Why you can't use interior paint outside
Interior paint is designed for stable, indoor conditions. It's formulated to be washable, low-odour, and to give a smooth finish on protected surfaces. It's not built to withstand rain, frost, UV light, or temperature swings.
If you use interior paint on an exterior surface, it will start to crack, peel, and flake within months. Exterior paint contains special resins and additives that make it flexible (so it expands and contracts with temperature changes) and resistant to moisture, mould, and UV degradation.
Types of interior paint
For walls and ceilings, the main choices are matt emulsion (flat finish, hides imperfections), silk emulsion (slight sheen, more washable), and soft sheen (between the two). Matt is the most popular choice for living rooms and bedrooms. Silk or soft sheen works well in kitchens and bathrooms where walls need occasional wiping.
For woodwork (skirting, doors, window frames), you'll want satinwood (mid-sheen, durable) or eggshell (low sheen, more traditional). Gloss paint is less common now but still used on some period properties. Water-based satinwood has largely replaced oil-based gloss for most interior woodwork.
Types of exterior paint
Exterior masonry paint is used on rendered, pebbledash, and brick surfaces. It comes in smooth and textured finishes and is designed to be breathable (allowing moisture to escape from the wall) while keeping rain out.
Exterior wood paint and preservatives protect doors, windows, fascias, and cladding from the weather. Products range from opaque paints to translucent stains that show the wood grain. For metal surfaces like railings and gates, you'll need a metal primer and exterior metal paint.
How long does exterior paint last?
Good quality exterior masonry paint typically lasts 5–10 years depending on the exposure and surface condition. South and west-facing walls take more weather and may need repainting sooner. Sheltered walls can last longer.
Exterior woodwork usually needs attention every 3–5 years, depending on the product used and how exposed it is. Regular maintenance — touching up any chips or cracks before they get worse — can extend the life of the paintwork significantly.
Choosing the right products
We use quality products from brands we trust — Dulux Weathershield for exterior masonry, Dulux Trade and Farrow & Ball for interior work, and specialist primers where needed. The right product for the right surface makes all the difference.
If you're unsure what your walls or woodwork need, we can advise. Every quote from New Decorating includes a recommendation on products and finishes suited to your specific property.
New Decorating
Professional painter and decorator based in Bath with over 25 years of experience. Fully insured. Free quotes across Bath and BANES.
