Problems start when the paint film becomes too impermeable, or when boards are replaced with sections that do not match the original profile or lap.
How boarding fails
Bottom edges and end grain go first, especially where a board runs into a junction, behind a downpipe, or close to a path that splashes back onto it.
Fixings are the second issue. Where boards have been face-nailed with steel and the nails have rusted, staining and splitting follow, and boards start to cup and let water behind.
Coatings and breathability
A thick, plastic-like coating traps moisture in the timber and blows off in sheets. Traditional breathable paint systems allow moisture out, weather gracefully and are much easier to maintain because they fail by thinning rather than by flaking.
Preparation is the majority of the work in any repaint: back to a sound edge, primed on all faces including cut ends, then built up in coats.
Replacing boards properly
Matching the profile and the lap is what makes a repair invisible. We machine boards to match rather than substituting a stock section with a slightly different face width.
New boards should be primed on all four faces before fixing, including the back, which is the single most commonly missed step and the reason many repairs fail early.
Common questions
How often should weatherboarding be repainted?
It depends on exposure and the coating used. A breathable system on a sheltered elevation goes many years; a south-west facing wall needs attention sooner.
Can I replace individual boards?
Yes, and that is the intended maintenance route. Matching the profile and priming all faces before fixing is what makes it last.
Should I use a modern masonry-type paint?
Not on timber boarding. Impermeable coatings trap moisture and cause the paint to blow and the boards to decay behind it.
Is composite boarding a sensible substitute?
On an unlisted modern building, possibly. On a historic weatherboarded cottage it looks wrong and is unlikely to be acceptable in a designated area.