Fixing rising damp: finding the right specialist for the job

How rising damp treatment works, why diagnosis matters more than the injection, and the warranty and re-plastering questions to ask every quoter.

A wall surface being repaired and re-rendered

Bubbling paint, crumbling plaster, a tide mark creeping up the wall, that unmistakable musty smell — rising damp announces itself slowly and then becomes the only thing you can see in the room.

The fix is well established, but this is a category where the diagnosis matters more than the treatment — because a lot of what gets sold as rising damp is actually something cheaper to fix.

What damp proofing involves

True rising damp means moisture wicking up from the ground through the wall because the original damp-proof course has failed or been bridged. The standard fix is a new chemical damp-proof course: holes drilled along the base of the wall, injection cream inserted, forming a continuous moisture barrier. It's priced per linear metre of wall, and wall construction matters — double-brick and stone walls take longer to drill and more product than single-skin brick.

Treating the wall is often only half the job. Damp carries salts up into the plaster, and salt-contaminated plaster keeps drawing moisture from the air even after the wall below is fixed. It usually needs hacking off and replacing with a renovating render — after the wall has had weeks to months to dry.

Crucially, not all damp is rising damp. Condensation, leaking pipes, failed shower waterproofing, blocked subfloor vents and garden beds piled against walls all mimic it. Those problems have their own, often cheaper, fixes — and injecting a wall doesn't solve any of them.

What treatment tends to cost

A single affected wall sits in the low thousands; several walls with re-plastering afterwards lands in the middle thousands; whole-home perimeter treatment of an older double-brick house runs toward five figures. Indicative only — the calculator on this page adjusts for your metres and wall type.

The re-plastering line deserves attention when comparing quotes: it can cost as much as the injection itself, and quotes differ on whether it's included at all. A cheap quote that treats but doesn't re-plaster isn't comparable to one that does both.

Choosing a damp specialist

Damp proofing isn't a licensed trade in most of Australia, so your protections are diagnosis quality and warranty. The best money you can spend is on an independent assessment first — someone with a moisture meter and no injection product to sell. If a company diagnoses rising damp in every house they visit, that tells you something.

On warranty: quality damp-course systems commonly carry written warranties of ten to twenty years. Get it in writing, with the product system named, and check whether the warranty is backed by the installer, the manufacturer, or both. A specialist who talks about drying time before re-plastering, and about fixing the cause (drainage, bridged courses, ventilation) rather than only injecting, is showing you they understand the whole problem.

Mistakes to avoid

Damp is a category with real information asymmetry — the wall can't tell you what's wrong, so process is your protection.

Accepting a rising damp diagnosis from someone selling rising damp treatment, without a second opinion
Treating the wall while ignoring the cause — garden beds, drainage or leaking pipes against it
Re-plastering too soon after treatment, trapping moisture the wall was trying to release
Comparing quotes without checking whether re-plastering is included
Accepting a verbal warranty — get the years, the product system and the backer in writing
Painting over damp with 'sealer' paint as a fix — it hides the symptom and worsens the wall

What does it cost?

$500 – $12,000most jobs land around $3,500

Indicative range only, not a quote — see the full guide for worked scenarios and what moves the price.

Damp Proofing cost guide →Find damp proofing near you