What paint should I use on weatherboards near the coast?

Buy a system, not a tin

Paint companies do not test a topcoat on its own. They test a primer and topcoats together on a named surface, and everything they promise is tied to that combination being used the way the label describes. Dulux's Weathershield Promise is a good example: it covers the paint against peeling, flaking and blistering for as long as you live in the home, on the condition that the product was applied per instructions on a suitable substrate.

So the question is not really which paint is good. It is which primer plus which topcoat, at how many coats, on the timber you actually have. Get that combination right and the brand argument mostly stops mattering.

Which primer goes under the topcoat?

Bare, sanded or newly replaced boards need priming before any colour goes near them. Dulux 1Step Prep is the general-purpose water-based option: 14 square metres a litre, touch dry in 20 minutes, recoat in 2 hours, one coat on most surfaces, and stain blocking for tannin and flash rust. It is listed for exterior as well as interior use, and for timber among many other surfaces.

The exception is worth knowing before you buy. Dulux says very dark, tannin-rich timbers are better sealed with its oil-based 1Step primer, because the tannin will otherwise find its way up through a water-based coat and stain the finish brown. Cedar and some hardwoods are the usual culprits.

Where the existing paint is sound, you are not priming the whole house, only the patches you have taken back and anything bare.

What the topcoat data sheet actually promises

Dulux Weathershield Low Sheen lists a spread rate of up to 16 square metres a litre, touch dry in 20 minutes and a recoat time of 2 hours measured at 25 degrees and 50 per cent humidity. It sets a minimum of 5 degrees during application and drying, and asks for a 10 to 12 millimetre roller. Dulux describes the film as carrying MaxiFlex technology to expand and contract with the surface, with sun protection and resistance to colour fading.

Haymes Solashield, from the Australian-owned Haymes, reads much the same on the numbers: coverage around 16 square metres a litre depending on how porous and how profiled the surface is, touch dry around 20 minutes, recoat around 2 hours, with those times quoted at 25 degrees and 50 per cent relative humidity.

Two established manufacturers landing in the same place tells you something useful. At this end of the market the differences are in colour ranges, availability and what your painter is set up to buy, not in a secret formula that beats the salt.

What salt air changes about the choice

The paint on the boards is only part of it. Salt attacks metal long before it does anything visible to an acrylic film, so on a house near the water the gutters, downpipes, fascia brackets, garage door, handrails and any galvanised fixings decide how the place looks in five years.

Dulux writes the rule into the Weathershield sheet: for galvanised surfaces within one kilometre of the sea, prime with one coat of Dulux Precision All Metal Primer before the topcoats. If you live in Mount Martha, Safety Beach, Seaford or anywhere along the bay, that sentence is describing your house.

There is a second, duller job the tin cannot do for you: getting the salt off the surface before you paint. Salt that is still on the wall sits between the old paint and the new, which is exactly where you do not want a layer of anything.

• Wash the whole wall down, rinse it, and let it dry before any coating goes on.
• Prime galvanised metal within a kilometre of the water before topcoating it.
• Check fixings and flashings while the ladder is up: rust bleeds through new paint within a season.
• Do not leave bare board ends and cut edges unsealed, because that is where water gets in.

Does the colour make a difference?

Dark colours absorb more heat, which means more movement in the boards behind them and a harder life for the film on top. Dulux answers that with flexibility, and claims fade resistance and sun protection, but a charcoal wall facing north-west on an exposed block is still the hardest thing you can ask of any exterior paint.

None of that makes dark colours wrong. It does mean thinking about which walls take the full afternoon sun, and being realistic that a deep colour on those walls is a shorter cycle than a mid-tone on a sheltered side.

Low sheen or gloss on the boards?

Low sheen is the usual pick for weatherboards because a shinier film reflects light along the wall and shows up every ripple, sanding mark and nail head. Gloss earns its place on the front door, the window frames and anything you want to look sharp and wipe clean. Our guide to which sheen suits which surface goes through the rest of the house.

Can you do it yourself, and when is it worth getting a painter in?

A single storey weatherboard house with ground-level access, sound paint and a couple of free weekends is a genuine do-it-yourself job. Bunnings gives a workable outline in its weatherboard guide, including the temperature window of above 10 and below 35 degrees and an 80-grit sand on the boards. Work out how much paint the walls will take before the first trip to the shop.

It stops being a home job at a few clear points.

• Double storey walls, gable ends and anything above a single-storey ladder, especially on the sloping blocks around Mount Eliza and Frankston South.
• Paint from before 1970 that needs sanding, because of the lead risk. We do not take on lead paint removal, and we will say so at the quote rather than sand it.
• Rotten or split boards, which are a carpentry job before they are a painting one.
• Anything you want sprayed, which needs masking and gear that is not worth buying for one house.
• Timber that has gone grey and soft, where the sanding is the whole job. Our guide on stripping old weatherboards covers how far back that has to go.

If you would rather not

We quote exterior repaints across Frankston and the Peninsula in writing, with the product and the number of coats named for each surface, including the metal. Ask us what is going on the gutters. If a painter cannot answer that on a coastal house, keep looking.

Quick questions

Sources

What this guide relies on. Product advice changes, so check the maker's current instructions for the exact paint you're using.

1. Weathershield Low Sheen: spread rate, drying, coastal metal priming — Dulux
2. 1Step Prep water based primer, sealer and undercoat — Dulux
3. Ultra Premium Exterior Solashield Low Sheen — Haymes Paint
4. How to paint weatherboards — Bunnings Warehouse