Deck Boards Lifting or Rotting?
Tell us the rough size of the deck, what the boards are made of and whether anything feels soft underfoot, and we will put you in touch with deck repairers servicing your area.
Typical Deck Repair Costs
The boards are the cheap part. What holds them up is where the money goes.
Deck Repair Service Cost WA 2026 - Complete Pricing Guide
A deck repair quote in Western Australia is really an answer to one question: is the problem the boards or the frame underneath them. Boards are consumable and cheap to swap at $45 to $110 a linear metre. Bearers, joists and posts are structure, and replacing them runs $110 to $280 a linear metre or $280 to $650 for a post and stirrup. Other 2026 rates are $25 to $60 a square metre to refix popped fixings, $25 to $55 a square metre to sand and re-oil, $180 to $450 a metre for balustrade work and $220 to $480 a square metre to rebuild a frame and relay boards. Two local conditions drive almost everything on this page. The first is termites, because Perth sits in a high pressure zone and a timber deck sitting close to sand is an invitation. The second is the sun, since ultraviolet levels here break down a coating faster than in the southern states and an unoiled jarrah deck greys and checks within a couple of summers. There is also a safety test worth doing today if your deck is raised. Where it is possible to fall a metre or more, a barrier is required, it has to be at least a metre high, and gaps in it must not let a 125 millimetre sphere through. Plenty of older Perth decks fail one of those three, usually because requirements tightened after they were built. Checking takes a tape measure and ten minutes, and the fix is cheap set against the consequence of getting it wrong.
At a Glance - Deck Repair Costs WA 2026
| Job | Cost | Time on Site | Structural? | Trade |
|---|---|---|---|---|
| Refix loose or popped fixings, per square metre | $25-$60 | 1 day | No | Handyman or carpenter |
| Sand and re-oil, per square metre | $25-$55 | 2-3 days | No | Painter or decking specialist |
| Replace deck boards, per linear metre | $45-$110 | 1-2 days | No | Carpenter |
| Replace a bearer or joist, per linear metre | $110-$280 | 1-3 days | Yes | Carpenter |
| Replace a post and stirrup | $280-$650 each | 1-2 days | Yes | Carpenter |
| Repair or replace a balustrade, per metre | $180-$450 | 1-3 days | Yes | Carpenter |
| Rebuild the frame and relay boards, per square metre | $220-$480 | 1-2 weeks | Yes | Carpenter or builder |
| Full deck replacement, per square metre | $320-$750 | 2-3 weeks | Yes | Builder |
Cost Depth: Boards Are Cheap, Frames Are Not
Every deck repair quote is answering the same question and the good ones say so in writing. Are the boards failing on their own, or are they telling you about the frame. A board that has cupped, split or weathered is a board, and swapping it at $45 to $110 a linear metre settles the matter. A board that has gone soft, that springs underfoot, or whose fixings keep working loose is usually reporting a wet or eaten joist.
That distinction explains the whole of the price range. Replacing twenty boards is a job of about two days. Lifting the same boards to replace two joists and a bearer, then relaying them, is a week and reaches $220 to $480 a square metre. Ask any quote to say what was probed and what was found, because a contractor who has only walked across the deck has priced the visible half of the problem.
Costs reflect timber species and availability, how much of the frame is affected, post and footing detail in sandy or limestone ground, deck height and whether a compliant barrier is required, termite damage, corrosion of fixings in coastal conditions, access beneath the deck, bushfire requirements where applicable, and location within Western Australia.
Deck Repair Costs in Western Australia for 2026
Deck repairs sort into three tiers and the tier decides the price far more than the size of the deck does. Surface work makes up the cheap tier of the three. Refixing fixings that have worked loose runs $25 to $60 a square metre. Sanding back and re-oiling is $25 to $55 a square metre and should be happening on a schedule, not once the timber has already greyed. Replacing individual boards comes in at $45 to $110 a linear metre, with the spread driven by species and whether a match can be found.
Structural work makes up the expensive tier of the three. A bearer or joist replaced runs $110 to $280 a linear metre. A post and its stirrup is $280 to $650. Balustrade repair or replacement is $180 to $450 a metre, and that is deck balustrade and handrail repair work. Rebuilding a frame and relaying the existing boards reaches $220 to $480 a square metre, and full replacement $320 to $750.
Western Australian decks fail in a pattern that reflects the ground and the climate. Perth metropolitan termite pressure is high, and a timber deck built low to sandy ground with a garden bed against it gives subterranean termites moisture, concealment and food in one place. The frame goes before the boards do, and the first sign is usually a board that springs underfoot rather than anything visible.
The sun does the other half of the damage. Ultraviolet levels here are high and summer surface temperatures on a west-facing deck are extreme, so a coating that would hold for three years in Hobart gives twelve to eighteen months on an exposed Perth deck. Jarrah left unoiled greys, checks and splinters quickly, and once the surface has cracked, water gets into the board. New construction is decking and the trade generally is carpentry services.
What Actually Fails on a Western Australian Deck
Decks fail from the bottom up and from the fixings out, which is why the visible surface is the least reliable guide to what is wrong. Coating failure comes first, and it counts as maintenance rather than damage. The oil or stain breaks down under ultraviolet, the surface greys, then the timber checks into fine surface cracks. At that point water gets into the board at every crack and the board starts to deteriorate. Caught at the greying stage it is a sand and re-oil. Left for several more years it becomes board replacement.
Fixing failure comes next and it tells you something. Nails or screws that lift, pop or spin are either corroded, or the timber they are holding has softened, or the board is moving more than the fixing can accommodate. A single popped nail means nothing at all. A pattern of loose fixings along one joist line is that joist reporting a problem.
Then come the failures in the structure itself. Rot in a bearer or joist where water has been sitting or where the timber meets a masonry wall without a gap. Termite damage, which leaves the surface intact and the inside hollow. Post and stirrup failure where the stirrup has corroded at the concrete line or the footing has moved in sand. And balustrade failure, which on an older deck is as often a compliance problem as a physical one.
The one that matters most is also the hardest to see. A deck more than a metre above ground with a failing balustrade, a soft joist near the edge or a corroded stirrup is a genuine injury risk, and these do not announce themselves. If your deck is raised and has not been looked at underneath in five years, that is the inspection to book, and building inspection or structural inspection will do it properly.
| Symptom | Likely Cause | Boards or Frame? | Repair Cost |
|---|---|---|---|
| Grey, dry surface with fine cracks | Coating broken down by ultraviolet | Boards, surface only | $25-$55 per sq m |
| Nails or screws lifting in one area | Corrosion, or softening timber below | Check the frame | $25-$60 per sq m |
| Board springs or flexes underfoot | Joist wet, rotted or eaten | Frame | $110-$280 per linear m |
| Board soft when probed with a screwdriver | Rot in the board itself | Boards | $45-$110 per linear m |
| Deck feels bouncy as a whole | Joist spacing or bearer span, or a failed post | Frame | $220-$480 per sq m |
| Rust staining at the base of a post | Stirrup corroded at the concrete line | Frame, structural | $280-$650 per post |
| Balustrade moves when pushed | Fixings, post rot, or never compliant | Structural and safety | $180-$450 per m |
| Hollow sound when a bearer is tapped | Termite damage with the surface intact | Frame, urgent | Inspect first |
A Twenty Minute Check You Can Do Yourself
Start with a screwdriver and probe the boards at the ends, near the fixings and anywhere that looks dark or stained. Sound timber resists; rotted timber takes the blade with little effort. Then walk the deck slowly and feel for any board that springs or any area that flexes as a whole, because that is the frame talking and not the boards. Mark whatever you find with chalk as you go.
Then get underneath if you safely can, with a torch. Look at where the bearers meet the posts, at the base of each post where the stirrup enters concrete, and at any point where timber touches masonry or sits close to soil. Finally push the balustrade firmly at the top rail, at several points along its length. Any movement at all on a raised deck needs attention before the deck is used again.
Probe with a screwdriver, feel for spring underfoot, inspect the posts and stirrups from below, and push the balustrade hard at the top rail.
The Timbers WA Decks Are Built From
Species decides the repair cost more than any other single factor, because matching an existing deck is often harder than the carpentry. Jarrah is the Western Australian timber and the state has a long relationship with it. It is a dense, durable local hardwood with excellent natural resistance to decay and insect attack, it weathers to a silver grey if left alone, and it is genuinely hard to work, so it needs pre-drilling and good tooling. Recycled and reclaimed jarrah from demolished houses supports a whole secondary market in Perth, and for a repair on an older jarrah deck, reclaimed boards often match better than new ones.
Merbau, sometimes sold as kwila, is the imported hardwood that dominated decking nationally for two decades and appears on a great many Perth decks built since the 1990s. It is durable and stable, and its one characteristic owners complain about is tannin bleed, which stains pale paving and render below a new deck for the first few months. Treated pine is the budget option, structurally fine when the treatment level matches the use, and it needs its cut ends treated at installation or they become the first failure point.
The repair implications differ considerably from species to species. Jarrah is extremely durable so a jarrah deck usually fails at the fixings, the coating or the frame long before the boards go. Merbau is stable but will eventually check and splinter without a coating. Treated pine rots where the treatment has been breached, particularly at cut ends and around fixings, so pine deck repairs cluster at the board ends and at the joist line.
For hardwood boards the practical advice is to buy a few spares at the time of any repair and store them under the house, because the colour and grade available in three years will not match what you buy today. A timber yard can usually advise on current availability, and Perth suppliers carry both new and reclaimed jarrah. Surface restoration of hardwood decking overlaps with floor sanding and polishing technique.
| Material | Durability | How It Fails | Repair Note |
|---|---|---|---|
| Jarrah, Western Australian hardwood | Very high | Fixings, coating, frame before boards | Reclaimed boards often match better than new |
| Merbau or kwila, imported hardwood | High | Checking and splintering without coating | Tannin bleed stains paving when new |
| Spotted gum or blackbutt | High | Surface checking, movement | Common on newer builds, good availability |
| Treated pine | Moderate | Rot at cut ends and fixings | Cut ends must be treated at installation |
| Cypress | Moderate to high | Surface weathering | Naturally termite resistant |
| Composite boards | High, no rot | Fading, scratching, thermal movement | Repair means matching a discontinued profile |
| Aluminium decking | Very high | Coating damage and galvanic issues | Uncommon, used on fire rated and coastal work |
Termites and the Perth Pressure Zone
Perth sits in one of the higher subterranean termite pressure areas in the country, and a timber deck is close to the ideal target. What termites need is moisture, concealment and cellulose, and a low deck over sandy ground supplies all three. They travel from the soil up inside a post or through a gap behind a bearer, and they eat the inside of the timber while leaving a thin outer shell intact. That is why a bearer can look entirely sound, take paint, and still be hollow enough to fail under load.
The invitations are all things an owner can remove. A deck frame sitting directly on or within a hundred millimetres of soil. A garden bed, mulch or lawn built up against the bearers. Reticulation throwing water onto the frame every morning. Timber offcuts, firewood or a pile of pavers stored underneath. And a deck built over a termite barrier in a way that bridges it, which a great many Perth decks do without anybody realising.
The signs are subtle and repay learning in detail. A hollow note when a bearer or post is tapped firmly. Mud or shelter tubes on a slab edge, a pier or the inside face of a post. A board or a joist that gives under a screwdriver with no visible rot. Swarming winged alates on a warm spring evening. Fine soil-like material spilling out of a crack. Any one of those justifies an inspection at $280 to $550 through termite inspection.
The repair is structural and it should not be rushed into without an inspection first, because replacing the eaten timber without dealing with the colony means doing it again. Allow $110 to $280 a linear metre for bearers and joists and $280 to $650 for a post, and treat the clearance and drainage problems in the same visit. Work on the structure itself falls under structural repairs.
Five Things to Fix Under Your Deck This Weekend
Clear everything stored underneath, especially timber offcuts, firewood, cardboard and pavers, because each of those is either food or cover. Pull garden beds, mulch and built-up soil back from the bearers so there is a clear gap and the frame can dry. Adjust or move any reticulation head that throws water onto the deck frame, since that single change removes the moisture termites need. Then look at the clearance and the barriers. The frame should sit clear of the soil instead of in it, and if your house has a physical or chemical termite management system at the slab edge, check whether the deck has been built across it in a way that bridges it. Finally photograph the underside while you are there, because that record is genuinely useful at the next inspection.
Clear the storage, pull the garden back, redirect the reticulation, restore the clearance, and check whether the deck bridges the termite barrier.
Posts, Stirrups and Footings in Sand
Deck posts fail differently in Western Australia and the reason is what they are standing in. A deck post should sit on a galvanised stirrup set into a concrete footing, with the timber held clear of the concrete so water cannot wick up into the end grain. In Perth sand the footing has to do all the work, because sand provides very little lateral support on its own, so the concrete pad needs adequate depth and diameter. A post concreted directly into the ground without a stirrup is the older detail, and that is the one that rots at the ground line every time.
Limestone under the sand creates the opposite problem. Where a post hole hits cap rock at a few hundred millimetres, the footing ends up shallow and sitting on rock, which is a sound arrangement if the post is mechanically anchored into the limestone with a chemical anchor system from Ramset or Hilti, and a poor one if somebody simply poured a pad on top of the rock. Ask what is under a post before agreeing a price to reset it.
Stirrup corrosion is the most common structural failure on an older Perth deck. The stirrup is galvanised steel and it corrodes at the line where it enters the concrete, because that is where moisture and oxygen meet and where salt collects. The post above can be sound jarrah throughout and the deck can still be unsafe. This is one to look at specifically, with a torch, from underneath.
Replacing a post and stirrup runs $280 to $650 and the work involves propping the deck, cutting out the old post, breaking out and repouring the footing if it has failed, setting a new stirrup and fitting the post. On a coastal block specify a heavier galvanised or stainless stirrup than the original, because the original specification is what failed. Excavation of new footings is post hole digging and concrete work is concreting services.
Bearers, Joists and the Frame Under the Boards
The frame is where deck repair money actually goes, and it is the half of the deck nobody photographs. Bearers run from post to post and carry the joists. Joists run across the bearers at set centres and carry the boards. Both are sized by span tables in the residential timber framing standard, and both fail in the same three ways: rot where water sits or where they meet masonry without a gap, termite attack from below, and splitting or crushing at the connections.
The connection points deserve special attention in Western Australia. Where a bearer or a ledger is bolted to a double brick wall, the detail must hold the timber clear of the masonry with a flashing above it, because brickwork holds moisture and timber hard against it will rot. A ledger bolted flat to a rendered wall with no gap and no flashing is a very common older detail, and it is where a deck most often fails at the house end, which is also the most dangerous place for it to fail.
Diagnosis means probing the timber, not looking at it. A screwdriver pushed firmly into a bearer at the post, at the wall connection and anywhere stained will find soft timber immediately. Tapping along the length will find the hollow note of termite damage. Sighting along the underside will reveal any deflection. None of that takes long and all of it has to happen before a quote means anything.
Frame members come in at $110 to $280 a linear metre, and the variation is access. A joist reachable from below on a raised deck is straightforward. The same joist on a deck 300 millimetres off the ground means lifting boards to work from above, which adds board handling and the risk of breaking boards that then need matching. Where more than about a third of the frame is affected, a rebuild at $220 to $480 a square metre is usually better value than chasing it piece by piece.
How to Probe a Deck Frame Properly
Use a long screwdriver or an awl, not your fingers, and push firmly instead of tapping. Sound hardwood will barely take a mark from it. Rotted timber takes the blade 10 or 20 millimetres with little resistance, and you will know the difference immediately once you have felt both. Work along each bearer and joist and test at the places water collects: the post connection, the wall connection, under any gap between boards and anywhere stained dark.
Then tap with a hammer handle and listen. A solid note means the timber beneath is solid. A hollow or papery note with a sound surface is the signature of termite damage, and that needs an inspection before anything is replaced. Mark everything you find with chalk and photograph it, because that record is what turns a vague quote into a specific one.
Push firmly with a screwdriver at every connection and stain, tap and listen for a hollow note, then chalk and photograph what you find.
Board Replacement and Fixings
Board work shows more than anything else on a deck repair, and getting it wrong is something you then look at every day. Boards come in at $45 to $110 a linear metre and the job itself is straightforward: the old board comes out, the joist tops are checked and cleaned, and a new board goes in with a consistent gap. The gap between boards matters more than people think. Hardwood boards move with moisture, so too tight and they bind and cup, too wide and the deck looks wrong and small items fall through. Matching the existing gap is part of the job.
Colour is the problem nobody warns owners about. A new board in an eight year old jarrah or merbau deck will be obviously different for the first season, and oiling will not hide it. The options are to accept it and wait, to source reclaimed timber of similar age, to sand and re-oil the whole deck after the repair so everything starts from the same surface, or to place new boards where they are least noticed. Sanding the whole deck is usually the answer that satisfies people.
Fixings are worth upgrading at the same time. Older decks used plain galvanised nails, which lift over time as boards move and corrode on coastal blocks. Stainless or heavily galvanised decking screws hold far better, can be removed without damaging the board, and do not lift. Hidden fastener systems are available but make future board replacement harder, which is a genuine trade-off on a deck you intend to keep.
One detail applies specifically to dense hardwood boards. Jarrah and merbau both need pre-drilling, and a screw driven into dense hardwood without a pilot hole will split the board or snap. A contractor who is pre-drilling is doing it right even though it looks slow. Fixings that have been driven without pre-drilling show up later as splits radiating from the screw head.
Balustrades, Barriers and the One Metre Rule
What follows has a safety consequence rather than a cost one, and the numbers are specific enough to check with a tape measure this afternoon. A barrier is required wherever it is possible to fall one metre or more from a trafficable surface to the level beneath. Where one is required, the barrier must be not less than one metre above the deck floor. On stairs the handrail or barrier must be not less than 865 millimetres above the nosings of the treads. Openings in a barrier must not permit a 125 millimetre sphere to pass through, and where a barrier is attached to a vertical face, the gap between the barrier and the floor edge must not exceed 40 millimetres.
There is a further rule for higher decks. Where the fall exceeds four metres, any horizontal element within the barrier between 150 millimetres and 760 millimetres above the floor must give a child nothing to climb on, which rules out mid-rails, horizontal wires and ledges in that band. Vertical balusters and glass panels remain acceptable under that rule. That catches a lot of second storey balconies with horizontal wire balustrades installed for the look.
Older Perth decks fail these tests regularly, and not through neglect. Requirements have tightened over time, a deck built to the rules of 1995 is not necessarily compliant now, and a deck built without a permit may never have been checked against anything. The three to measure yourself are the height above the deck, the gap test with a 125 millimetre object, and whether the whole assembly moves when pushed hard at the top rail. Repair or replacement runs $180 to $450 a metre depending on material and whether the posts are sound. Where a post has rotted at its base the post is the job and the rail is incidental. Glass panel balustrades have their own hardware and that is glass balustrade installation and repairs territory, while new work generally is balustrade installation.
| Requirement | Figure | Applies When | Easy to Check? |
|---|---|---|---|
| Barrier required | Where a fall of 1 m or more is possible | Any trafficable deck or balcony | Yes, measure the drop |
| Minimum barrier height | 1 m above the deck floor | Wherever a barrier is required | Yes, with a tape |
| Minimum height on stairs | 865 mm above the tread nosings | Stairs and landings | Yes, measure from the nosing |
| Maximum opening | Must not pass a 125 mm sphere | All barriers | Yes, with a 125 mm object |
| Gap to the floor edge | 40 mm maximum | Barrier fixed to a vertical face | Yes, with a tape |
| Non-climbable band | No climbable horizontal element 150 mm to 760 mm above the floor | Where the fall exceeds 4 m | Yes, look for mid-rails and wires |
| Structural adequacy | Must resist imposed loads | All barriers | No, needs assessment |
Three Measurements and a Push
Measure the drop from the deck surface to the ground or the level below. At one metre or more a barrier is required, and plenty of decks sit just over that line without one. Then measure the barrier height from the deck floor to the top of the rail: it needs to be at least one metre. On any stairs, measure from the nosing of a tread to the top of the handrail, which needs at least 865 millimetres.
Then test the gaps with something 125 millimetres across, which is roughly the width of a standard brick on its end. Nothing in the barrier should let it pass, including the gap at the bottom. Finally push the top rail hard, at several points along its length and at every post. Any flex, creak or movement on a raised deck is a reason to keep people off it until it has been looked at.
The drop, the barrier height, the stair handrail height, the 125 millimetre gap test, and a firm push at every post.
Stairs and Handrails
Deck stairs take more punishment than the deck does and they are where most deck injuries actually happen. Treads wear and cup, stringers rot at the bottom where they meet the ground or a paved area, and the fixings at the top connection work loose from repeated loading. The bottom of a timber stringer sitting directly on soil or on paving that holds water is the single most common rot point on any deck, because it combines end grain, moisture and no air movement. Dimensional consistency is where the safety issue sits. Risers and goings have to be consistent within a flight, because people climb stairs by rhythm and not by looking, and a single tread that differs by more than a few millimetres is a trip. On a deck where somebody has replaced one or two treads with timber of a different thickness, that inconsistency has been built in, and correcting it matters even though the stairs feel usable.
Handrails on stairs must be not less than 865 millimetres above the nosings of the treads, and the same 125 millimetre opening rule applies to any barrier alongside. A graspable handrail matters as much as the height, since a wide flat top rail is hard to hold and gives nothing to grab if somebody slips. Repairs run from $180 to $650 for individual treads and fixings up to $1,200 to $3,500 for a full flight rebuilt with new stringers, depending on width and rise. Where the stringer base is the problem, the repair should include getting it clear of the ground on a concrete pad or a galvanised shoe, because replacing it in the same detail reproduces the failure. Dedicated work sits under external stair and handrail repairs.
Oils, Stains and the Western Australian Sun
Coating a deck in this climate is maintenance on a schedule, and the schedule is shorter here than almost anywhere else in the country. Ultraviolet breaks down the lignin at the timber surface, which is what turns an oiled jarrah deck grey. Once the surface greys it begins to check into fine cracks, and water enters at every crack. Perth ultraviolet levels are high and a west or north facing deck reaches summer surface temperatures that no coating enjoys, so a decking oil gives 12 to 18 months on an exposed deck and perhaps two to three years on a shaded one.
Three product families do the job in different ways. Penetrating oils soak into the timber, keep the natural look, weather by fading instead of peeling and are easy to re-apply over themselves, which makes them the usual choice. Decking stains add pigment, which blocks more ultraviolet and lasts longer, at the cost of looking less like bare timber. Film-forming coatings and decking paints last longest on paper and are the worst choice on a trafficked deck, because when they fail they peel and the only way back is a full sand.
Preparation is what decides the result here. A deck that has greyed needs the degraded surface removed, either by sanding or with a timber cleaner and brightener, because oil applied over a grey weathered surface sits on dead fibre and lifts. Sanding and re-oiling runs $25 to $55 a square metre and is the reset that makes subsequent maintenance coats work. Cabot, Intergrain, Feast Watson and Sikkens products are all widely available through Perth outlets.
One practical warning belongs here about pressure washing. A high pressure washer on a timber deck will raise the grain, erode the softer early wood and leave a furry surface that then needs sanding, and on an older board it will take material off. Use a low pressure wash with a cleaner instead, and save the pressure for concrete. Coating work falls under exterior painting and painting services.
| Coating Type | Life on an Exposed Perth Deck | How It Fails | Recoat Process |
|---|---|---|---|
| Penetrating decking oil | 12-18 months | Fades and greys | Clean and re-apply, no sanding |
| Penetrating oil, shaded deck | 2-3 years | Fades slowly | Clean and re-apply |
| Pigmented decking stain | 2-3 years | Fades, some surface wear | Clean and re-apply |
| Water-based decking stain | 18 months to 2 years | Fades, can lift at wear points | Clean, spot sand, re-apply |
| Film-forming coating or decking paint | 3-5 years | Peels and flakes | Full sand back, worst case |
| Nothing, left to weather | Not applicable | Greys, checks, splinters | Full sand and oil to reset |
| Composite boards | No coating needed | Fades in the first year then stabilises | Clean only |
A Realistic Coating Schedule for a Perth Deck
Treat an exposed deck as an annual job and a shaded one as every second or third year, and do it in autumn or early spring instead of the middle of summer, because a hot board will flash off the oil before it penetrates. The test for whether it is due is simple: splash water on the deck, and if it soaks straight in and darkens the timber, the coating has gone. Keep to the same product family so maintenance coats go over what is already there without a full sand. Switching from an oil to a film-forming coating, or the reverse, generally means stripping back first. And do the reset once instead of fighting it: a deck that has greyed badly needs the full sand and oil at $25 to $55 a square metre, and everything after that is a clean and a recoat.
Annually on an exposed deck, autumn or early spring, test with a splash of water, and stay in the same product family.
Salt, Coastal Decks and Corrosion
On a coastal Western Australian block the timber usually outlasts the metal holding it together, and that reverses the usual order of deck repairs. Salt aerosol carried inland on the afternoon sea breeze settles on every surface and holds moisture against metal long after rain has stopped. On a deck that means nails and screws corroding in the boards, joist hangers and bracket plates rusting at their fixings, bolts at the bearer connections losing section, and post stirrups corroding at the concrete line. The jarrah can be sound and the deck can still be unsafe.
Corrosion in fixings also damages the timber around them. Iron staining spreads as a black halo in hardwood, particularly in jarrah and merbau where the tannins react with the iron, and the timber at the fixing softens. That is why an old deck often has sound boards with soft, stained holes, and why simply driving a new screw into the same hole achieves nothing.
Specification is very nearly the whole of the answer. Close to the surf, within a couple of hundred metres, stainless fixings and stainless or heavy galvanised brackets are the sensible minimum, and even stainless will tea-stain, which is cosmetic. Further inland, a heavy hot-dip galvanised specification is adequate. Mixing metals causes its own problems, so a galvanised bracket with stainless screws through it, or copper in contact with galvanised steel, sets up galvanic corrosion.
Rinsing costs nothing at all and it genuinely works. Hosing a coastal deck and its fixings down two or three times a year with fresh water removes the salt before it does its work, and it matters most on the parts rain does not reach, which means under the deck, at the bearer connections and on the sheltered side of posts. Work health and safety requirements for contractors working at height on a raised deck sit with WorkSafe Western Australia.
| Location | Exposure | Minimum Fixing Specification | Expected Life |
|---|---|---|---|
| Within 100 m of breaking surf | Severe marine | Stainless, grade 316 | 15-25 years, rinse regularly |
| 100 m to 1 km from the coast | Marine | Stainless or heavy hot-dip galvanised | 20-30 years |
| 1 km to 5 km from the coast | Moderate marine | Heavy hot-dip galvanised | 25-35 years |
| Perth inland suburbs | Low | Hot-dip galvanised | 30-40 years |
| Perth hills | Low, higher moisture | Hot-dip galvanised | 30-40 years |
| Wheatbelt and Goldfields | Low, saline soils near salt lakes | Hot-dip galvanised minimum | 30-40 years |
| Pilbara and Kimberley coast | Severe marine | Stainless, grade 316 | 15-25 years |
| Any deck over or beside a pool | Chlorine or salt chlorination | Stainless, grade 316 | 15-25 years |
Composite Decking Repairs
Composite boards have taken a large share of the Perth market over the past decade and they bring a different repair problem rather than no repair problem. The material is a wood-flour and polymer composite, either uncapped or with a bonded polymer cap, and the things it does well are real enough. It does not rot, it does not need oiling, termites have no interest in it, and it does not splinter. Brands including Modwood, Ekodeck, Trex and NewTechWood are all sold into the Perth market and most carry long warranties.
What goes wrong with them is different from timber. Composite boards expand and contract with temperature far more than timber does, so a deck installed without the specified end gaps in a Perth summer will buckle, and the first hot spell after installation is when it shows. Dark boards get extremely hot underfoot in this climate, hot enough to be unpleasant barefoot. Scratches from furniture and dog claws cannot be sanded out on a capped board, because sanding removes the cap. And early uncapped products faded and stained considerably.
That turns composite repairs into a matching exercise. Composite ranges, colours and board profiles change frequently, so a damaged board on a seven year old deck may have no current equivalent. The practical approaches are to harvest a board from a concealed area such as under a bench or behind a planter, to accept a near match placed where it is least visible, or to replace a whole section to a natural break. The frame underneath is still timber or steel on almost every composite deck, so everything in this page about bearers, joists, posts, stirrups and termites applies in full. A composite deck is not a maintenance free deck, it is a deck whose maintenance has moved from the boards to the frame, and the frame is the part that carries people. Inspection still matters, and structural inspection is how to get it done.
Building Permits and the 500 Millimetre Threshold
Decks sit in the part of Western Australian building regulation where the answer depends on your local government, so the general rule is a starting point and not the final word. The common threshold across WA local governments is height. A deck more than 500 millimetres above natural ground level generally requires a building permit, while one at or below 500 millimetres often does not, provided nothing else triggers approval. The City of Joondalup, for example, requires a building permit where a deck is higher than 500 millimetres. Other councils apply the same figure, but the detail varies, so confirm with yours rather than relying on a neighbour or a contractor.
Planning approval runs separately from the building permit and is driven by the Residential Design Codes. Where a deck is 500 millimetres or more above natural ground level, planning approval is generally needed unless it complies with the setback and privacy screen provisions. On an R20 coded lot the minimum side or rear setback is typically one metre, rising to 1.5 metres for longer decks without privacy screens, and privacy screens where required are typically a minimum of 1.6 metres high within 7.5 metres of a boundary.
That matters for a repair in one specific circumstance. Like-for-like repair of an existing deck is maintenance and does not need a permit. Rebuilding a deck, raising it, extending it or changing its footprint generally does, and if the original deck was built without a permit the rebuild is the moment that comes to light. It is better to find that out before the work than during a sale.
Where you do not know whether your deck was approved, your local government will have the records and will usually tell you over the counter. A deck that was never approved is not automatically a problem, but it is something a buyer will ask about, and resolving it is far easier while the house is not on the market. Building and Energy sets out the current building requirements, at the Government of Western Australia, and the construction provisions behind them by the Australian Building Codes Board.
Working Out Whether Your Deck Work Needs Approval
Measure the height from natural ground level to the deck surface. Above 500 millimetres, expect to need a building permit, and in most cases planning approval as well unless the deck complies with the setback and privacy screen provisions of the R-Codes. At or below 500 millimetres, many councils require neither, though the detail varies between local governments so confirm it rather than assuming.
Then work out which kind of job you have. Repairing or replacing boards, joists, bearers, posts or a balustrade in the same position and the same configuration is maintenance. Raising the deck, extending it, changing its footprint or adding a roof is new work. If the original deck has no approval on record, raise it with the council yourself before a rebuild, because it is far cheaper to resolve than to discover during a sale.
Measure from natural ground level, 500 millimetres is the usual trigger, like-for-like repair is maintenance, and check the original approval before any rebuild.
Who Can Do the Work and WA Thresholds
Carpentry is not a separately licensed trade in Western Australia, so the protection on a deck repair comes from the contract and the thresholds rather than from a licence number. Oversight of building work here sits with Building and Energy, a regulator inside the Department of Local Government, Industry Regulation and Safety whose two statutory officers are the Building Commissioner and the Director of Energy Safety. Builder registration is what bites above a value threshold, and some contractors still name a body that has been superseded, so run any registration number past the current register yourself.
Three numbers shape the paperwork on deck work. The written home building contract requirement covers fixed-price residential work from $7,500 up to $500,000. Home indemnity insurance kicks in once permitted work passes $20,000, and its deposit-loss cover reaches $40,000. No deposit may exceed 6.5 per cent of the contract price. Those three figures are specific to Western Australia.
Most deck repairs fall below $7,500 and can therefore be done by a carpenter or a competent handyman without builder registration. Get the scope in writing regardless, naming which boards, joists and bearers are being replaced, the timber species and grade, the fixing specification, and what rate applies if more rot is found once boards come up. A full deck rebuild can cross $7,500 and sometimes $20,000, which brings registration and insurance into play.
Two things to be clear about on a raised deck. Structural adequacy is not a matter of opinion, so where bearers, joists, posts or a barrier are being replaced, spans and fixings should follow the residential timber framing standard or an engineer. And statutory consumer guarantees apply to the workmanship regardless of what any warranty document says, which are administered by the Australian Competition and Consumer Commission. Building and construction is one of the areas the State Administrative Tribunal hears, and the regulations are published at Western Australian Legislation and the standards through Standards Australia.
Perth Metropolitan Pricing
Metropolitan deck pricing is competitive on surface work and much more variable on structural work, which tells you where to get more than one quote. Sanding and oiling is a commodity service with plenty of operators, and the rate is fairly consistent at $25 to $55 a square metre. Board replacement is competitively priced across the metro area. Frame and post work is where quotes diverge, because it requires a carpenter willing to prop a deck and take responsibility for structure, and fewer contractors want that job than want the sanding.
The metro area divides into three sub-markets that behave differently. Fixing corrosion runs fastest along the coast, from Fremantle north through Scarborough and Hillarys, so stainless specification is routine and stirrup replacement is common. The inner and older suburbs carry jarrah decks, often with a ledger bolted to a double brick wall and often with pre-1990 compliance, which is the most involved work. Newer merbau, treated pine and composite decks fill the northern and southern corridors, where the failures are coatings, fixings and termite pressure on low decks over sand.
Access under the deck is the cost variable that nobody quotes for until they look. A raised deck with standing room underneath makes frame repair straightforward. A deck 300 to 500 millimetres off the ground means every frame repair is done from above by lifting boards, which adds board handling, breakage and matching, and can double the cost of replacing a single joist. For projects that go beyond repair, patio and verandah installation and pergola builders cover the structures that often get added alongside, and doing them in one visit saves a second mobilisation.
| Job | Coastal Strip | Inner and Older Suburbs | Northern and Southern Corridors |
|---|---|---|---|
| Refix fixings, per square metre | $35-$60 | $30-$55 | $25-$50 |
| Sand and re-oil, per square metre | $32-$55 | $28-$50 | $25-$45 |
| Replace boards, per linear metre | $60-$110 | $55-$105 | $45-$90 |
| Replace a bearer or joist, per linear metre | $150-$280 | $130-$260 | $110-$230 |
| Replace a post and stirrup | $380-$650 | $340-$600 | $280-$520 |
| Balustrade repair, per metre | $240-$450 | $210-$420 | $180-$380 |
| Rebuild the frame and relay boards, per square metre | $280-$480 | $250-$450 | $220-$400 |
| Extra cost where the deck is under 500 mm off the ground | Add 40-80 per cent | Add 40-80 per cent | Add 40-80 per cent |
Regional Western Australia Pricing
Deck repairs travel better than most trades because the materials are available widely, so regional loadings are more modest here than on specialist work. Carpentry trades are strong through Mandurah and Peel and across the South West to Bunbury, Busselton and Margaret River, and the South West has proportionally more timber decks than Perth because the setting suits them. Loadings in those areas are small by comparison. Carpenters cover Albany, the Great Southern and Geraldton without difficulty, though matching an older hardwood may mean sourcing from a Perth timber yard.
Hardwood supply is the regional constraint worth planning around. Jarrah and merbau in a particular width, grade and colour are not stocked everywhere, and freighting long hardwood boards is awkward and they are easily damaged in transit. Where a repair needs matching timber, allow a lead time and order a generous margin rather than the exact linear metres. In the Goldfields, the Wheatbelt, the Pilbara and the Kimberley, rates run 30 to 70 per cent above metropolitan ones, so batch everything into one visit. Conditions change the approach in the north as well: coatings and oils have application temperature limits that a Pilbara summer day exceeds by the middle of the morning, so deck coating work up there belongs in the cooler months or at first light.
Bushfire prone areas are the regional factor that affects decks specifically. In the Perth hills, the South West, the Great Southern and much of the peri-urban fringe, a deck attached to a house in a designated bushfire prone area has construction requirements based on the assessed Bushfire Attack Level, and timber species, board gaps and the enclosure of the subfloor all come into it. Where the property is in the mapping, confirm the replacement detail before materials are ordered. Preparation and bushfire material for the state comes from the Department of Fire and Emergency Services.
| Region | Local Carpentry | Hardwood Matching | Loading on Metro Rates |
|---|---|---|---|
| Perth metro | Deep | Good, new and reclaimed | Base rate |
| Mandurah and Peel | Good | Good | 0-10 per cent |
| South West and Margaret River | Strong, many timber decks | Reasonable | 5-20 per cent |
| Albany and Great Southern | Good | Often from Perth | 15-30 per cent |
| Geraldton and Mid West | Adequate | Often from Perth | 20-40 per cent |
| Wheatbelt and Goldfields | Limited | Freighted, allow lead time | 30-55 per cent |
| Pilbara and Gascoyne | Limited | Freighted, coating season limited | 40-70 per cent |
| Kimberley | Thin | Freighted, wet season delays | 45-70 per cent |
What to Look Out For in a Deck Repair Quote
Deck quotes go wrong in one dominant way, and it comes down to whether anybody got underneath. The first question is what was probed and what was found. A contractor who has walked across the deck and quoted board replacement has priced what they could see. Ask whether bearers and joists were probed with a screwdriver at the post and wall connections, whether the stirrups were inspected at the concrete line, and ask to see photographs. Expect to pay a small inspection fee for that, and pay it willingly.
The second is where the quote draws the line between boards and frame. A quote for boards alone on a deck that springs underfoot is quoting the symptom, and the springing joist will still be there under new timber. Ask for a rate to apply if more rot or termite damage is found once boards come up, so that the variation is agreed in advance rather than negotiated once the deck is open. The third thing to settle is the balustrade. On any deck where a fall of a metre or more is possible, ask whether the existing barrier meets the one metre height, the 125 millimetre opening rule and the 40 millimetre floor gap, and whether the non-climbable band, meaning the zone between 150 and 760 millimetres above the floor, applies because the fall exceeds four metres. A repair that restores a non-compliant barrier to its original non-compliant state is a missed opportunity and a liability.
The fourth thing to settle is the specification itself. Which timber species and grade, what fixing specification given the distance to the coast, and will hardwood be pre-drilled. Then the matching question: who is sourcing boards, what happens if no match exists, and is a full sand and re-oil after the repair included so the new boards blend. That last item is what decides whether you are happy with the result.
Finally there is the paperwork and the cause. A written scope naming each member being replaced, a statement of what the contractor believes caused the failure, confirmation that spans and fixings follow the framing standard or an engineer, warranty terms including recurrence, and a deposit within the 6.5 per cent legal cap. For small ongoing maintenance between repairs, handyman services can usually cover it.
What to Settle Before the First Board Comes Up
What did you probe and what did you find, and may I see photographs. Were the stirrups inspected at the concrete line. Does the quote cover the frame or only the boards. What rate applies if more rot or termite damage appears once boards are lifted. Does the existing balustrade meet the current height, opening and floor gap requirements.
Then come the questions about material and finish. Which species and grade, and will hardwood be pre-drilled. What fixing specification, for a property this close to the coast or to a chlorinated pool. Who sources matching boards and what happens if no match exists. Is a full sand and re-oil after the repair included so new boards blend in. And name the deposit, which the law caps at 6.5 per cent of the contract price.
Probe results and photographs, frame included or excluded, a rate for hidden rot, barrier compliance, species and fixings, and the blending question settled.
Deck Repair Services Across Western Australia
We connect you with carpenters, decking specialists and builders throughout Western Australia for deck board replacement, frame and post repairs, balustrade work, sanding and oiling.
▶ Perth Inner City 17 areas
CBD & Surrounds
Inner North
Inner South
Western Suburbs
▶ Greater Perth 26 areas
Northern Suburbs
Southern Suburbs
Eastern Suburbs
Perth Hills
▶ South West 25 areas
Peel
Bunbury Region
Margaret River Region
Great Southern
▶ Regional Western Australia 30 areas
Pilbara
Kimberley
Goldfields
Mid West
Wheatbelt
Deck Repair FAQs
How much does a deck repair cost in Western Australia?
My deck feels springy underfoot. Is that serious?
Does my deck need a balustrade, and how high?
Do I need a building permit to repair my deck in WA?
Why do Perth decks get termites so often?
How often does a jarrah deck need oiling in Perth?
Can new boards be made to match my old deck?
Why have the nails in my coastal deck rusted but the timber is fine?
Is a composite deck maintenance free?
Should I pressure wash my deck before oiling it?
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