Interior vs Exterior Paint: What's the Difference?

Interior and exterior paints might look the same in the tin, but they are engineered very differently. Using interior paint outside — or exterior paint inside — causes real problems.

What makes exterior paint different?

Exterior paint must survive UV light, rain, humidity and temperature swings. It contains:

• Flexible resins that expand and contract with the surface
• UV-resistant pigments that resist fading
• Mildewcides and fungicides to resist mould in Sydney's humid climate
• Higher solids for a tougher, more protective film

What makes interior paint different?

Interior paint is formulated for looks and cleanability in a controlled environment. It typically has:

• Lower VOCs for better indoor air quality and less odour
• Washable, stain-resistant finishes for kitchens and high-traffic areas
• A smoother, more even sheen for walls and trims

Can you use one for the other?

No. Interior paint outside will chalk, crack and peel quickly because it cannot handle UV and moisture. Exterior paint inside can emit stronger fumes and often has a rougher finish — and its added fungicides are unnecessary indoors. Always use the right product for the surface.

Sheen guide

• Flat / matte — hides wall imperfections; best for low-traffic rooms.
• Low sheen / satin — durable and washable; the default for living areas.
• Gloss / semi-gloss — hard-wearing; ideal for trims, doors and wet areas.

A professional painter will spec the right paint for each surface. Compare local painters and request quotes:

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See also our guide to how often a house should be painted.