Here are the published ranges, and what moves a job within them.
Talk it throughRising Damp Perth assesses and treats damp across the Perth metropolitan area.
Nobody can price a damp treatment properly over the phone, because the cost is set by what the wall is made of and how much salt is already in it. A single-skin limestone wall, a double-brick cavity wall and a rendered wall of either are three different jobs. What we can give you is an indicative range to budget with before anyone visits.
The figures below are indicative budget ranges, not quotes, and the note under the table says how they were set. Limestone takes injection differently to brick and usually needs more of it, and any wall carrying years of salt needs the render taken back and replaced with something that lets it breathe. That replastering can be where most of the money goes.
Two things move a Perth quote more than anything else: whether the wall is limestone or brick, and whether someone has already sealed it with a cement render or a plastic paint. Undoing a well-meant repair is real work, so the honest range is wide.
Prices here assume ground-floor work on an accessible wall. Heritage listing, a shared party wall, or a floor that has to come up will all move the number. You get a fixed figure after we have looked at it.
What follows is indicative. Every one of these is a range because the wall decides, not the website.
| Work | Indicative range | What it covers |
|---|---|---|
| On-site assessment and written diagnosis | $450 plus GST | Moisture readings across the affected walls, a look at ground levels and drainage, and a written finding on which of the five common causes you actually have. |
| Chemical damp-proof course, per metre | $180 - $340 | Injected into the mortar course. Limestone generally sits at the upper end because it takes more material to achieve a continuous barrier. |
| Salt-retarding replaster, per square metre | $120 - $260 | Old contaminated render off, breathable system on. Can be the larger part of the job. |
| Drainage and ground-level correction | $900 - $6,000 | Lowering paving, cutting back garden beds, adding a drain. Where the cause is bridging rather than a failed damp course, this is the fix. |
| Subfloor ventilation improvement | $1,200 - $4,500 | Much newer Perth housing sits on a slab or on solid footings rather than over a ventilated subfloor, so this applies mainly to the older timber-floored stock. |
Prices are indicative ranges only. Limestone, double brick and rendered walls each cost differently to treat, and every fixed price follows an on-site assessment.
How these figures were set: the $450 plus GST assessment is the one fixed price, set on 8 September 2026. The treatment ranges were entered when the site was built in August 2026 and have not yet been checked against written quotes for Perth jobs, so treat them as a budget guide only.
Limestone is more porous and takes more material to form a continuous barrier. Expect the upper end of the per-metre range.
Replastering can be the larger half of the bill. A wall caught early may need very little of it.
Cement render or plastic paint has to come off. Removing a previous well-meant repair is real work.
If lowering paving or a garden bed is the whole fix, only the drainage and ground-level row applies.
A listed facade in Mount Lawley or Fremantle limits what can be cut or drilled, and a shared party wall in Highgate means a conversation with a neighbour before a quote is even meaningful.
You can buy the kit. The reason it usually fails is that the diagnosis was wrong, or the salt already in the wall was never removed, so the tide-mark returns through the new plaster. The chemical is the cheap part.
We carry out assessments across the Perth metropolitan area, including:
Rising Damp Perth