. Timber posts should be a type suited to ground contact and properly treated. Look for wet rot, fungal growth or timber that feels spongy or fibrous. The Queensland Government advises fixing these problems straight away.
Steel posts need a different check. Look for rust or wear at the base, where water tends to collect. The Victorian Building Authority also says water should not pond at post bases, wall supports or on the deck surface. If it does, the drainage around the deck needs attention as well as the post itself.
Ground cover close to the deck can make a difference to how water sits around the posts. If you are planning new garden beds nearby, our guide to choosing soil, mulch or rocks for landscaping covers the options. Keep the area around post bases clear so you can see them. That makes the yearly check much quicker.
Bearers, joists and bracing
Next, look at the bearers and joists that carry the decking boards. Check for warping, cracking or any sign of decay. Bracing should be firm, with no cracks, warping or loose fixings. Look at how the deck is attached to the house too, since a balcony should be properly fixed to the building or have its beams running into it.
Fixings, bolts and brackets
Small parts hold the whole structure together. Check post brackets and other fixings for bending, stress, fractures or rust. Look closely at nuts, bolts, screws and nails as well. The Queensland Government advises replacing rusted fixings as soon as possible.
This is easy to overlook because a rusted bolt can still look solid. The Queensland Government warns that even small defects can compromise structural integrity and lead to a collapse. Coastal homes deserve extra care because salt air speeds up corrosion. Steel parts benefit from an anti rust coating and regular checks.
Handrails and balustrades
The balustrade is what stops people falling. Check handrails for rot, corrosion, looseness or instability. Look at the anchor points where the balustrade meets the deck, walls or posts. Lean on it gently and feel for any movement.
The Victorian Building Authority guide to balconies, decks and balustrades sets out some useful measurements. It says a balustrade should be at least one metre high, measured from the finished floor surface next to it. If tiles or paving were added after it was built, measure again. Openings should not let a 125 mm sphere pass through.
Where a fall could be more than 4 metres, the guide says horizontal parts between 150 mm and 760 mm above the floor should not allow climbing. Wire balustrades should be checked for loose cables and spacing. Toughened glass panels should be firmly attached, with no chips or cracks. Replace any cracked or broken glass straight away.
Glass is a popular choice around decks and pools. If you are weighing it up, our article on the pros and cons of glass pool fencing covers the trade offs. The same idea applies to a deck balustrade. Clear panels open up the view but still need regular checks of their fixings.
Warning signs that need action now
Some signs mean you should stop using the area until it has been checked. The Victorian Building Authority advises avoiding the area and restricting access if you are worried about its stability. Common warning signs include:
- timber that is soft, crumbling or growing fungus
- bolts, brackets or screws that are rusted, bent or loose
- a handrail or balustrade that moves when you lean on it
- cracked or chipped glass panels
- a concrete balcony that leans or has rust stains under it
- swaying or twisting when people walk across it
For concrete balconies, the Victorian Building Authority says the surface should be level. If it leans, there is a problem. Rust stains underneath can point to corroding steel reinforcement, which is serious. Cracking, flaking and spalling concrete also let moisture in.
Thinking about loads
A deck has to carry more than people. Large pot plants, outdoor furniture, spas and planter boxes all add weight. The Victorian Building Authority says designs must allow for the maximum number of people and the weight of items like these. If you plan to add something heavy, check the structure can take it first.
Planter boxes and garden features can also hold water against timber. Our article on landscape design features that need minimum maintenance has ideas for easy care outdoor areas. Choosing lighter, free draining options near the deck helps the timber last. It also cuts down on the jobs you need to do each year.
How long a deck should last
The Victorian Building Authority says a timber balcony should last at least 20 years when it is well maintained. A concrete balcony should last 40 to 50 years. Timber balustrades benefit from a weatherproof stain or paint, especially near the coast. Regular care is what gets a structure to those ages.
If your deck is near or past that age, a professional inspection is worth booking. A structural engineer or other suitably qualified building practitioner can find the full extent of any problem. In Victoria, the authority says a registered builder is needed for work over $10,000 in labour and materials. Rules differ between states, so check with your local building authority before starting repairs.
Buying or renting a home with a deck
Western Australia’s Consumer Protection suggests a building inspection before buying or renting out a property with a balcony, balustrade or raised deck. It names a structural engineer, registered builder or licensed pest inspector as suitable people. It also suggests asking the local council whether the structure was part of the original build. You can ask whether building approval is in place too.
Landlords in Western Australia must make sure their premises comply with building, health and safety laws. A deck or balcony is part of that. Buyers looking at homes with a pool should look at the whole outdoor area together. Our guide on how to choose the right swimming pool is a good place to start if a pool is part of the plan.
Frequently asked questions
How often should I check my deck?
The Queensland Government recommends an inspection at least once a year. The Victorian Building Authority also suggests a yearly visual check. Check again after a big storm or if you notice anything has changed.
What height should a deck balustrade be?
The Victorian Building Authority says at least one metre, measured from the finished floor next to it. If tiles or paving have been added since, measure again. Openings should not let a 125 mm sphere through.
Who should inspect an older deck?
A structural engineer or suitably qualified building practitioner can assess the full extent of any damage. Western Australia’s Consumer Protection also lists registered builders and licensed pest inspectors. Choose someone qualified for the type of structure you have.
This article is general information only. Building rules and approval requirements differ between states and territories and can change. Speak with your local building authority or a qualified building professional about your own deck or balcony.