What rising damp treatment actually costs in Australia

The per-linear-metre rate, and what it does and does not buy

A chemical damp-proof course is priced by the linear metre of wall treated. The published Australian band is $120 to $400 per linear metre, commonly $180 to $300. That band is wide because the work behind it genuinely varies, not because the trade is being coy.

What the rate covers is the injection itself: the installer drills holes of 10 to 15 mm diameter at roughly 120 mm centres — about eight holes per linear metre — to within about 30 mm of the far face of the wall, and introduces a silane or siloxane cream or fluid so that a continuous water-repellent zone forms through the full thickness of the masonry. On a 230 mm one-brick wall the header course is drilled by preference; where a stretcher course is drilled instead, the stretchers on the other side of the wall have to be treated too, either from the far face or by re-drilling through the same holes in a second phase. That single detail can double the hole count and the product volume on the same run of wall.

What the rate does not cover, unless a quote says in writing that it does: excavation or paving removal to reach the correct set-out height, render cut back where it is bridging the course, grouting of voids in thick or rubble walls before injection, desalination, removal of salt-contaminated render or plaster, replastering, redecoration, skirting replacement, and any internal work, which requires plaster to come off and go back.

A whole-house injection component commonly lands between $3,500 and $15,000 before any replastering. An 18 metre terrace perimeter commonly runs $4,000 to $8,000 for the injection alone. On most properly sequenced jobs the injection is not the largest number on the page.

Published rates, item by item

The table below is the whole job, not just the part a licensed waterproofer does. The items marked as a licensed waterproofer's are the two things they perform: a chemical damp-proof course injected into the mortar bed of external brickwork, and a Hydropoxy epoxy moisture barrier applied to the top of an internal concrete slab before new flooring. They also attend and diagnose, and that part normally carries no charge. A licensed waterproofer holds, and where the sums on this page end up pointing at masonry work rather than housekeeping, that is the trade to engage. Everything else belongs to another trade, and the figure is here so you know roughly what you are looking at before you ring them.

What moves a job inside those ranges

Nine variables account for most of the spread. If a quote sits at an unexpected point in the band, one of these usually explains it, and a contractor should be able to say which.

• Wall thickness, and whether one face or both need treating. A 230 mm one-brick wall drilled on the stretcher course needs the far-side stretchers treated as well, which changes hole count, product volume and labour on the same run of wall.
• Hole count at correct spacing. Roughly 120 mm centres means about eight holes per linear metre. Wider spacing is cheaper to deliver and produces incomplete coverage.
• Material. Regular brickwork with continuous mortar joints is the straightforward case. Rubble stone can need enveloping patterns of holes above, below and beside each unit, and voids in thick or rubble walls swallow product and must be grouted before injection.
• Product. Active silane or siloxane content varies from roughly 15 per cent to roughly 80 per cent between certified products. The certificate for the specific product matters more than the word on the tin.
• Access. Internal work means plaster removal and reinstatement. Two-storey work means scaffold. Both are cost step-changes rather than increments.
• Wall condition. Very wet masonry limits diffusion, and crumbling mortar will not hold the treatment and needs repointing first — which then has to be allowed to cure, because extensive repointing can bridge the treated course and force re-treatment.
• Set-out height. The course must sit 150 to 250 mm above finished ground, with 200 mm the recommended target, and below all floor timbers. Where the ground or paving sits above that, the level work comes first and concrete cutting and disposal is the main cost step-change in it.
• Salt loading. Heavy salt banding brings desalination into the scope, and on a badly loaded wall it can exceed the cost of the damp course. Coastal and canal-front walls here carry chloride from saline groundwater and from sea air on top of whatever the wall started with, so this line comes up locally more often than the national guides imply.
• Location and occupancy. Regional and remote work carries a substantial premium, and an occupied house costs more to work in than an empty one.

Four things that turn a cheap quote into an expensive job

These are the four items most often absent from a low quote and most often present on the final invoice. None of them is a surprise to the trade. All of them are visible to anyone who walks the outside of the building properly, which is exactly why the diagnosis should come before the price — and why an inspection that costs nothing removes the last excuse for doing it the other way round.

1. The wall needs both faces treated, not oneOn a 230 mm one-brick wall, the header course is drilled by preference. Where a stretcher course is drilled instead, the stretchers on the other side must also be treated — from the far face, or by re-drilling through the same holes in a second phase. A quote priced for one face on a wall that needs two is not cheaper; it is a different, smaller job that will not form a continuous barrier. If the second face is internal, plaster removal and reinstatement comes with it at $40 to $120 per m² to remove and $80 to $180 per m² to replaster.
2. The course has to be set out at the correct height, and getting there is excavationA remedial damp course belongs 150 to 250 mm above finished ground, 200 mm being the recommended target, and the NCC requires a damp course not less than 150 mm above adjacent ground level. Where soil, mulch, paving or a path sits above that line, the levels are corrected first: $500 to $6,000, with concrete cutting and disposal the main step-change inside that range. Render that is bridging the course has to be cut back and a clean drip formed. Neither of those is included in a per-linear-metre injection rate. In this part of the world it is the single most common finding, because gardens and paving have had thirty years to climb.
3. Heavy salt loading means desalinationA chemical damp course stops water rising past it and does nothing whatever about salt already in the wall above it. Those salts keep dissolving in humid weather and re-crystallising in dry weather, and each cycle breaks the masonry down further. The conventional threshold at which desalination enters the scope is about 0.5 per cent salt by weight, which is a laboratory figure; on site it announces itself as a white bloom, crumbling mortar and render that has let go in a band. Desalination runs $80 to $250 per m², often $2,000 to $10,000 per job, it is iterative, and it should begin before or alongside injection, because injecting a wall can displace saline moisture upward into masonry that was previously undamaged. It is the single line item most often missing from a cheap quote.
4. Making good usually costs more than the injection didRender removal at $40 to $120 per m², replastering at $80 to $180 per m² in a standard system or $200 to $400 per m² in heritage lime, redecoration at $40 to $90 per m², and skirting replacement at $40 to $90 per linear metre. On a wall stripped to 1.25 metres over a long perimeter, those four lines together routinely exceed the injection. And if the render or paint is pre-1990, asbestos and lead obligations apply before anything is disturbed, which changes the cost category rather than the cost.

Why a rate below the band is a warning, not a bargain

This is the part of the page that costs a licensed waterproofer work, so it is worth being precise about the mechanism rather than gesturing at it.

Damp-coursing fluid and cream are expensive materials. That creates direct cost pressure on a contractor bidding low, and the Australian heritage guide names the two responses in print: diluting the fluid with extra solvent, or spacing the drill holes wider than recommended. Both produce incomplete coverage. A third mechanism is treating a wall from one side when it needs both. Good operators do the opposite — they deliberately over-apply to be certain of penetration, and that costs more per metre, not less.

What makes this different from ordinary corner-cutting is that the failure is invisible and delayed. The evidence is sealed inside a wall. Change in masonry is slow in both directions: in the standard worked example it takes about 31 days to reach 95 per cent of the steady height of rise, and that figure runs inversely with evaporation rate, so behind a coating or in a poorly ventilated space it can be years. A wall rendered to 1.25 metres takes roughly 425 days for the damp front to re-emerge above the render. A treatment that still looks fine at three months has proved nothing at all, and by the time an under-dosed course announces itself, two or three years of trading has happened.

So the useful response to a low number is not relief and it is not suspicion. It is six written questions, and any competent contractor can answer all of them in a paragraph.

The published Australian figures disagree by a factor of seven

Ranges published in Australia for the same chemical damp-proof course include $55 to $160, $70 to $350, $150 to $350 and $200 to $400 per linear metre. Two operators publish no rate at all and instead undertake to beat any written quote, which is price competition without price disclosure — and downward price pressure on this particular trade is the exact condition the heritage guide identifies as producing dilution and widened drill spacing.

A five-fold or seven-fold internal spread is not pricing transparency either. A range that wide, published without the scope beside it, tells a homeowner nothing they can act on.

The band a licensed waterproofer quotes against is $120 to $400 per linear metre, commonly $180 to $300, and every figure on this page is scoped so it can be checked.

The cost of the things that are not a damp course

Plenty of what gets called rising damp on the Gold Coast genuinely is rising damp — shallow saline water tables, subtropical rain and thirty years of accumulated garden beds see to that. Plenty of it is not. The two look similar from the kitchen and cost wildly different amounts to fix, which is the entire reason the visit happens before the quote.

The list below is the part of the market nobody advertises, because there is no product attached to it. Sometimes it is the whole answer and the masonry line stays at zero. Sometimes it is a prerequisite that has to be corrected before a damp course is worth installing at all. Either way it gets done first.

The comparison worth making is not between two damp course quotes. It is between the cheapest correct answer and the most expensive incorrect one.

Drying time is a cost, and it appears on nobody's quote

Cutting the source does not dry the wall. It stops the wall being resupplied. Everything already in the masonry then leaves by evaporation on the wall's schedule.

The working rule of thumb, from BRE Digest 163, is roughly one month of drying per 25 mm of wall thickness, which puts a 230 mm solid or double-brick wall at around nine months. The Australian heritage guide arrives at the same broad answer from a different direction: 3 to 6 months after replastering, or up to 12 months for wet thick walls. Treat the 25 mm rule as an order-of-magnitude expectation rather than a specification — it was framed around drying construction moisture, not a salt-loaded wall recovering from decades of rising damp. In a humid coastal summer, assume the slower end of every one of those figures.

The financial consequence is that making good is deferred, not cancelled. Replastering, repainting and skirting replacement — the $40 to $120, $80 to $180, $40 to $90 per square metre and $40 to $90 per linear metre lines — get spent months after the injection, sometimes in a different financial year, and they get spent twice if they are spent early. Repainting a wall that has not dried produces blistering that is close to guaranteed. Wallpaper should not go on for at least 12 months, longer on thick walls.

There is one further cost that never appears on a quotation: a room may be out of use, or half-finished, for the better part of a year. And there is a trap in how you judge the end of it. A salt-contaminated wall may never read dry on a meter, because hygroscopic salts hold moisture out of the air indefinitely — the meter is reading conductivity, and salt conducts. So the honest test of a treated wall is behavioural: no fresh salting through the render, no dark band creeping back up through a full wet season, plaster staying put. Where that is genuinely contested — an insurer, a dispute, a buyer who needs a number — laboratory sampling is what settles it, and the next-but-one section explains what that involves.

A worked sum at the cheap end

The two sums that follow are arithmetic, not case studies. They are not jobs a licensed waterproofer has done and no property, owner or outcome is being described. Every unit rate is taken from the published bands in the table above, so the sums can be checked line by line.

The first is the common case: a 1970s brick veneer house, damp along one external wall to about 400 mm, a garden bed built up against that wall over the years, and a downpipe discharging beside it. Eleven metres of affected wall.

A worked sum at the expensive end

The second is the case the whole industry advertises and rarely sequences properly: a pre-1900 solid brick house with no damp course, 34 linear metres of affected external wall, salt loading heavy enough to be past the conventional 0.5 per cent by weight threshold, and render drummy to about 1.25 metres internally — roughly 42 square metres of wall face to strip and reinstate.

Note the proportion. The chemical damp course, which is the only line on this list that is the waterproofer's work, is $8,160 of $38,340. That is just over a fifth of the job. A quote that consists only of that line, at a rate below the band, is not a cheaper version of this sum. It is a fifth of it.

What the diagnosis costs, and when it is worth commissioning a laboratory one

The diagnosis costs nothing. A licensed waterproofer attends, and what they do on site is a deep visual inspection of the wall inside and out, an analysis of the drainage and the ground conditions around it, and identification of the factors actually causing the damp, with a moisture meter used where it helps. There is no fee and no report to buy.

That is a real diagnosis, and on most walls it is a sufficient one, because rising damp leaves an unusually legible set of tracks. Where do the finished ground levels sit relative to the damp course, and has a garden bed or a path buried it. Which way does the ground fall in the first metre. Where does every downpipe actually discharge. Is there a subfloor, and does air move through it. How high does the damp go, and is the top edge the flat, ragged band that capillary rise produces or the localised plume of a leak. Is there salt banding, and where. Does the wall change with the season or with the last storm. Read together, those answers separate a buried damp course from a downpipe from a shower membrane from condensation, and they do it before anybody has spent money.

The meter is one input among those, not the finding. A moisture meter on masonry measures electrical conductivity, and salt conducts beautifully, so a salted wall reads high whether or not there is free water in it — which is also why a treated wall may never read dry. Used as a comparison across a wall and a pointer to where to look harder, a meter is genuinely useful. Used as the sole basis for a five-figure quote, it is not, and any contractor whose entire case is a number on a screen should be asked what the ground levels and the drainage told them.

Then there is the other kind of investigation, the forensic one, and it is worth knowing what it involves so you can tell when you actually need it. Drilled samples are taken from measured depths and heights, oven-dried to give total moisture content by dry weight, then re-equilibrated in a controlled 75 per cent relative humidity atmosphere to give hygroscopic moisture content — the water the salt in that sample will hold from the air alone. Total moisture minus hygroscopic moisture is free capillary water, and it is the shape of that profile, decreasing with height, that is the standards-grade evidence for rising damp. Salt speciation on the same samples says which salts are present and where they came from. This is the method behind BS 6576, BRE Digest 245 and the Australian heritage guide, and it is the reason the 0.5 per cent salt threshold quoted elsewhere on this page is a number at all.

It is also slow, invasive and paid, and most jobs do not need it. Commission it when the finding has to survive somebody else's scrutiny: a building dispute, an insurance claim, an expert-witness matter, a contested pre-purchase decision, or a wall where competent people have looked at the same evidence and disagreed. In those cases the right call is a consultancy that investigates and does not rectify — such a practice investigates only, which is precisely what makes its findings usable in an argument. No price for that work is published here.

One thing to be plain about, because it is the standing objection to this trade and it applies to every contractor in this trade. Waterproofers both diagnose and repair. That is the normal arrangement in remedial work and it is not sinister, but it does mean the person telling you what your wall needs also sells one of the answers. So the questions are published rather than asked to be taken on faith: the six numbers above, three itemised quotes against the same written scope, the citations behind every claim on this page, and — where the stakes justify it — an investigation from someone with no rectification to sell. Where the answer to a wall is that it is a downpipe and there is no masonry work in it, that is the answer, and it is the one worth publishing.

The option with no invoice attached to it

There is a course of action that costs nothing in masonry work, and it is the one nobody advertises because there is nothing in it for the contractor.

Correct the prerequisites first — ground levels, garden beds, paving, falls, drainage, gutters, downpipes, flashings, plumbing leaks, condensate lines, wet-area membranes and subfloor ventilation. Those cost money to other trades, between $400 and $12,000 a line depending on which of them apply. Then give the wall a season before any damp course is considered.

A review stage of about twelve months is built into the Australian heritage guide's own sequence, and it is there to absorb storms, floods, drought and seasonal humidity — which in South East Queensland is not a small correction. A long dry spell looks exactly like a successful treatment. A wet season looks exactly like a failed one. Seeing the same wall through both is what separates them, and it is the cheapest evidence available to anybody.

Sometimes that stage removes the need for a five-figure treatment entirely and the masonry line on the invoice stays at zero. Often enough around here it does not, because the water table and the rain are real and the wall has no serviceable damp course — and then you arrive at the damp course conversation with the prerequisites already corrected, which is the only condition under which a chemical damp course is a good buy at any price per metre. Injecting a wall that is still being resupplied from a downpipe is money spent on a symptom.

What it costs

Questions that actually get asked

Why won't a waterproofer give me a per-metre price over the phone?

Because the per-metre rate is the smallest decision on the job and the least useful thing to settle first — and because the visit that settles the rest of it normally carries no charge, so there is nothing to be gained by guessing. Before a rate means anything, four things have to be known: whether it is rising damp at all rather than a downpipe, a leaking condensate line or a failed shower; whether one face or both faces of the wall need treating, which changes hole count and product volume; whether the ground levels allow the course to be set out 150 to 250 mm above finished ground or whether excavation comes first; and whether the wall is salted heavily enough to bring desalination at $80 to $250 per square metre into scope. All four are things you look at, on site, in about the time it takes to walk the perimeter. A number quoted before that has happened is a number that will change, and the direction it changes in is not usually downward.

Another contractor has quoted half the rate on this page. What should I ask them?

Six things, in writing: hole diameter in millimetres, hole spacing centre to centre, drilled depth relative to the wall thickness, the product name with its active silane or siloxane content and certificate, the volume of product per linear metre against the manufacturer's stated rate, and which faces of the wall are being treated. A low rate is legitimate if it reflects a genuinely smaller scope — a thin single-skin wall, external face only, no excavation, no make-good — and that should be stated on the quote rather than discovered later. The three mechanisms that produce an artificially low rate are diluting the fluid with extra solvent, spacing the holes wider than about 120 mm, and treating one side of a wall that needs both. All three are invisible from outside the wall, which is why the questions have to be asked before the work rather than after it. Ask a licensed waterproofer the same six.

Should this be priced per square metre instead?

Not the damp course. A chemical damp-proof course is a single horizontal band of treatment through the wall, so it is correctly priced by the linear metre of wall, at $120 to $400 with about eight holes in each of those metres. Several other line items genuinely are area-based and should be quoted that way: desalination at $80 to $250 per square metre, render removal at $40 to $120, replastering at $80 to $180 or $200 to $400 for heritage lime, redecoration at $40 to $90, and a Hydropoxy barrier to an internal slab at $60 to $140 per square metre. If a quote prices the injection by the square metre, ask what area is being multiplied and by what, because the answer determines the total.

Can the work be staged so we spread the cost?

Yes, and on a correctly sequenced job it is staged anyway. The prerequisites come first — levels, drainage, gutters, plumbing, subfloor ventilation — at $400 to $12,000 a line depending on which apply, and those are the highest-return dollars on the whole job. Then a season of watching what the wall does, which costs nothing. Then, if the damp is still there with the prerequisites corrected, the injection at $120 to $400 per linear metre. Then desalination and drying. Then making good, which cannot happen until the wall has dried — roughly nine months on a 230 mm wall — so it is deferred whether you want it staged or not. What cannot sensibly be staged is the diagnosis, and since it normally carries no charge there is no reason to try. Splitting it produces a scope built on half the evidence, and getting the scope wrong is the most expensive thing on this page.

Will insurance or a warranty cover any of this?

Rising damp is generally excluded from home insurance as gradual deterioration rather than a sudden event, and the answer for a specific policy is in its product disclosure statement rather than anywhere on this site. Where a concealed plumbing leak turns out to be the actual cause, the leak and its damage may be treated differently to gradual damp, which is one more reason to work out what is really happening before a claim is framed — and if the claim is going to be argued, that is one of the few situations where a forensic investigation from a consultancy that does no rectification earns its fee. Separately, building work in Queensland above a threshold commonly stated as $3,300 including materials and GST requires a licensed contractor and triggers the QBCC Home Warranty Scheme — confirm the current figure with the QBCC. A guarantee offered by a contractor is a contractual promise from that contractor, so read what voids it: blocked gutters and a garden bed rebuilt over the treated course are the two standard exclusions in this trade, and both are things that happen quietly over a few years.

How much of a typical total is actually a licensed waterproofer's work?

On the expensive worked sum on this page, $8,160 of $38,340 — just over a fifth. On the cheap one, none of it. That proportion is the honest shape of this trade, and it is why the visit normally carries no charge: there is not a lot of point charging for a look at a job that is mostly going to be somebody else's invoice. A waterproofer performs two things: a chemical damp-proof course injected into external brickwork, and an epoxy moisture barrier applied to an internal slab before new flooring at $60 to $140 per square metre. The drainage, the ground levels, the gutters, the plumbing, the subfloor vents, the desalination, the render and the paint are other trades, and they will name who does what rather than mark it up.