Subfloor Repair Services SA 2026 - Complete Cost Breakdown

Subfloor Repair Costs in South Australia for 2026

The subfloor is the part of a house nobody looks at until the floor starts telling them to.

Under any suspended timber floor there is a framework doing real structural work. Piers or stumps carry the load down to the ground, bearers span between them, joists span between the bearers, and the flooring sits on the joists. In South Australia that framework is usually supported on brick piers and honeycomb sleeper walls, not on the timber stumps that dominate Melbourne, which matters because brick and stone piers fail by a different mechanism and salt damp attacks them in a way it cannot attack timber. Pricing in 2026 runs from $350 for an inspection to $6,000 for substantial drainage works, with most single repairs falling between $900 and $3,500.

What separates a subfloor repair that holds from one that returns is whether anybody dealt with the water. Timber in a dry, ventilated subfloor lasts as long as the house. Timber in a damp, still subfloor rots, grows fungal decay, attracts borer and provides termites with exactly the conditions they need. Every one of those outcomes is a moisture outcome, so the sequence that works is finding the water, stopping it, improving the airflow, and only then replacing what the water ruined. Owners who reverse that order pay twice, and the second bill arrives seven to twelve years later.

There is one condition in this state that deserves naming at the top. South Australia has the highest incidence of salt damp in the country, driven by naturally saline groundwater across much of the settled area and a large stock of solid masonry built before damp courses were standard. Under a floor, salt damp attacks the piers and sleeper walls themselves, crumbling mortar and fretting brick and stone in the dark where nobody sees it. A subfloor inspection in South Australia that does not look specifically for it is incomplete, and our salt damp treatment guide covers the remediation side in detail.

Timber framing durability and subfloor ventilation requirements sit in the National Construction Code and the supporting Australian Standards published through Standards Australia, and termite management for new and remedial work has its own standard within that set. Structural repair work above the prescribed threshold is licensed building work in this state. Our building defect inspection guide explains what a thorough report should contain before you commission any of it.

What the Subfloor Is and What It Carries

A suspended floor is a structure in its own right, and knowing its parts makes every quote you read comprehensible.

Working from the ground up, the piers or stumps are vertical supports sitting on footings in the soil. On most South Australian houses these are brick, sometimes stone on older stock, and often arranged as honeycomb sleeper walls, which are low walls built with deliberate gaps so air can pass through. Timber stumps exist here but are much less common than in Victoria. On top of the piers sit the bearers, which are the heaviest timbers in the floor and run in one direction. Joists sit across the bearers at close centres, and the floorboards or sheet flooring sit on the joists.

Two more elements matter to the repair conversation. Ant capping is the metal flashing between the top of a pier and the timber above it, and it exists to make termite entry visible instead of blocking it. Subfloor vents are the openings through the external wall at or below floor level, and they are the entire ventilation strategy on most older houses.

A slab-on-ground house has none of these elements at all. Houses built in South Australia from roughly the 1970s onward are overwhelmingly slab, and if yours is one of them you do not have a subfloor at all. The problems that look similar on a slab, being floor movement and cracking, come from footing and soil behaviour instead, and our floor levelling guide covers that side.

The Signs That Something Is Wrong Below

Subfloor problems announce themselves upstairs long before anybody gets under the house, and the symptoms are specific enough to read.

A springy or bouncy patch in the floor is the most common and the most useful. It means the joist or bearer under that spot has lost stiffness, which comes either from decay or from a support that has dropped away underneath it. Walk the house slowly in socks and note where it gives. A floor that slopes, or a room where furniture rocks and a dropped marble rolls consistently in one direction, points at support that has moved, not timber that has softened.

Smell is the most underrated signal of the lot. A persistent musty or earthy odour in a room with no obvious damp, strongest near skirtings or a floor vent, is subfloor air entering the house, and subfloor air only smells like that when the space below is wet. Mould appearing low on internal walls or behind furniture on an external wall follows the same mechanism.

Several other indicators are worth having in mind. Floorboards that have cupped, meaning the edges have lifted higher than the centre, indicate moisture coming up through them from below. Gaps opening between boards that were tight, or closing up in boards that had gaps, indicate seasonal moisture swings in the subfloor. Skirtings pulling away from the wall or a door that has started to bind at the bottom suggests the floor has moved. And an unexplained rise in a termite inspection finding year to year tends to be the subfloor becoming more hospitable.

None of these tells you which repair you need. That is what the inspection is there to establish. They do tell you whether to arrange one, and in almost every case the answer is yes. Our structural inspection guide and mould inspection guide cover the two reports that most often apply here.

Moisture, the Cause Behind Almost Everything

Find the water and you have found the job. Everything else under a floor is a consequence.

Subfloor moisture arrives by a short list of routes, and an inspector worth paying works through all of them. Surface water running under the house during rain, usually because the ground outside slopes toward the building or because paving and garden beds have been built up over the years until the external ground sits above the internal floor level. Stormwater discharging too close to the footings, a downpipe problem and one of the cheapest to correct. Leaking plumbing, most often a slowly weeping supply joint or a failed shower waste, which produces wet soil in one identifiable area. Groundwater rising through the soil in low-lying ground. And humid air entering a poorly ventilated space and condensing on cool timber and masonry.

The distribution of the damp tells you which route it took. Wet soil in a single patch under a wet area points at plumbing. Damp across the whole subfloor that worsens after rain points at surface water or drainage. Damp that is worst along one external wall points at ground levels or a downpipe on that side. Consistent dampness with no rain correlation and no plumbing in the vicinity points at groundwater or ventilation.

One measurement settles most arguments about this. A moisture meter reading taken in the bearers and joists, compared between an affected area and an unaffected one, converts an opinion into a number, and a competent inspection report will contain those readings with their locations. Ask for those readings and the locations they were taken at. A report that describes the subfloor as damp without a single reading in it is a description, not a diagnosis.

The repairs that address cause are cheaper than the repairs that address damage. That is the fact most worth carrying into your first quote. Redirecting a downpipe and cutting back a garden bed might cost a few hundred dollars. Replacing the bearers that the downpipe rotted over fifteen years costs thousands. Our leak detection guide covers finding a plumbing source, and stormwater drainage covers getting roof water away from the building.

Ventilation Requirements and Upgrades

Air movement is the cheapest structural protection a suspended floor has, and most older South Australian houses do not have enough of it.

The principle at work here is cross flow. Air needs to enter on one side of the house and leave on the other, which means vents on opposite walls and an unobstructed path between them. A subfloor with vents only on the front and back, or with internal sleeper walls that have had their honeycomb gaps filled in during a past renovation, has dead zones where air does not move and moisture sits. Those dead zones are where the rot always is, and an inspector who maps airflow instead of counting vents is worth the fee.

Passive upgrades come first because they are cheap and they often suffice. Clearing vents that have blocked up costs almost nothing at all. Cutting additional vents into masonry walls runs $600 to $1,800 for a reasonable number, and replacing small terracotta grilles with larger modern ones much increases the open area for a modest sum. Removing debris and builders rubble from inside the subfloor, which obstructs airflow in a great many houses, is labour, not materials.

Mechanical ventilation is the next step where passive measures cannot deliver. A fan system running on a timer or a humidity sensor, extracting damp air from the dead zones and drawing fresh air through the vents, costs $1,800 to $4,500 installed with the electrical work. Envirofan is one of the established Australian systems in this category and is commonly installed by pest and building firms rather than by electricians alone. It is the right answer for a tight subfloor with limited wall area for vents, for a house hemmed in by neighbouring buildings, and for the persistent condensation pattern. It is the wrong answer where the real problem is water entering the subfloor, because a fan cannot dry out soil that is being refilled every time it rains.

Sequencing saves real money here, and it goes in one direction. Have the drainage and ground levels sorted before you size a ventilation system, because the system you need for a dry subfloor is smaller and cheaper than the one you need for a wet one. Our subfloor ventilation guide covers the installation side and underfloor insulation explains how insulation interacts with airflow, since insulating a damp subfloor without fixing the damp makes things worse. Bradford and Earthwool are the two underfloor batt ranges most widely stocked in Australia, and either is fine in a dry subfloor and a mistake in a wet one.

Salt Damp Under a South Australian Floor

Salt damp is the condition that makes subfloor work in this state different from subfloor work anywhere else in the country.

The mechanism is capillary action carrying groundwater up through porous masonry, and because much South Australian groundwater is naturally saline, that water carries dissolved salt with it. Water evaporates at the surface of the brick or stone and the salt stays behind. Salt crystals occupy more space than the solution they came from, so they exert pressure inside the pores of the masonry and progressively break it apart. The visible result is fretting brick, crumbling mortar, a powdery white bloom, and eventually a course of masonry that has lost its face.

What owners as a rule miss is that this happens to the piers and sleeper walls under the floor as well as to the walls they can see, and in the subfloor it progresses faster. The space is darker, damper and less ventilated, there is no sun to dry the surfaces, and nobody inspects it. A pier that has lost its mortar joints and fretted back is carrying load on a reduced section, and eventually the bearer above it drops.

Older solid masonry stock built before damp courses became standard is the affected category, which in practice means much of the pre-1920s and a good deal of the interwar housing across the inner metropolitan suburbs, the Mid North, the Clare and Barossa valleys and the country towns. Suburbs on naturally saline ground are worst affected, and in those areas it is close to universal in the older stock.

Remediation is its own trade and its own quote. The work typically involves installing a damp course by chemical injection or physical insertion, rebuilding the fretted masonry, removing salt-contaminated render and sometimes lowering ground levels, and it runs from $2,500 for a limited area to well over $12,000 for a whole house. Doing timber repairs under a floor without addressing active salt damp in the piers that carry it is building on a failing base. Our salt damp treatment guide prices that work properly and rising damp treatment covers the related non-saline condition.

Rot, Fungal Decay and Borer

Three different things eat subfloor timber and they are commonly confused with each other, which matters because the response differs for each.

Wet rot is by far the most common of the three. A fungus active in timber above roughly twenty percent moisture content, it softens and darkens the wood, which eventually crumbles under a screwdriver pushed into it. Wet rot stops when the timber dries, so the repair is remove the water, replace the destroyed timber, and the problem is over. It concentrates at bearing points, meaning where a joist sits on a bearer or a bearer sits on a pier, because that is where moisture is trapped against end grain.

Dry rot, which is a misleading name for a fungus that still needs moisture to establish, is the serious one. It can transport water through its own structure and spread into timber that would otherwise be dry, crossing masonry to do it, and it leaves a distinctive pattern of cracking that breaks the timber into small cubes, with white or grey fungal strands across it. It is much less common in Australia than in Britain but it does occur. Where an inspector identifies it the scope expands, because the extent of removal has to go beyond the visibly affected timber.

Borer is an insect problem, not a fungal one. The common species here attack softwoods, which in South Australia usually means the Baltic pine flooring and softwood joists found in older houses, and the sign is small round exit holes with fine powdery frass below them. The important question with borer is whether the infestation is active, which a borer specialist determines from fresh frass and the condition of the holes. Historic borer damage in otherwise sound timber frequently needs no treatment at all.

A screwdriver and a torch will give you a useful first read. Press the tip firmly into bearers and joists at their ends and bearing points. Sound timber resists the point and decayed timber gives way under it. That test will not grade the extent and it will not tell you the species of anything, but it will tell you whether to be worried, and it is worth doing before you pay for a report. Our carpentry services guide covers the replacement work and mould and damp treatment covers the associated indoor air problem.

Termites in South Australia

South Australia carries real termite risk, and the common assumption that it is a problem for the eastern states only has cost people money here.

Risk is uneven across the state instead of uniform. Pressure is highest in the Adelaide Hills and the foothills suburbs, along the River Murray corridor and through the Riverland, and in areas with established eucalypts and old stumps in the ground. It is lower on the open plains and lower again in the dry pastoral country, though lower is not the same as absent. The species of economic concern builds nests away from the building and sends workers to it through the soil, and that is precisely why the subfloor is the battleground.

A damp, poorly ventilated subfloor is an invitation. Termites need moisture, and the conditions that cause rot cause termite attraction at once, which is one of the strongest practical arguments for spending on ventilation and drainage. Timber in contact with soil under a house, which includes offcuts and form work left behind by builders, stored timber, and old stumps, is both a food source and a bridge.

Inspection frequency is the single most useful thing an owner can control. Annual timber pest inspection is the general recommendation, more often in the higher risk districts, and it costs $280 to $550 in South Australia. Against that, a termite repair bill in a subfloor runs into five figures without difficulty. The inspection is also the mechanism by which ant capping does its job, since capping does not stop termites but forces them into the open where an inspector sees them.

Treatment and timber repair are separate exercises with separate quotes, and the order matters. Treat the colony first, then repair the timber, because replacing timber while an active colony is present provides fresh food. Proprietary systems are what installers work with, and Termidor and Kordon are two of the names most often specified in Australia, the first a chemical soil treatment and the second a physical barrier laid during construction. Which is appropriate depends on whether the work is remedial or preventive, and a licensed inspector will tell you. Termite management in buildings is governed by its own Australian Standard, and biosecurity and land management information for the state is published through Primary Industries and Regions South Australia. Our termite inspection guide and termite treatment guide price both sides.

Piers, Stumps and Sleeper Walls

The supports under a floor are where South Australian practice diverges most sharply from the restumping industry people read about online.

In Victoria the standard conversation is timber stumps and replacing them with concrete, and the cost language of the whole trade comes from there. Here the supports under a solid masonry house are usually brick piers and honeycomb sleeper walls, which fail by mortar decay, salt damp fretting and footing settlement, not by rotting off at ground level. Timber stumps do appear, more often in post-war timber-framed and transportable housing and in some Hills construction, and those behave as the Victorian literature describes.

Replacing a pier runs $450 to $1,200 each, and the spread inside that range is almost entirely access and what the pier is made of. A brick pier in a 600 millimetre subfloor near an access hatch is at the bottom end. A stone pier in the middle of a 200 millimetre subfloor, reached by crawling fifteen metres, is at the top. Rebuilding a section of honeycomb sleeper wall is priced by the metre at $400 to $900.

There is a question worth asking of any quote that proposes replacing supports. Any quote proposing to replace supports should be able to say why this one failed and whether the replacement will face the same conditions. A brick pier that fretted because salt damp is active in the soil beneath it will do it again, so the specification matters, and so does whether anybody is addressing the damp. A pier that settled because the clay under it shrinks and swells needs a footing answer and not a pier answer, which pushes the job toward underpinning territory.

Jacking is the part owners should ask about explicitly. Lifting a floor back to level puts stress through everything above it, and done quickly it cracks plaster, jams doors and in bad cases damages masonry. Done properly it is slow and staged over weeks. Our restumping guide and stump replacement guide cover the methods in detail.

Where the movement runs across the whole building rather than one corner, the exercise changes name and scale. Lifting an entire house back to level is a staged operation measured in weeks, and our house levelling guide prices that version of the work separately.

Bearers, Joists and Floor Framing

Bearers and joists are the timbers that actually fail, and replacing them is the work most subfloor quotes are mostly made of.

A bearer replacement runs $900 to $2,400 for a single span. The work involves propping the floor above, removing the old timber, installing new material of the correct size and grade on proper bearings, and reinstating any joist connections. Joists are cheaper at $350 to $900 each because they are smaller and lighter, though a joist in the middle of a room with a kitchen above it costs more than one near a hatch. Replacing a whole floor frame across a room is priced per square metre at $180 to $420.

Partial replacement is often the right answer and it is worth asking about. Where decay is confined to the last few hundred millimetres of a joist at its bearing point, the commonest pattern, a competent carpenter can cut back to sound timber and splice or sister a new length alongside instead of replacing the full member. That is materially cheaper and structurally sound when it is done properly, and a quote that proposes full replacement of every affected joist without discussing it is worth questioning.

Two specification points separate a good job from a cheap one. The new timber should be a durability class and treatment level appropriate to a subfloor, not whatever was on the truck, because untreated softwood in a damp subfloor is a repeat job waiting to happen. And the new bearing points should have something between timber and masonry, whether a damp proof course material or a metal plate, so moisture in the brickwork does not wick straight into the end grain of the new bearer the way it did into the old one.

Insist that the quote states the sizes and grades it is pricing. Timber framing sizes and spans for residential construction come from the relevant Australian Standard, available through Standards Australia, and a builder working to it will have no difficulty writing the specification down. Our timber flooring guide covers the surface above and structural engineer guide covers when engineering input is required.

Floor Levelling and Movement

A sloping floor and a bouncy floor are different problems with different causes, and the distinction decides the quote.

Bounce means loss of stiffness in the framing. A joist has decayed, a bearer has softened, a span is too long for the timber in it, or a support has dropped away from under the timber it was carrying. The repair is in the framing or the support, and it is usually localised to where you can feel it.

Slope means the supports underneath have moved out of position. Either a footing has settled, or a pier has reduced in height through fretting or crushing, or the whole corner of the house has gone down. The repair is in the supports and the ground under them, and it routinely covers a larger area than the slope you noticed.

Levelling work is priced according to how much of it there is. Packing and shimming individual support points to take out a modest variation runs $120 to $300 per point. Re-levelling a room properly, with jacking staged over time, runs $1,200 to $3,500. A whole house is a different exercise again and belongs in house levelling territory. One question to settle before committing is how level is level, because chasing a perfectly flat floor in a century-old house can cost a great deal and crack a great deal of plaster for a result nobody notices.

There is a staging decision here worth understanding in advance. Jacking a floor transfers stress into walls, ceilings and door frames, and the slower it is done the less damage results. A contractor who proposes to take out a fifty millimetre slope in one afternoon is proposing to crack your cornices. Ask for the lift to be staged and for the expected cosmetic consequences to be named in writing. Our floor levelling guide covers the methods and building defect inspection covers establishing the cause first.

Subfloor Drainage and Site Water

Where water is entering the subfloor from the site, drainage is the repair and everything else is tidying up afterwards.

The cheapest interventions come first and they are often enough. Extending or redirecting downpipe discharge so roof water leaves the building rather than soaking in beside the footings costs $250 to $900 and fixes a surprising proportion of localised subfloor damp. Regrading the ground so it falls away from the walls, and removing paving or garden beds that have trapped water against the masonry, is labour at a few hundred dollars per elevation.

Where surface measures cannot do it, subsurface drainage is next. An agricultural drain, meaning a perforated pipe in a gravel-filled trench wrapped in filter fabric, laid along the affected elevations and taken to a legal discharge point, runs $1,500 to $6,000 depending on length, depth and what the ground is made of. Digging an ag line through Adelaide clay is slower than digging one through sand, and that shows in the price.

The discharge point is the part that catches people out. Water collected by a drain has to go somewhere lawful, and where the site falls away to the street that is straightforward, but on a flat block or one that falls toward a neighbour it becomes a design problem. A sump with a pump is the usual answer at $1,200 to $3,500 including the electrical work, and it introduces a maintenance obligation and a failure mode that did not exist before, which is worth knowing before you choose it over other options.

One caution is worth stating about sealing. Applying a waterproof coating to the inside of subfloor masonry to keep damp out sounds appealing and frequently makes things worse, because it traps moisture inside the wall and drives evaporation and salt crystallisation further up. Masonry in a damp subfloor generally needs to be able to breathe while the water is removed from the outside. Our stormwater drainage guide and waterproofing services guide cover the two approaches and when each applies.

Access and Clearance, the Real Cost Driver

Two identical repairs in two different subfloors can differ in price by a factor of two, and clearance is usually the reason.

A subfloor with 600 millimetres or more of headroom lets a tradesperson crawl, carry material, use tools normally and work at a reasonable rate. One with 300 millimetres means working on the stomach, dragging timber in by hand, cutting outside and passing pieces through, and taking rest breaks. Below about 200 millimetres a great deal of work becomes impractical from below altogether, and the alternative is lifting floorboards and working from above.

That alternative costs money in a different place. Lifting and reinstating tongue and groove flooring, particularly old Baltic pine that splits and cannot be bought new in matching widths, adds much to a job and carries a risk of visible repair lines in the finished floor. On a carpeted floor it is far less consequential. On a polished heritage floor it is a real consideration and worth discussing before the method is chosen for you.

Access hatches are worth attention in their own right. A great many South Australian houses have a single small hatch in a cupboard or an external wall, which means every piece of material and every tool goes through that opening and every trip starts there. Where repeated subfloor work is likely, and in a house with persistent damp it is likely, cutting a second and larger access point is a modest cost that pays for itself on the next job.

Two other access factors show up in quotes. Services running through the subfloor, meaning pipes, ducts, wiring and sometimes old asbestos-containing material, obstruct movement and occasionally require another trade before work proceeds. And a subfloor that is wet at the time of the work is slower and less safe than a dry one, which is a practical argument for doing drainage first and timber second. Our asbestos removal guide covers what to do if suspect material is found and handyman services covers minor access improvements.

Inspection and Who to Call First

The first phone call on a subfloor problem decides how much of the next one you waste.

A building inspector or building consultant with subfloor experience is the right starting point for most situations. The report costs $350 to $800, covers moisture readings, timber condition, ventilation adequacy, support condition and the likely sources of water, and gives you a document three builders can quote against the same way. Comparability is where the saving sits, because without it every builder quotes a different scope and none of the numbers are comparable.

A licensed timber pest inspector is the right first call where there is any suggestion of termite activity, and the two inspections tend to be done together or by the same practitioner. Where the floor has moved rather than softened, meaning slope and cracking rather than bounce and decay, a structural engineer is the correct first opinion and will cost $600 to $1,800 for an assessment with a report.

A specific builder is the wrong first call, and the reason is not that builders are untrustworthy. It is that a builder is quoting the work they do, so the diagnosis and the quote come from the same party, and on a problem with several possible causes that is a structural weakness in the process, not a comment on anybody. Get the diagnosis independently and the quotes separately.

Ask what the inspection will include before you book it. A thorough subfloor inspection means physical entry to the subfloor and movement through it, not a look through the hatch with a torch, and the report should name the areas entered and any areas that could not be reached. Moisture readings with locations, photographs, an assessment of ventilation adequacy and a clear statement of probable cause are the four things that make a report useful. Health guidance on mould and indoor damp for South Australia is published through SA Health. Our pre-purchase pest inspection guide and mould removal guide cover the adjacent reports.

Adelaide Metropolitan Pricing Variations

Pricing across metropolitan Adelaide follows the age of the housing stock closely, because age determines whether there is a subfloor at all and what it is made of.

The pre-1920s inner suburbs are the most expensive and the most likely to need work. Solid stone and brick construction, brick or stone piers on honeycomb sleeper walls, low clearances, salt damp prevalence and original Baltic pine flooring that is awkward to lift all push the numbers up. Inner northern, eastern and western suburbs through this era commonly combine three separate items in one job, which is the moisture work, the masonry support work and the timber work.

The interwar and post-war suburbs sit in the middle and hold the largest number of houses with suspended floors in the state. Construction is more consistent, clearances are often better, and the common findings are decayed bearer ends, blocked or insufficient ventilation and localised damp from drainage. This is the mainstream subfloor job and the range most quotes land in.

The foothills and Hills face suburbs are a separate case on both risk and access. Sloping blocks produce deep subfloors at one end and almost none at the other, so access varies within a single house. Higher rainfall, more established eucalypts and greater termite pressure make inspection frequency more important here than anywhere else in the metropolitan area.

From the 1970s onward the northern and outer southern growth corridors are overwhelmingly slab on ground, which means no subfloor and a different set of problems. Owners in those areas who have been told they need subfloor work should establish first that they have a subfloor, because floor movement on a slab is a footing and soil question. Out along the beachside suburbs the difference is one of specification instead of construction, since sandy soil drains freely but salt-laden air and a high water table in some pockets affect material choices.

Regional South Australian Pricing Patterns

Regional subfloor work prices differently from metropolitan work, and the reasons have more to do with the buildings than with distance.

Country town housing across the Mid North, the Clare and Barossa valleys, the Flinders fringe and the Limestone Coast is heavily weighted toward older solid masonry with suspended timber floors, the stock that needs this work. A far higher proportion of houses in Burra, Kapunda, Peterborough, Gladstone or Penola have subfloors than in a northern Adelaide suburb, and a far higher proportion of those subfloors sit on stone piers in saline ground.

Salt damp is the single largest regional differentiator. Groundwater salinity across the agricultural districts and the Murray corridor is high, the housing predates damp courses, and the result is that subfloor masonry deterioration is the normal condition rather than the exception in some towns. An inspection in that stock should expect to find it, and an owner budgeting for a subfloor repair in those districts should budget for remediation alongside the timber work rather than hoping to avoid it.

Trade availability shapes most of what is left. Carpenters and builders work in every regional centre, so the timber side of the work prices close to Adelaide rates once a travel charge of $150 to $450 is added. The specialist trades are where the constraint sits. Restumping contractors, salt damp remediation operators and licensed timber pest inspectors are concentrated in the larger centres, meaning Mount Gambier, Whyalla, Port Lincoln, Port Augusta, Murray Bridge and the Riverland towns, and properties away from those centres wait longer and pay more for the specialist components.

Two environmental factors split the state fairly cleanly. Down in the far south east, around Mount Gambier and Penola, wet winters and a damp climate shorten the timeline to decay more than anywhere else in South Australia, so ventilation and drainage carry the most weight there and inspections should come round more often. The dry inland country, which takes in the Murray and Mallee districts, the agricultural north and the pastoral zone beyond it, slows decay a good deal, and damp discovered in those parts almost always traces to one identifiable source such as irrigation, a weeping service or a drainage fault.

The unoccupied property problem deserves its own mention. Holiday houses on the Yorke Peninsula, the Fleurieu and the Limestone Coast sit unvisited for months, and a subfloor that becomes wet in May is discovered in December with the decay well advanced and sometimes with termites established. A twenty minute look under the house on each visit, and a request to a neighbour to check after heavy rain, costs nothing and catches these early. Our damp proofing guide and pest control guide cover the preventive side.

How to Get and Compare Subfloor Repair Quotes

Subfloor quotes are among the hardest in domestic building to compare, and the reason is that nobody can see the whole problem.

Parts of every subfloor are unreachable, so every quote contains assumptions about what is happening in the areas nobody inspected. The honest ones say so and price a rate for additional work found during the job. The ones that do not say so are not more confident, they are simply quieter about the same uncertainty, and the variation arrives later. Ask every builder directly what they are assuming about the areas that were not accessible.

Start with the independent inspection and give every quoting builder the same report. This is the single highest-value thing an owner can do in this category. Three builders quoting from one report produce three numbers for one scope, which you can actually compare. Three builders each forming their own view produce three different jobs at three different prices, and choosing between them is guesswork.

Check that the quote separates cause from damage. There should be line items for the moisture work, meaning drainage, ground levels and ventilation, and separate line items for the timber and support work. A quote that prices only the timber is quoting half the job, and the half it has left out is the half that determines whether the repair lasts. If a builder tells you the moisture work is unnecessary, ask them to put that in writing with their reasoning.

Two separate licences can be in play here and both are easy to verify. Building work of any structural significance has to be carried out under a building work contractor licence, while timber pest treatment sits under its own licensing regime, and a single job can require both. Search each one through Consumer and Business Services and check that the trading name, the licence holder and the bank account on the invoice all belong together. A written building contract becomes mandatory once the value passes the statutory figure.

Work health and safety obligations apply to confined and restricted spaces, and a subfloor with limited clearance is exactly that. Requirements for South Australian workplaces are administered through SafeWork SA. Anybody treating a 250 millimetre subfloor as an ordinary work area without comment is worth a second thought, both for their sake and for the standard of work you will get out of an uncomfortable space.

Keep every piece of the paperwork. The inspection report, the quotes, the contract, photographs of the subfloor before and after, and the specification of what timber was installed all matter if something goes wrong later, and the path for a building dispute here runs through a conciliation conference convened by Consumer and Business Services and then a claim in the Magistrates Court of South Australia. SACAT handles something different, being disciplinary action against licensed contractors rather than your claim. Our structural inspection guide and black mould removal guide cover the related reports and remediation.