Southern Tasmania
Rising Damp Hobart connects owners of Georgian, Victorian and Federation homes with damp specialists across southern Tasmania. Salt bloom on a sandstone wall, paint lifting above the skirting, a musty room that never quite dries — we arrange the assessment that tells you what is actually happening.
Six things Hobart homeowners describe when they ring. Any one of them is worth metering; two or more together usually means the wall is drawing moisture out of the ground.
Salt carried up out of the masonry and left behind when the water evaporates. On sandstone it often comes with the surface crumbling away behind it.
Rising damp has a ceiling — the height where evaporation balances the water being drawn up. A stain that stops in a fairly level line is the classic sign. Water coming from above does not do that.
Bubbling, blistering or a chalky powder when you rub it. The wall is pushing moisture and salt outward through the finish.
Run a key along a joint. If it powders away, salt has been working in it for a long time.
The face of the stone flaking or dishing out. Common on Hobart's older stock and the most expensive symptom to leave alone.
Especially a south-facing room in winter. Worth checking whether it is rising damp or condensation, because the fix is completely different.
It is not the amount of rain. Hobart records about 611.0mm a year, which is less than Brisbane. The difference is that it falls in every month and there is very little sun to drive it back out again.
| Month | Rainfall | 9am humidity | Sun per day |
|---|---|---|---|
| January | 46.3 mm | 60% | 8.0 h |
| May | 47.4 mm | 76% | 4.2 h |
| June | 53.6 mm | 79% | 3.9 h |
| July | 51.9 mm | 78% | 4.4 h |
| August | 54.0 mm | 73% | 5.0 h |
| October | 62.0 mm | 63% | 6.5 h |
Source: Bureau of Meteorology station 094029, Hobart (Ellerslie Road). Annual rainfall 611.0mm across 86.8 days of rain of 1mm or more.
Nine in the morning through May, June and July sits at 76 to 79 per cent humidity, with under four hours of sun a day in June. A wall that takes up moisture in May has until roughly September before it gets a real chance to give it back. On the mainland a wet season is followed by hot dry months that dry the masonry out. Here it simply carries on.
Every figure in that table is the Bureau of Meteorology thirty-year average for station 094029, not our estimate. It is worth stating plainly, because Hobart is often described as a rainy city and the numbers say something more useful than that: not much rain, spread across every month, with little sun and cold walls.
The right treatment depends almost entirely on the era and the construction, and Hobart has three broad groups.
Battery Point, central Hobart and pockets of New Town. Solid masonry laid on rubble or slate footings, built decades before a damp proof course was a normal thing to install. There is no cavity, so moisture that enters the base of a wall has nowhere to go but up and inward.
North Hobart, Sandy Bay, South Hobart. Many do have an early damp proof course — slate, bitumen felt or lead — and most of those have failed, cracked or been bridged by later rendering, paving or a garden bed built up against the wall.
Moonah, Glenorchy, Lenah Valley, Bellerive. These generally have a working DPC. When damp appears here it is usually bridged rather than absent — a path has been built across the course rather than the course itself failing.
The methods, what each one suits, and the questions people ask before they spend anything.
Installing a damp proof course into a wall that never had one, or replacing one that has failed.
DPC injectionLevels, drainage, barriers and replastering — and why the order of the work decides the cost.
Damp proofingWater pressing through a wall sideways on a sloping block. Very common in Hobart and often misdiagnosed.
Lateral dampWhy the white bloom appears, and why sealing or cement-pointing stone makes it worse.
Sandstone frettingWhen Heritage Council approval is needed before works, and what tends to be questioned.
Heritage homesBoth are common in a Hobart winter, they look similar, and the fixes have nothing in common.
Telling them apartWhat to look for before you exchange, and what a building report will and will not tell you about damp.
Pre-purchase dampFor the suspended-floor stock. Much of Hobart's oldest housing has no subfloor at all.
Subfloor ventilationWhat the health question actually turns on, and which of the two problems you are likely to have.
Damp and mouldWhat the May 2018 flash flood left in the ground, and how to check the flood mapping for your own address.
Flood legacy dampStep 1
Someone comes to the property, meters the walls at several heights, checks ground and paving levels against the internal floor, and looks for the bridge or the failed course. Free, and no obligation.
Step 2
You get told what it is before anyone quotes a repair — including when it turns out to be condensation, a leaking downpipe or a failed shower rather than rising damp.
Step 3
If the property is on the Tasmanian Heritage Register or in a heritage precinct, that gets established before any method is proposed. It changes what is allowed.
Step 4
One price for the scope, with the exclusions listed plainly.
Step 5
Injection, replastering, drainage or stone repair as diagnosed, by the trade best suited to that method.
Step 6
A treated wall does not look better immediately. Masonry gives moisture back slowly — allow months, not weeks, and expect the replastering to be a second visit.
Rising damp has a ceiling — a tide mark that stops in a fairly level line, usually under a metre and a bit. Condensation appears on cold surfaces, often in corners, high on walls and around windows, and it is worst in winter in rooms that are not ventilated. In Hobart both are common and they can occur together, which is exactly why a meter reading beats a guess.
Usually yes, but the method has to be approved. Works to a registered place need Heritage Council approval — either a certificate of exemption where the impact is negligible, or a development application. Chemical injection of masonry is specifically addressed in Heritage Tasmania's Works Guidelines. Establish that before anyone drills anything.
It makes it more visible and more urgent. Sandstone is porous and draws moisture readily, and the salt left behind crystallises inside the stone and pushes the face off. That is the fretting you see on older Hobart walls. Brick tolerates the same conditions for far longer before it shows.
It is not the amount of rain. Hobart gets about 611mm a year, less than Brisbane. It is that rain falls in every month and there is almost no drying — 9am humidity sits at 76 to 79 per cent from May to July and there are under four hours of sun a day in June. A wall that takes up moisture in May has until roughly September before it gets it back out.
Often not by itself. If the ground outside is higher than the floor inside, or paving bridges the wall, or a garden bed has been built against it, the water has a path around any course you install. Ground levels and drainage get corrected first or the injection is wasted money.
Months. Masonry releases moisture slowly and salt keeps coming out of the plaster while it dries. Replastering is normally a separate later visit for that reason. Anyone promising a finished wall in a fortnight is telling you what you want to hear.
No. Rising Damp Hobart is a referral service — we arrange the assessment and connect you with damp specialists and licensed trades in southern Tasmania. The work and the warranty come from them.
We cover Hobart and the surrounding suburbs, from the Georgian cottages of Battery Point to the post-war brick of Glenorchy and Moonah.
Someone comes out, meters the walls, looks at the ground levels and tells you what is causing it. You get that in writing before anyone quotes a repair.