How to prep walls for painting?
Wash anything greasy or smoky with a degreasing cleaner, rinse it, and let it dry fully. Dust everything else with a vacuum and a damp cloth. Paint bonds to the surface it touches, so a film of cooking grease or nicotine means it bonds to that film rather than to the wall.
What actually needs washing
Kitchens and the wall above a cooker need real degreasing, not a wipe. So does anywhere a smoker has lived, and any bathroom with visible mildew. Everywhere else, dust and cobwebs are the actual problem and a vacuum with a brush head plus a damp cloth handles them.
Rinse after any detergent. Cleaner residue left on the wall is itself a bond breaker, which is a genuinely common cause of paint peeling off a wall that was, in fairness, washed.
Let the wall dry completely before priming or painting. Water trapped under a fresh coat causes blistering days later, when it finally works its way out.
On a home built before 1978, be careful about wet-cleaning surfaces with chipping or flaking paint — you can spread lead-bearing dust rather than remove it. Read the lead guidance before disturbing any old, failing paint.
How we sourced this
This answer is composed from our knowledge base, which holds only what a regulator, a standards body or a manufacturer supports. The sources behind it are listed below with the date we accessed each one. If a claim on this page has no source under it, that is a bug — tell us and we will fix it.
Where a figure is product-specific — coverage, dry time, recoat time, temperature limits — we point you at the manufacturer's technical data sheet rather than printing a general number as though it were a specification. That distinction is the most common error in this trade, and it is the one that costs people a repaint.
Common mistakes
- Skipping the rinse. Detergent residue is itself a bond breaker and causes peeling on a wall that was washed.
- Painting before the wall is fully dry, which blisters days later.
- Wiping greasy kitchen walls rather than degreasing them properly.
- Wet-cleaning chipping pre-1978 paint, which spreads lead dust rather than removing it.
Related questions
Sources
- Sherwin-Williams. Product technical data sheets (accessed 2026-08-17).
- US Environmental Protection Agency. Renovation, Repair and Painting Program (accessed 2026-08-17).
Also asked as
- How to prep walls for paint?
- How to prep for painting walls?