Painting a weatherboard home in Melbourne: what makes it different

A rendered wall is one surface. A weatherboard house is a few hundred separate pieces of timber, each with a face, two edges, exposed end grain at the joints, and a nail through it. Every one of those pieces swells and shrinks a little as Melbourne moves between a damp July and a dry February.

That movement is the whole story. It dictates the preparation, the primer, the type of paint and, most importantly, which gaps you fill and which you deliberately leave open. Get the approach right and a weatherboard repaint comfortably runs seven to ten years. Get it wrong, and the joints will tell you inside two.

Moisture comes before everything else

Timber has to be dry before it is coated. Industry guidance puts the moisture content for priming in the range of fourteen to eighteen per cent, measured with a calibrated meter rather than judged by feel. Paint applied over damp timber traps the moisture underneath, and the result is blistering and peeling that looks like paint failure but is actually a water problem wearing a disguise.

Which means the real first question is where the damp is coming from. Common culprits on older Melbourne homes are garden beds built up against the boards, soil or paving sitting too close to the bottom board, a downpipe discharging at the wall, a blocked gutter overflowing behind the fascia, and sprinklers hitting the cladding every morning. Fix those first. Painting over them just buys a few months.

Carpentry happens before painting

On any weatherboard house past about forty years old, expect some board work. Split boards, soft or decayed sections around windowsills and at ground level, boards that have cupped away from the stud, and loose or popped nails. None of that is paintable in the state it is in.

Replacing a board properly includes priming the back and the cut ends before it goes up, because end grain absorbs water many times faster than the face does. A repair that skips back priming will show as a stain or a swelling within a couple of seasons. You can see the difference carried through a full exterior across our residential exterior portfolio.

Nail heads and rust bleed

Steel nails in older cladding rust, and the rust bleeds up through the topcoat as brown tears running down the board. Sanding the stain off does nothing, because the source is still sitting under the surface.

The fix is to punch the head below the surface, treat or spot-prime the exposed metal with a suitable metal primer, fill, then prime again before the system goes on. It is slow, it is invisible in the finished job, and it is one of the clearest tells between a thorough quote and a cheap one.

The gaps you seal, and the ones you must not

This is the single most misunderstood part of weatherboard work, and the mistake is almost always made with good intentions.

• Seal: junctions around window and door frames, where trim meets cladding, and at corner mouldings, using a flexible paintable exterior sealant
• Fill: nail holes, small splits and surface defects, with a flexible exterior-grade filler rather than an interior patching compound
• Leave open: the horizontal lap where one board overlaps the next

Those laps are not a defect. They are the drainage and ventilation path that lets any moisture getting behind the cladding escape again. Caulk them shut, and you seal water in behind the boards, which is how a well-intentioned weekend of silicone turns into rot. Rigid fillers cause a related problem, cracking out the first time the timber moves and leaving an open seam exactly where you tried to close one.

Primer is not optional on timber

Bare timber drinks paint unevenly, so any exposed, scraped back or newly repaired section needs priming before the finish coats. Knots and tannin-rich timbers need more than a general primer, because tannin bleeds through as brown discolouration months later, usually on the lightest colour you chose. A stain-blocking or oil-based primer on those areas stops it.

Previously painted boards that are still sound are a simpler proposition, needing a clean, a light sand and an appropriate undercoat rather than a full strip. A proper inspection is what tells you which category each elevation falls into, and the two usually coexist on the same house.

Flexible beats hard on moving timber

A hard, brittle film looks beautiful on day one and cracks at the joints as the boards move. A quality one hundred per cent acrylic exterior system stays flexible enough to move with the timber while still shedding water and resisting Melbourne’s UV load. That flexibility is the reason it outperforms cheaper blends on cladding specifically, whatever the tin promises about coverage.

Sheen is worth a thought too. A satin or low sheen finish on weatherboard cleans more easily and copes better with the chalking that strong sun causes, while very flat finishes hold dirt in a way that shows on a south-facing wall in a damp winter. If you are weighing paint against a clear finish on feature timber, the trade-offs are different again, which our post on timber staining goes into.

Two things specific to older Melbourne weatherboard

First, colour and heat. Very dark colours on timber cladding absorb significantly more heat, which increases the movement the coating has to cope with and accelerates fading on north and west elevations. Dark weatherboard is achievable and popular, but it asks more of the system and of the preparation underneath it.

Second, and more important, if the house dates from before about 1970, the existing paint may contain lead, and weatherboard is the worst case because scraping and sanding are unavoidable on timber. That work needs containment and controlled waste handling rather than a sander and a bin. Settle that question before anyone starts, not once the dust is already in the garden. For the full scope of what a weatherboard exterior involves, our exterior house painting page sets out how we approach it, and the Frankston project shows it on exactly this kind of home.

Frequently asked questions

Our boards look fine. Can we just paint straight over them?

Sometimes, if the existing coating is genuinely sound and well adhered. The test is not how it looks from the footpath. Check the bottom board, the end grain at the joints, the sills and the shaded southern elevation, because those fail first, and a house can look perfect from the street while three of those four are gone.

Can weatherboards be pressure washed before painting?

Low-pressure washing is normal and useful. High pressure is a problem on timber, because it drives water up under the laps and into the end grain, raises the grain, and on older homes it can blast lead-contaminated paint across the garden. If boards are washed, they then need time to dry back before any coating goes on.

Should the gaps between the boards be caulked?

No. The horizontal lap between boards needs to stay open so moisture behind the cladding can drain and the wall can breathe. Sealing them is one of the most common well-meant mistakes on a weatherboard house. Caulk belongs around frames, trim and corners, not between the boards themselves.

Is dark grey or black a bad idea on weatherboard?

Not a bad idea, just a more demanding one. Darker colours run hotter, which increases timber movement and fades faster on sun-exposed elevations. If you want a dark exterior, spend the extra on preparation and on the quality of the system rather than economising there and hoping the colour carries it.

How long should a weatherboard repaint last in Melbourne?

With sound timber, proper preparation and a quality exterior system, seven to ten years is a reasonable expectation, with north and west elevations usually needing attention before the rest. Shorter than that generally points to a moisture source that was never resolved rather than to the paint itself.

Thinking about repainting the boards? Get them looked at board by board

A weatherboard quote written from the footpath is a guess. The information that decides the price and the lifespan sits at the bottom board, behind the downpipe, at the window sills and along the shaded wall nobody photographs.

Meggyco Painting Pty Ltd inspects weatherboard elevation by elevation, identifies the repairs and the moisture sources before quoting a coating system, and carries $10 million in public liability cover. Call (045) 071 2009 or get in touch at meggycopainting.com.au, and we will tell you what your timber actually needs, including the parts you would rather not hear.