Hobart has the oldest housing stock of any Australian capital. Georgian and Regency sandstone and brick cottages from the 1820s, 1830s and 1840s still stand in daily use in Battery Point, central Hobart, West Hobart and South Hobart — buildings that predate Federation by three generations and predate almost everything standing in Melbourne, Brisbane or Perth. They are extraordinary, they are habitable, and they are routinely damaged by people who renovate them as though they were built in 1975.
A related guide to consider while planning this work is Heritage and Character Controls in Hobart: Renovating Without Getting Stuck.
The single most important thing to understand is that a colonial cottage is not a modern building with old finishes. It is a fundamentally different construction system with different physics. It manages water by absorbing and releasing it rather than by draining a cavity. Its mortar is deliberately weaker than its stone. It has no damp-proof course and was never intended to have one. It breathes, and every modern instinct — seal it, waterproof it, insulate it tight, point it in something strong — makes it worse.
Get that right and these houses are warm, dry and worth a great deal of money. Get it wrong and you will spend $300,000 producing salt damp, spalling sandstone and mould behind plasterboard.
What these buildings actually are
Hobart’s early stock is generally sandstone, soft handmade brick, or a combination — sandstone quoins and brick infill is common — built by convict and colonial labour with the materials that were to hand. The characteristics that matter are consistent across the type.
- Solid masonry with no cavity. Walls of 350–600mm, often two skins of stone or brick with a rubble core. There is no drainage plane, no weep holes and no cavity ties. Water that enters is dealt with by evaporation.
- Lime mortar. Soft, permeable, and intentionally weaker than the masonry units. Movement, salt crystallisation and moisture damage occur in the joint — the sacrificial element — rather than in the stone.
- Rubble stone footings. Often a shallow trench of stone with no reinforcement and no spread footing in the modern sense. Bearing capacity is variable and rarely what an engineer will assume.
- No damp-proof course. There is nothing between the ground and the wall. Moisture rises and leaves through the wall face. That is the design.
- Timber floors on log or stone bearers. Ground floors are frequently suspended timber over a shallow, poorly ventilated subfloor. Bearers may literally be squared logs bedded into the earth.
- Lath and plaster on internal walls and ceilings — timber lath with a lime or lime-gypsum plaster, sometimes with horsehair reinforcement.
- Single glazing in timber sashes, often with original cylinder or crown glass, and glazing bars far finer than any modern replacement.
- Generous ceiling heights in the main rooms, low in the service wing, and floor levels that step because the ground did.
How this differs from later stock
- Victorian and Federation houses from the 1880s onward increasingly have cavity walls, a slate or bitumen damp-proof course, and cement content in the mortar. Everything you can safely do to a 1905 cottage may be actively harmful to an 1835 one.
- Post-war brick veneer has a structural timber frame and a non-structural skin. A colonial wall is the structure. You cannot open it up casually.
The cement mortar problem
This is the single most damaging mistake made to Hobart’s early housing stock, it is made constantly, and it is usually made by well-meaning people who thought they were maintaining the building.
A related guide to consider while planning this work is How Much Does a Home Renovation Cost in Hobart? A 2026 Price Guide.
Colonial sandstone and soft handmade brick are permeable. So is lime mortar. Water enters the wall — from the ground, from driving rain, from a leaking gutter — and leaves again primarily through the mortar joints, which are the softest and most permeable part of the wall assembly. Dissolved salts travel with that moisture and crystallise where the evaporation happens. Because that is in the mortar, the mortar erodes over decades and gets repointed. That is normal, expected maintenance, and it is why lime mortar is described as sacrificial.
Now repoint that wall in modern cement mortar. Cement is harder and far less permeable than the stone. The evaporation path through the joint closes. The moisture still enters, so it now has to leave through the only remaining route: the face of the stone or brick itself. Salts crystallise a few millimetres behind the surface, and the crystallisation pressure blows the face off.
- Sandstone spalls and delaminates, shedding the outer layer in sheets and leaving a soft, eroding face that keeps retreating.
- Soft handmade brick loses its fired outer skin and then erodes rapidly, because the interior of the brick is far softer than the surface.
- The cement joints survive intact and end up standing proud of the eroded masonry — the classic visual signature of the damage, visible on hundreds of Hobart buildings.
- The damage is permanent. You cannot put the face of the stone back. You can only cut out the cement, repoint correctly, and stop it getting worse.
- Cement render over colonial masonry does exactly the same thing, over the entire wall at once, and is worse.
Doing it properly
- Lime mortar repointing costs $120–$280 per square metre of wall face — more than cement, and worth every dollar.
- Rake out by hand to a depth of roughly twice the joint width. Angle grinders widen joints, damage arrises and cause more harm than the failed mortar did.
- Match the mix to the masonry — the mortar must be weaker than the stone. A specifier should assess the existing mortar and the masonry hardness rather than defaulting to a standard mix.
- Match the joint profile to what survives elsewhere on the building. Flush or slightly recessed is usually correct; a weather-struck cement joint is not.
- Protect and cure. Lime work needs protection from sun, wind, rain and frost while it carbonates, which materially limits the Hobart season. Realistically that means late spring to early autumn.
- Removing existing cement pointing is slow, careful, expensive work — and it is often the highest-value repair you can do to one of these buildings.
Rising damp, honestly
Almost every colonial cottage in Hobart has damp at the base of its walls, and almost every owner is offered a chemical injection system as the solution. The honest position is that damp in a solid rubble wall is a moisture-balance problem, not a product problem, and it is fixed by changing the balance.
What actually works
- Fix the water first. Blocked or missing gutters, downpipes discharging at the wall base, cracked stormwater, and a driveway falling toward the house cause more “rising damp” in Hobart than capillarity ever did.
- Lower the external ground level. A century and a half of accumulated soil, garden beds and successive paving layers frequently sit 200–400mm above the internal floor, bridging moisture straight into the wall. Cutting the ground back below floor level is the single most effective intervention available.
- Remove impermeable paving against the wall. Concrete and cement-bedded pavers up to the masonry trap ground moisture and force it into the building. Replace with a permeable margin — free-draining gravel, or paving laid on sand and falling away.
- Install a French drain or agricultural drain on the uphill side. On Hobart’s slopes, most damp in the rear wall is groundwater moving downhill through the site, not water rising from below.
- Ventilate the subfloor properly. Clear and add vents, remove the accumulated rubble and soil that blocks cross-flow, and make sure air can actually move from one side of the building to the other.
- Use breathable finishes internally. Lime plaster and mineral or lime-based paints let the wall dry inward. Cement render, acrylic paint, plastic membranes and foil-backed board seal the wall and drive the moisture higher.
- Accept a managed equilibrium. A properly drained, ventilated, breathable colonial wall will still hold some moisture at the base. The goal is a dry, salt-free, healthy interior — not a moisture meter reading of zero.
On injection systems
Chemical damp-proof course injection is designed for a homogeneous wall of known thickness. A rubble-cored colonial wall is neither. The injected fluid follows voids and preferential paths rather than forming a continuous barrier, and in a 500mm rubble wall a continuous chemical DPC is very difficult to achieve. Injection is often sold with a re-render in a strong cement mix, which then compounds the problem by sealing the wall face. If you are considering it, ask specifically how a continuous barrier will be achieved through a rubble core, and what the internal finish specification is. If the answer to the second is cement render, walk away.
Interstitial condensation: why you must not seal the wall from inside
Hobart is Australia’s coldest capital and condensation and mould are the defining building-performance problem in Tasmania. The instinct with a cold solid masonry wall is to line it internally with insulation and plasterboard. Done wrongly, this is the fastest way to destroy the building.
- Adding internal insulation makes the masonry colder, because it no longer receives heat from the room. Colder masonry dries more slowly and holds more moisture.
- Warm, moist internal air reaches the cold face of that masonry behind the lining and condenses inside the wall assembly, where you cannot see it and it cannot dry.
- The result is rot in embedded timber — lintels, bond timbers, joist ends and battens — plus mould growth in the concealed cavity and salt migration in the masonry.
- Never use closed-cell foam, foil-faced board or a vapour barrier against the inside face of a solid masonry wall.
- Where internal insulation is genuinely needed, use a vapour-open, capillary-active system — wood fibre, lime-hemp, or a breathable mineral board bedded in lime — specified by someone who has done it before, and keep it modest in thickness.
- Do the low-risk things first. Ceiling insulation at $2,200–$6,000 and draught sealing at $1,500–$4,500 deliver the biggest comfort gain in these houses with none of the risk.
- Underfloor insulation at $2,800–$7,500 is high value, provided subfloor ventilation is maintained or improved at the same time.
- Ventilate deliberately. Extract fans ducted to outside, not into the roof. Colonial houses were ventilated by their own leakiness; when you seal them, you must replace that with controlled ventilation.
Glazing without wrecking the windows
- Original timber sashes with early glass are among the most significant surviving elements of these houses, and replacing them with aluminium is both a heritage failure and usually a planning refusal.
- Repair the sashes — splice the rot, re-cord the weights, re-putty, draught-seal the meeting rails and stiles. A well-restored, draught-sealed sash performs far better than an unrestored one.
- Secondary glazing over the existing sash at $450–$1,000 per square metre is the standard heritage answer. It delivers most of the thermal and acoustic benefit, is reversible, and is usually approvable where replacement is not.
- Thermally broken double glazing at $1,300–$2,400 per square metre is appropriate in new rear additions, where it returns more in Hobart’s climate than in any other Australian city.
What to keep and what to let go
- Keep: the street elevation and its proportions, original masonry and its unpainted finish, timber sashes and doors, chimneys and fireplace openings, original roof form, joinery, skirtings and architraves, and any surviving lath and plaster in good condition.
- Keep and repair rather than replace: floorboards, cast iron, original hardware, and the shape and volume of the principal rooms.
- Let go: the 1960s lean-to, aluminium windows added in the 1980s, cement render applied to hide previous damage, bagged and painted chimneys, and internal bathrooms cut into good rooms with no ventilation.
- Let go without guilt: the idea that every room must be restored to a single period. These houses have been altered continuously for 190 years; a good renovation adds a legible, honest layer rather than a fake one.
Heritage approvals
Three distinct levels apply in Hobart, and they stack rather than replace one another.
- Local Heritage Place — an individually listed property under the Tasmanian Planning Scheme via the Hobart Local Provisions Schedule. Planning approval is required for any use or development of the site.
- Local Heritage Precinct — an area listing, of which Battery Point is the best known, with other precincts covering parts of central, North, South and West Hobart, New Town and Sandy Bay. Again, planning approval is required for use or development of the site.
- Tasmanian Heritage Register — listing under the Historic Cultural Heritage Act 1995, where proposals are referred to the Tasmanian Heritage Council (1300 850 332) as well as requiring council planning approval. This is the state-level tier and applies to the more significant colonial buildings.
- Check your own address against the Hobart Local Provisions Schedule heritage overlay maps and with the Tasmanian Heritage Council. Do not assume from your neighbours’ experience — listings vary property by property.
- A heritage-triggered application is discretionary, is advertised for 14 days, can attract representations, and pushes the building work into Category 4 permit work requiring a formal building permit from council in addition to building surveyor certification.
- Listing does not prevent change. The City of Hobart’s own position is that modifications are assessed so that heritage characteristics are not lost — not that nothing may happen.
The order of operations
Sequence matters more in these buildings than in any other stock, because several of the steps are irreversible and several depend on drying time.
- 1. Investigate. Building inspection, timber pest inspection, an asbestos survey ($400–$900) for later fabric, a structural opinion on footings and walls, and where the site is steep or mapped, a geotechnical or landslip report ($3,500–$12,000).
- 2. Stop the water. Roof, gutters, downpipes, stormwater, ground levels, drainage, subfloor ventilation. Nothing else should start until this is done.
- 3. Let it dry. A wall that has been wet for decades needs months, sometimes a full year, to reach equilibrium. Plastering too early destroys the new work.
- 4. Structure. Restumping or re-levelling ($14,000–$38,000), lintels, cracked masonry repair, floor framing.
- 5. Masonry repair and repointing in lime, in the warmer months.
- 6. Services. Full rewire and switchboard ($9,000–$17,000), plumbing, and heating — chased carefully, because every chase in a solid wall removes structure.
- 7. New work. The rear addition, articulated and recessive, with its own footing system detailed to allow differential movement.
- 8. Linings and finishes. Breathable plaster, mineral paints, joinery repair.
- 9. Thermal and comfort work. Ceiling and underfloor insulation, draught sealing, secondary glazing, heat pump.
- 10. Externals. Paving, drainage falls, landscaping and fencing — completed last, and detailed so they never trap water against the walls.
Realistic costs
- Cosmetic to mid-level whole-house renovation: $2,000–$3,400 per square metre
- High-end restoration: $3,800–$6,500 per square metre, and colonial fabric sits at the top of that band
- Lime mortar repointing: $120–$280 per square metre of wall face
- Restumping or re-levelling: $14,000–$38,000
- Full rewire plus switchboard: $9,000–$17,000
- Re-roof in Colorbond: $13,000–$28,000; slate or heritage roofing considerably more
- Kitchen: $30,000–$50,000 mid-range, $65,000–$150,000 at the high end
- Bathroom: $32,000–$48,000 mid-range, $58,000–$95,000 at the high end
- Secondary glazing: $450–$1,000 per square metre
- Building surveyor: $2,500–$8,000; architect 8–12% of build cost
- Asbestos removal where later fabric is involved: $2,500–$15,000
- Contingency: 20% on any colonial building. What is behind the plaster is unknown until it is open.
What these houses are worth done well
Properly renovated colonial cottages are the most sought-after housing in Tasmania, and Battery Point in particular supports values that will absorb almost any sensible spend. But the market is discerning in a way it is not for a renovated 1970s brick veneer. Buyers at this level, and their inspectors, know what cement pointing means. They know what a bagged-and-painted stone wall is concealing. They can tell a repaired sash from a replacement, and they price accordingly.
The premium goes to houses where the old fabric has been conserved and the new work is confident and clearly of its own time — a warm, dry, well-serviced house that still reads as an 1830s building. The discount goes to houses that have been made superficially smart and fundamentally damp.
Broader benchmarks for a project like this sit in the 2026 Hobart renovation price guide, and the approval framework in the 2026 council approval rules. If a rear addition is part of the plan, the construction economics are set out in the guide to Hobart extensions; for the listing tiers and what gets approved, read heritage and character controls in Hobart. Given how much of this work is specialist, finding and vetting the right builder is the decision that determines the outcome.
A view on colonial renovation
These buildings have survived nearly two centuries in a cold, wet climate without insulation, without a damp-proof course and without maintenance for long stretches. They are not fragile. What makes them fragile is being sealed — pointed in cement, rendered in cement, painted in acrylic, lined in foil-backed board, and paved right up to the walls. Every one of those interventions was done by someone trying to keep water out, and every one of them keeps water in.
The best advice anyone can give a Hobart colonial owner is to think in terms of drying rather than sealing. Give the wall a path for water to leave and a reason not to arrive in the first place, and the building will look after itself for another 190 years.
Find people who have done this work before — a designer, a surveyor and a mason who can talk fluently about lime and know why it matters. There are not many of them in Tasmania and they are busy. Wait for them.