Rising damp is groundwater climbing a wall. Everything else — the salt, the lifting paint, the smell — follows from that one fact.
Talk it throughRising Damp Perth arranges damp assessments across Perth metropolitan area.
Perth's older suburbs are built from what was underneath them. Limestone quarried locally went into Fremantle, Cottesloe and Claremont; double brick took over from about the 1900s and still dominates the inner ring. Both are porous, both sit on sand, and a great many of them were laid with no damp-proof course whatsoever — the practice did not become routine here until well after the Second World War.
Sand drains beautifully until it does not. Through a Perth winter the water table under the older river and coastal suburbs rises close to the surface, and a wall standing in damp sand behaves like a wick. The moisture climbs until the rate it evaporates from the wall face matches the rate it arrives, which is what sets the height of the tide-mark.
Salt is the second half of it. Groundwater carries dissolved salts up into the wall and leaves them behind when the water evaporates. On the coast, more salt arrives on the wind. Those crystals expand as they form, and that is what blows render off limestone and crumbles the face of a brick — the water moves it, but the salt does the damage.
Perth gets about 733mm of rain a year across roughly 112 days, and almost all of it falls between May and September. That concentration is the whole problem. A wall spends four months taking up groundwater faster than it can release it, then eight months drying out — so the damage builds every winter and appears to heal every summer. Owners repaint in January, and by August the tide-mark is back.
An even horizontal line, roughly 600mm to 1.2m above the floor, on a ground-floor wall. It marks where the water stops climbing and starts evaporating. Condensation does not produce a level line like this.
Salts left behind as the water evaporates. On limestone it often looks like a fine bloom; on brick it can be gritty. Brushing it off works until the next winter.
Almost always a non-breathable coating applied over a wall that needs to dry outward. The coating is not failing — it is doing its job and trapping the moisture behind it.
Salt crystallisation forcing the surface apart. Common on the coastal limestone belt and usually well advanced before anyone calls it damp.
Bore water. Perth's reticulation draws iron-rich groundwater, and where it hits a wall the iron stains it. It is not rising damp, it is cosmetic, and it is worth knowing before you pay to treat the wrong thing.
Seasonal is the tell. A leak smells the same all year; rising damp tracks the water table.
The order matters. Injecting a damp course into a wall whose real problem is a paved garden bed is money spent on the wrong thing, which is why the assessment comes first and the quote comes after.
Moisture meter readings at height intervals up the wall, an external check of ground levels, paving and reticulation, and a look at what coatings are already on the wall.
Rising damp, lateral damp through a retaining or buried wall, a plumbing or reticulation leak, condensation, or bore-water staining. They look alike and cost very differently.
If paving has buried the damp course or a garden bed sits against the wall, that is corrected before any chemical course is considered. Injecting around a bridge does nothing.
A chemical course injected into the mortar line, sized to the wall material.
Contaminated render removed and replaced with a salt-retarding, breathable system. Skipping this is why treated walls come back.
A treated wall dries over months, not days. Anyone promising a finished wall in a fortnight is telling you what you want to hear.
We arrange assessments across the Perth metropolitan area, including:
Rising Damp Perth