Painted timber weatherboards – bubbling or blistering of paint
Causes
Loss of adhesion due to excess moisture in substrate
Poor initial substrate preparation
Oil-based (alkyd) paint applied over water-based (latex) paint
Surface was damp or dirty when painted previously
Dark colours increasing surface temperatures
Water-based paint coat exposed to moisture before paint has fully dried
Listed under: Exterior, finishes, timber and wood-based, paint, timber, cladding, walls, moisture, wall cladding, painted timber weatherboards, lead-based paint
Cause
Loss of adhesion due to excess moisture in substrate
Repair
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follow the preparation and repainting guidance for the first repair. After scraping and removing loose paint, pay particular attention to any joints, gaps, cracks or splits in the weatherboards. Ensure they are primed and/or filled with flexible filler as appropriate before painting – follow the product manufacturer’s guidance.
Cause
Poor initial substrate preparation
Repair
- follow the preparation and repainting guidance for the first repair. Be careful with preparation, ensuring the substrate is completely clean and dry before painting begins.
Cause
Oil-based (alkyd) paint applied over water-based (latex) paint
Repair
-
oil-based paint should generally not be applied over water-based paint. To determine whether an existing paint finish is water-based or solvent-based:
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soak a cotton ball in rubbing alcohol (isopropyl or ethyl alcohol), an acetone-based nail polish remover or lacquer thinner]
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rub it over a small, inconspicuous section of wall
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if paint comes off, it is water-based; if unaffected, it is a solvent-based paint
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follow the preparation and repainting guidance for the first repair. Apply at least two coats of good quality high-gloss or semi-gloss water-based paint.
Cause
Surface was damp or dirty when painted previously
Repair
- follow the preparation and repainting guidance for the first repair. Be careful with preparation, ensuring the substrate is completely clean and dry before painting begins.
Cause
Dark colours increasing surface temperatures
Repair
- follow the preparation and repainting guidance for the first repair. Scrape/sand off all the old dark-coloured paint. Repaint with a good quality high-gloss or semi-gloss acrylic paint in a light colour. Darker colours attract heat, which can cause greater expansion/contraction of the timber, and thus a reduced lifespan for the paintwork.
Cause
Timber swelling/shrinkage caused by moisture absorption into timber end grain if joints were not adequately primed before installation
Repair
- follow the preparation and repainting guidance for the first repair. After scraping and removing loose paint, pay particular attention to any joints, gaps, cracks or splits in the weatherboards. Ensure they are primed and/or filled with flexible filler as appropriate before painting – follow the product manufacturer’s guidance.
Cause
Water-based paint coat exposed to moisture before paint has fully dried
Repair
- follow the preparation and repainting guidance for the first repair.