Interior and exterior paint look the same in the tin. They are not. Each is made for a different set of conditions, and using one where the other belongs is one of the most common reasons a paint job fails early.

What exterior paint has to survive

An exterior wall in Melbourne's south east deals with full summer sun, winter rain, salt in the air the closer you get to the bay, and surfaces that expand and contract through big temperature swings. Exterior paint is built for that:

  • Flexible binders that move with the surface instead of cracking when a weatherboard or render wall heats up and cools down.
  • UV-resistant pigments that hold their colour under years of sun.
  • Mould and mildew inhibitors, because south-facing walls and shaded eaves stay damp long enough for growth to take hold.
  • Higher durability additives so the film resists chalking and breakdown.

What interior paint is made for

Inside, the enemies are different: scuffs, steam, kids, furniture and cleaning products. Interior paint is formulated for washability, low odour and low VOCs so rooms can be lived in while work happens. It doesn't need UV blockers or the same flexibility, so it doesn't have them.

Why you can't swap them

Exterior paint inside means stronger fumes and additives you don't need in a bedroom. Interior paint outside means a coating that chalks, fades and peels within a couple of seasons, because it was never made to handle sun and rain. The label matters more than the colour.

Finishes still apply on both sides

Within each type you still choose a sheen level. Outside, low sheen hides surface imperfections on render and weatherboards, while gloss suits trim, doors and gutters. Inside, flat hides ceiling flaws, low sheen handles family-room walls, and semi-gloss stands up to wet areas and trim. Our paint finishes guide walks through each one.

If you're not sure what your surfaces need, that's a normal part of the quoting conversation. Call 0420 596 677 and talk it through.