A successful exterior house painting job comes down to three things: thorough prep, the right products for the surface, and painting in the right weather. Wash and repair the surface, prime bare and stained areas, then apply two coats of quality exterior paint on a mild, dry day. Get those fundamentals right and the finish will last for years.
Skipping prep is the number one reason exterior paint fails early. This guide walks through cleaning, repairs, priming, product choice and timing so your effort pays off across a hot, sun-baked Australian summer and a wet winter alike.
Why does exterior prep matter so much?
Outside surfaces cop sun, rain, salt air and grime that indoor walls never see. Paint can only bond to a clean, sound, dry surface, so any dirt, chalk, mould or flaking coating left behind becomes the weak link.
Good preparation isn't glamorous, but it's where a ten-year finish is won or lost. Budget most of your project time for prep, not the painting itself.
Step 1: Wash and clean the surface
Start by removing dirt, cobwebs, mould and chalky residue. A pressure washer makes short work of large walls, or use a stiff brush and sugar soap for smaller areas and delicate surfaces.
Treat any mould with an appropriate wash and let the whole house dry out completely. Painting over a damp or dirty wall traps the problem underneath and guarantees peeling.
Step 2: Scrape, sand and repair
Scrape away loose and flaking paint, then sand back hard edges so they don't telegraph through the new coat. Fill cracks and holes with a suitable exterior filler and knock back proud spots once dry.
Gather your prep gear from a good selection of building consumables before you begin. For small surface nicks on trim, thresholds and adjacent hard flooring, a fast-drying product like the Roberts quick-repair floor putty fills minor gaps neatly so you're not waiting around.
Dealing with rust on metal fixtures
Downpipes, brackets, railings and steel window frames often carry rust that will bleed through fresh paint. Treat it first with a converter such as the Dulux Autoshield rust converter spray, which reacts with rust to form a stable, paintable base before your topcoat goes on.
Step 3: Spot-prime bare and stained areas
You rarely need to prime an entire sound wall, but always prime bare timber, filled repairs, exposed render and any stained patches. Primer seals the surface and stops old marks and tannins bleeding into your new colour.
For stubborn stains and timber knots, a stain-blocking sealer like the Zinsser Covers Up stain-sealing aerosol locks marks in so they don't ghost through. Let all primer cure fully before topcoating.
Step 4: Choose the right exterior products
Match the paint to the substrate. The wrong product on the wrong surface is a fast track to failure, so use this quick guide.
| Surface | Recommended approach | Notes |
|---|---|---|
| Rendered / masonry | Exterior acrylic membrane or low-sheen | Flexible coatings bridge fine hairline cracks |
| Weatherboard timber | Prime bare wood, then exterior acrylic | Low-sheen or satin hides minor surface flaws |
| Fibre cement sheet | Exterior acrylic over sound existing paint | Seal cut edges before painting |
| Metal (gutters, trim) | Rust converter, then metal-suitable topcoat | Treat all rust first for adhesion |
| Trim and doors | Exterior enamel or gloss acrylic | Harder wearing on high-touch edges |
Stock the rollers, brushes, trays and masking tape you'll need from a painting consumables range so you're not stopping mid-wall. For fiddly detail such as fence caps, bracket ends and small metal fittings, a quick-drying aerosol like the Dulux 340g flat black spray paint is self-priming and touch-dry in around ten minutes.
Step 5: Time it right with the weather
Weather makes or breaks the finish. Aim for mild, dry, still conditions and check the forecast for the days either side, not just the morning you start.
- Avoid extreme heat. Paint applied in scorching sun can skin over too fast and blister. Follow the shade around the house.
- Avoid painting before rain. Fresh paint needs dry time to cure, so check no showers are due.
- Watch the dew. Stop in time for coats to dry before evening moisture settles.
- Mind the wind. Gusty days blow dust and grit onto wet paint.
Spring and autumn often deliver the most reliable painting windows in much of Australia, avoiding both peak summer heat and winter damp.
Step 6: Apply and finish well
Cut in edges and corners first, then roll the main areas while the cut-in is still wet to avoid lap marks. Two coats give far better coverage, colour depth and durability than one stretched coat.
Work in manageable sections and keep a wet edge as you go. Allow the recommended drying time between coats rather than rushing the second pass.
Common mistakes to avoid
- Under-preparing. Most early failures trace straight back to skipped cleaning or repairs.
- Painting in the wrong weather. Heat, rain and dew all sabotage curing.
- Ignoring rust and mould. Both bleed or grow straight through fresh paint.
- One thick coat. It sags, cures unevenly and wears out faster than two thin ones.
- Cheap brushes and rollers. They shed and leave marks that show for years.
Cleaning up your gear
Clean water-based paint from brushes and rollers with warm water straight after use. For enamel and stubborn residue, a solvent such as Diggers methylated spirits helps shift paint and clean tools and hard surfaces. Work in a ventilated spot and store leftover paint sealed for future touch-ups.
When to call a pro
Single-storey homes are achievable for a determined DIYer over a few weekends. Bring in a licensed painter for double-storey work needing scaffolding, homes with suspected lead paint from older coatings, or extensive substrate repairs, where safety and the right access equipment matter more than the cost saving.
Frequently asked questions
How long does exterior house paint take to dry between coats?
Most water-based exterior acrylics are touch-dry within an hour or two and recoatable after two to four hours, depending on the product and weather. Always check the tin, as heat, humidity and cool evenings all change the timing. Give each coat its full recommended time so the finish cures hard and adheres properly.
What is the best temperature for painting outside in Australia?
Mild, dry, still days give the best results, roughly the shoulder-season conditions of spring and autumn. Very hot sun makes paint skin over too fast and blister, while cold, damp air slows curing. Follow the shade around the house through the day and check the label for the product's minimum application temperature.
Do I need to prime before painting the exterior of my house?
You don't have to prime a sound, previously painted wall, but you should spot-prime bare timber, filled repairs, exposed render and stained areas. Primer seals the surface and stops old stains and tannins bleeding through. Treat any rust with a converter first, as rust will ruin adhesion and show through the topcoat otherwise.
How many coats of paint does an exterior wall need?
Two coats is the standard for exterior walls and gives far better colour, coverage and durability than one stretched coat. Over bare or patchy surfaces you may also want a primer coat underneath. One thick coat is a false economy, as it sags, cures unevenly and wears out much faster than two thin, even coats.
