All in the preparation
Painting over a poorly prepared surface is a waste of time and money as it won’t last very long. If the old paint is in good condition, all it needs is a wash to remove any dirt. Flaking paint should be scraped off until it’s sound then sanded to blend the remaining paint with the bare surface. Glossy paint and materials should be lightly sanded to roughen the surface and allow the new paint to bond.
All bare timber will need to be undercoated. An oil-based undercoat is best as it helps to seal the timber. If you’re using a water-based enamel as your final coat, go over the oil-based with an acrylic undercoat to provide a better bond. Water-based exterior paints generally don’t need undercoats as they are self-priming. Exceptions to this are when you are using bright or dark colours. There are also a range of specialist undercoats for binding loose or chalky surfaces, for quickly covering dark colours and for sealing in stains.
Which paint where?
Exterior walls, eaves and fascia (the part the gutter sits on) are best painted in exterior acrylics which are water-based. They dry quickly and are designed to handle the tough Aussie conditions. Use low sheen on walls and eaves as they hide minor imperfections and semi gloss on the fascia. Timber windows and doors are best coated in enamels, which are more hard-wearing than acrylics. A water-based enamel is a good option as it dries quickly and won’t fade over time. Choose a gloss or semi gloss finish.
Metal surfaces need special attention. If it’s rusted, scrape off any loose rust and treat with a rust converter. This stops the rusting process and prepares the surface for fresh paint. Use metal primer on all bare metal. A spray paint is the best way to tackle intricate surfaces with lots of nooks and crannies. Finish off with a paint specifically designed to go onto metal in the finish of your choice.