Choosing exterior colours that survive Perth light
2 August 2026 · 4 min read
Why the grey you chose indoors reads blue on the west wall, how much heat a dark exterior really adds, and the sampling method that prevents expensive mistakes.
Perth light is harsh, warm and very bright. It does things to colour that catalogue photography and showroom lighting do not prepare you for.
Why your grey went blue
Most fashionable greys are not neutral. They carry an undertone — blue, green, violet or brown — that is invisible under the balanced light of a paint shop and obvious on a west-facing wall at four in the afternoon.
Perth's afternoon light is strongly warm. Warm light exaggerates cool undertones by contrast. A grey with a blue undertone that looked sophisticated on a card reads distinctly lilac or icy on a sunlit render wall.
The fix is not to avoid grey. It is to test the specific grey on the specific wall.
How to read an undertone before you commit
Put the sample card next to a piece of plain white printer paper. Against true white, the undertone becomes obvious — the card that looked neutral will read visibly blue, green or pink.
Then do it again outdoors, on the elevation you are painting, at the time of day you most often see the house.
Sampling properly
Almost everyone samples wrong. The two mistakes are painting too small a patch, and painting it in one place.
The sampling method that works
Paint a minimum of A3 size, in two coats, on at least three separate elevations — one that gets morning sun, one that gets afternoon sun, and one in shade. Look at all three at three different times of day. A colour that works in all nine conditions will work.
Better still, paint the sample on a piece of primed board rather than the wall, so you can move it around, hold it against the roof, and stand it next to the fence and the driveway.
Heat
This one is measurable and it matters in Perth.
Surface temperature on a north-facing wall, 38 degree day
Those are surface temperatures, not indoor temperatures, but they drive what the wall radiates into the building. A dark exterior on a west wall with no eave will make the room behind it noticeably hotter.
Dark exteriors are beautiful and we paint plenty of them. Two things make them work:
- **Heat-reflective formulations.** Several manufacturers make dark colours using pigments that reflect infrared while still absorbing visible light. They can drop surface temperature substantially for the same apparent colour.
- **Substrate tolerance.** Not every substrate is happy at 78 degrees. Some cladding and some render systems have a maximum recommended light reflectance value, and going darker than that can void the substrate warranty. Check before you choose, not after.
Check your LRV limits before falling in love with a colour
If your house has a proprietary render system or lightweight cladding, the manufacturer may specify a minimum light reflectance value. Painting below it can void their warranty. This catches people out on double-storey rendered homes in particular.
Working with what you cannot change
The roof is the biggest fixed colour on the house and almost nobody accounts for it.
| Roof | Works well with | Fights with |
|---|---|---|
| Terracotta tile | Warm creams, sandstones, olive greens | Cool greys, blue-based whites |
| Charcoal Colorbond | Almost anything, including cool greys | Very warm yellows |
| Red or brown brick | Creams, warm whites, deep greens | Pink-based neutrals |
| Grey concrete tile | Cool and warm neutrals both | High-chroma colours |
Brick, driveway, fence and neighbouring houses are all fixed too. Take the sample board outside and hold it against each of them.
A workable three-colour formula
Most exteriors that look considered use three colours and no more:
- **The field** — the main wall colour, and the one to keep quiet
- **The trim** — fascia, barge, window frames. Usually much lighter or much darker than the field, rarely close to it
- **The accent** — the front door, and only the front door
The failure mode is a trim colour that is *slightly* different from the field. It reads as a mistake rather than a decision. Commit to the contrast or match exactly.
The one rule
Never choose a final colour from a screen, a catalogue, or a 50mm chip. Screens differ from each other, printed cards differ from paint, and a small chip surrounded by white always reads lighter than a whole wall.
We include colour consultation with every repaint, and we would much rather spend an hour on this than repaint a house twice.