Paint failure warning signs on a Hobart home.
Paint does not fail all at once. It tells you it is going for a year or two first, and in Hobart it starts on the south wall where nobody looks. Learn to read five signs and you will catch the job while it is still a wash, a sand and a recoat - instead of a repaint plus carpentry.
Chalking, and the south wall problem.
Chalking. Wipe a dry hand down the north or west wall on a sunny day. Fine coloured dust on your palm means the resin binder holding the pigment has broken down under UV. Tasmania's summer UV index regularly reaches 11 or higher, and our clear air means less atmospheric attenuation than a mainland city at the same reading. A cheap acrylic starts chalking in year four; a premium system holds to seven or eight. Caught here, the job is a wash, a light sand, a binding primer and two coats - see how often Hobart exteriors really need repainting.
Mould and lichen. Black speckling, green film, or the grey-green crusty discs of lichen, always on the south elevation first. At 42 degrees south the winter sun tracks so low that a south wall gets no direct light at all, so it stays wet. This is not cosmetic: lichen puts root structures into the film and lifts it from the outside. Pressure washing it off a colonised coating often takes the paint with it, which tells you the adhesion had already gone. The older weatherboard through Glenorchy and Moonah is where we see this most.
Blistering and alligatoring - the film is telling you something.
Blistering. Cut one open. Dry inside means a heat or solvent blister from a bad application - annoying, local, fixable with prep and recoat. Wet inside means water is coming from behind and you have a building problem, not a paint problem. The usual Hobart sources: a gutter overflowing onto a wall, ground moisture wicking up a bottom board never sealed underneath, a failed flashing at a window head, or bathroom humidity pushing out through a wall with no vapour path. Recoat without finding the source and the blister returns in the same spot within two winters. Every time.
Alligatoring. A network of cracks across the surface that looks like reptile skin, most often on old enamel over trim, fascias and window frames. It means the coating has lost its flexibility, so it can no longer move with the timber underneath as it expands and contracts, and the film splits into islands instead. Usually it is a hard, brittle coat applied over something softer, or simply too many coats built up over decades without anyone ever taking it back. There is no recoat answer to this one: paint over alligatoring and the pattern telegraphs straight back through the new film within a season, because the cracks are structural to the coating rather than on top of it. It has to come back to a sound surface. On anything pre-1970 that means a lead swab first, at 280 to 480 dollars, and controlled preparation under AS 4361.2 rather than a sander on an extension lead.
Rust bleed - and where salt makes it worse.
Rust bleed. Fine orange-brown tears running down a weatherboard from each nail head are the common version, and they are usually a preparation story rather than a structural one: the head was never spot-primed before the last repaint, or the galvanising on it has simply given up after forty years. That is a straightforward fix. We punch the head below the surface, treat it, spot-prime it with the right metal primer and fill over it before the wall gets its coats. Do it in the recoat and it is minutes per head. Ignore it and the stain keeps coming back through every new topcoat you put on, because the source is under the film, not on it.
Broader rust staining around window frames, roof edges, fascias and gutters is a different animal. That is active corrosion, and paint is not a treatment for it. On river-facing elevations, salt-laden air off the Derwent accelerates the process markedly - the eastern shore, Sandy Bay, Taroona and Blackmans Bay all see it on exposed steelwork and older window hardware. Painting over active corrosion hides it for about a year, then it comes back through and you have paid for nothing. When it is roof steel, that decision sits alongside the bigger question in our roof paint versus restoration guide.
What the delay actually costs.
A single-storey 1965 weatherboard in Moonah, roughly 165 square metres of external wall, last painted in 2018.
Acted on at the chalking and light-mould stage, 2026. Biocidal treatment wash, light sand, binding primer on the chalked north and west, mould-inhibiting two-coat system throughout. At 45 to 85 dollars per square metre that is roughly 7,400 to 14,000 dollars, inside the normal 8,500 to 14,500 dollar band. No carpentry. One visit.
Left until 2030. Same wall area, but now with lichen-driven adhesion failure across the south, breached film on the west, and bare timber cycling wet and dry for four winters. Add lead swab testing at 280 to 480 dollars, controlled lead-safe removal over the failed areas at 45 to 95 dollars per square metre, and carpentry for the boards that have gone. Realistically 18,000 to 26,000 dollars and two trades instead of one. Same house, same paint - the only variable is the four years. Full bands on the pricing guide; the work runs through our exterior house painting process.
Common questions about paint failure in Hobart.
What are the first signs my Hobart exterior paint is failing?
Run your hand down a sunny wall. If it comes away with fine coloured powder, that is chalking - the resin binder has broken down under UV. On the shaded side the first sign is black or green speckling, which is mould and lichen on a surface that never dries. Both give you 12 to 24 months of lead time. Act inside that window and it is a wash, a sand and a recoat. Miss it and the job doubles.
Why does the south side of my Hobart house always fail first?
At 42 degrees south, a south-facing wall receives essentially no direct sun through midwinter. It gets wet from wind-driven rain and dew and then simply does not dry. A north wall dries within hours of a shower; a south wall can stay damp for days. Mould and lichen need exactly that, so they colonise the coating and their root structures lift the film from the outside in.
What does paint blistering on a Hobart weatherboard actually mean?
Water is behind the film, and the question is where it came from. Blisters that are dry when you cut one open are usually heat or solvent blisters from a bad application. Blisters that are wet inside are moisture blisters - a failed flashing, a gutter overflowing onto the wall, ground moisture wicking up an unpainted bottom edge, or interior humidity with no vapour path. Recoating without finding the source is the most common waste of money in this trade.
How long can I leave failing paint before it costs me more?
Roughly two Hobart winters from first breach of the film to substrate damage, and shorter on an upward-facing surface like a window sill. Once the film is breached, water reaches bare timber and the timber cycles wet and dry. Two years of that needs filling and sanding; five years needs boards replaced. Chalking is a warning. Flaking is a deadline.
Is rust bleeding through my paint a paint problem or a bigger problem?
Small rust stains running from nail heads are usually a prep issue - the head was not spot-primed, or the galvanising has given up. We punch, treat and spot-prime before recoating. Larger staining around window frames, roof edges or anything river-facing is corrosion, and paint is not the answer to it. Salt off the Derwent accelerates this on exposed elevations. Paint over active corrosion and you are hiding it, not stopping it.
Free inspections across Greater Hobart.
Seen something on your walls? Get it read properly.
Chalking, mould, blistering or rust bleed. We will tell you what it is, how long you have, and whether it is a paint job or something else.