Guide
Tired paint, or a weathertightness problem?
Some houses do not need painting. They need investigating, and painting them makes the next owner's problem more expensive and harder to see. This is how to tell which one you have before you spend money on the wrong trade.
42,000
Dwellings estimated to be affected by weathertightness failure in the national estimate — at an estimated total cost of $11.3 billion. These are 2009 estimates for the 1992–2005 build period, not a prediction about any one house.
The signs
What a tired coating looks like, and what water looks like
Neither list is diagnostic on its own. Together they tell you whether the next call is a painter or a building surveyor.
Consistent with a coating at the end of its life
- Chalking — a fine powder transfers to a dry hand, evenly, across a whole elevation.
- Fading and loss of gloss, worst on the north and west faces where the sun is.
- Fine crazing or checking in the coating itself, not in the substrate.
- Flaking that follows exposure — sills, ends of boards, the weather side.
- Mould and lichen on the surface, washing off to sound paint underneath.
Consistent with water getting in
- Blistering or peeling in a defined patch rather than across an elevation — especially below a window, a junction, a deck, a balustrade or a penetration.
- Staining, rust marks or discolouration tracking downwards from one point.
- Timber that is soft to a probe, or fixings that have rusted out.
- Cracks in a monolithic or plaster cladding, particularly at sheet joints and around openings.
- Interior signs on the same wall: a musty smell, swollen skirting, lifted flooring, mould in a corner that keeps coming back.
- A repaint that failed within a couple of years in the same place.
What the data says
The split by cladding type was not marginal
When New Zealand’s weathertightness failures were costed for the Department of Building and Housing, the difference between cladding types was the whole story. It is the reason a monolithic house should be investigated before it is quoted.
Read that carefully: it is an estimated failure rate for a build period, not a probability for your address. A monolithic-clad house that was detailed and maintained well may be perfectly sound, and a weatherboard house with a bad deck junction may not be. What the split justifies is the order of operations — investigate first on a monolithic or plaster-clad building, then paint.
It also explains why one rate per square metre cannot cover both. What each cladding type actually needs, and how that changes an exterior repaint.
BRANZ Study Report SR142, House Condition Survey 2005 · 2005
PwC for the Department of Building and Housing, “Weathertightness — Estimating the Cost” · 2009
What to do
The order that saves money
- 01
Photograph the pattern, not the wall
Close-ups of each failure, wide shots showing where it sits on the elevation, and the interior of the same wall. The pattern is the diagnosis; a photo of a whole house is not.
- 02
Get moisture readings before you get quotes
Non-invasive first, invasive where the readings justify it, from a building surveyor or a suitably qualified building professional — not from whoever is quoting the paint.
- 03
If it is water, fix the cause and then the coating
Flashings, junctions, seals, cladding repair. Where that is restricted building work under the Building Act 2004 it must be carried out or supervised by a Licensed Building Practitioner. It is a genuinely different job — that is a recladding conversation.
- 04
If it is the coating, then paint it properly
And expect the preparation to be most of the price, because on a surface at the end of its life it is. What that consists of.
Questions people actually ask
Will painting stop a leak?
No. Paint is a protective and decorative coating, not a waterproofing system. Where water enters through a junction, a flashing, a crack or a failed seal, a new coat hides the evidence for a season while the damage continues.
My house is monolithic-clad. Is it a leaky home?
Not necessarily — the national estimates describe a build period, not your house. But the estimated failure rates were 95% for monolithic and stucco against 2% for weatherboard, which is why a monolithic house deserves a moisture investigation before a repaint rather than after one.
Who should investigate it?
A building surveyor or suitably qualified building professional, with invasive testing where the readings justify it — not a painter, and not this site. Restricted building work must be carried out or supervised by a Licensed Building Practitioner.
The paint failed two years after the last repaint. What does that mean?
Usually one of two things: the surface was not prepared, or something is wetting it from behind. Those have very different costs, and the way to tell them apart is where the failure is. Even across an elevation suggests preparation; a defined patch in the same place both times suggests water.