Preparing exterior walls for painting follows a clear order: wash, scrape back failed paint, sand, repair and fill, treat any mould or rot, then prime bare areas before the top coats go on. Skip a step and the new paint won't bond — good preparation is the single biggest reason an exterior repaint lasts 7–10 years instead of failing early.
The preparation steps in order
First the walls are washed to strip dirt, mould and chalk so the new paint has a clean surface to grip. Then any failed or flaking paint is scraped and removed, and the edges sanded and feathered so they don't telegraph through the finish. Cracks and gaps are filled and re-sealed, timber repairs are made, and moss or mould is treated to kill the spores.
Only once the surface is sound and clean do we prime — bare timber, repairs and any stained areas — before the top coats. Every step exists to give the paint something solid to bond to.
Weatherboard vs plaster and fibre-cement
Weatherboard has profiled boards and gaps that take longer to prepare, and tannin-rich timbers need a stain-blocking primer so they don't bleed through. Plaster and fibre-cement are flatter and quicker to coat, but need crack repair with the right fillers and a masonry-appropriate primer, plus a check for hairline cracks and render damage that let water in.
What homeowners can do to help
You can speed the job and keep costs down by trimming back plants and shrubs touching the walls, moving pots and furniture clear, and flagging any known leaks, rot or problem areas before we start. Clear access makes the work faster and safer. It's worth knowing that preparation is usually the bulk of the labour on an exterior job — and that's exactly where the durability comes from. For a homeowner's overview of the whole process, see our guide on preparing your house for exterior painting.
Frequently asked questions
Can I just paint over old exterior paint?
Only where the existing paint is sound and clean. Any failed, flaking or peeling paint must be removed first, or the new coat will lift with it.
Do I need to prime bare timber?
Yes — bare and weathered timber must be primed, or the top coat won't bond and will peel. Tannin-rich timbers also need a stain-blocking primer.
How long does exterior prep take?
Often longer than the painting itself. Washing, scraping, sanding, repairing and priming is where a lasting finish is made.
