Yes. Wash your walls before you paint. Dust, grease, and grime keep paint from bonding, and that leads to peeling, flaking, and patchy color.
This guide shows how to clean walls before painting, and when soap and water is not enough. If you would rather have it done right the first time, see how HBP’s interior house painters prep every wall before a single coat goes on.
Do You Need to Wash Walls Before Painting?
Most walls need at least a dusting. Walls in kitchens, bathrooms, hallways, and entryways usually need a full wash. New drywall needs dusting only.
Skipping this step shows up later. Paint can peel, and hand marks or grease spots can show through the new coat.
What You Need to Clean Walls Before Painting
- A soft brush, or a vacuum with a brush attachment
- Two buckets, one for soapy water and one for rinse water
- A sponge or a soft microfiber cloth
- Mild dish soap
- A drop cloth for the floor and clean towels for drying
- Rubber gloves
What Is the Best Way to Clean Walls Before Painting?
Mild soap and warm water clean most walls. Dust first, then wash. Dust turns to mud when it gets wet, and mud smears across the wall instead of coming off.
How to Wash Walls Before Painting
Follow these steps, one wall at a time:
- Lay a drop cloth along the baseboard and move furniture away from the wall.
- Dust the wall from the top down with a soft brush or a vacuum brush attachment. Get the corners and cobwebs too.
- Add a small squirt of mild dish soap to a bucket of warm water and stir.
- Wash one small section at a time, from the bottom up. Wring the sponge out well. It should be damp, not dripping.
- Rinse the section with clean water and a fresh cloth. Soap left on the wall can block paint the same way dirt does.
- Dry the wall with a clean towel, then let it air dry a few hours in a well-ventilated room. Give humid rooms longer.
Match the Cleaning to the Paint Finish
The finish on the old paint decides how hard you can scrub. Test a small spot in a hidden corner first.
- Flat or matte paint: marks easily and can lose color when scrubbed. Use very little water and a light touch.
- Eggshell or satin paint: handles a gentle wash with a damp sponge.
- Semi-gloss or gloss paint: takes the most scrubbing. This is the easiest finish to clean.
When Soap and Water Is Not Enough
Some walls need more than soap. Kitchens build up a thin layer of cooking grease. Bathrooms build up soap scum and moisture film. Either one can make new paint peel or fail to bond.
- Kitchens and greasy walls: use a degreasing cleaner, or TSP (trisodium phosphate) mixed the way the label says. Wear gloves, open a window, and rinse well.
- Bathrooms and humid rooms: check for mold or mildew before you paint. A mildew cleaner works, or a mix of 1 part bleach to 3 parts water. Never mix bleach with ammonia. Painting over live mold only traps it under the new coat.
- Smoke or nicotine stains: a stronger degreaser plus a stain-blocking primer. The stain can bleed through fresh paint even after washing.
Can You Paint Over Unwashed Walls?
You can, but it is a bad idea. Paint bonds best to a clean, smooth surface. Over dirt or grease it can flake, crumble, or dry with an uneven finish.
Cleaning is the first step, not the only one. Here is what materials you need to prepare walls for painting once the wall is dry.
Which Rooms Need Extra Attention?
Not every wall gets equally dirty. In Greater St. Louis homes, whether in the city, O’Fallon, or St. Charles, a few areas need more than a quick dusting. Humid St. Louis summers also mean walls dry slower.
- Hallways and entryways: hand marks and scuffs build up at light-switch height and along stair rails.
- Kitchens: cooking grease settles on walls near the stove and drifts several feet beyond it.
- Bathrooms: humidity and soap residue collect near the shower and sink.
- Around light switches and door frames: the most touched spots in any room, and the first to show through a fresh coat if skipped.
Wash the Walls Yourself or Hire Painters?
HBP Painting Contractors prices interior house painting at $3.00 to $12.00 per square foot of room, with labor and materials included. Wall prep is one of the things that moves the number, along with the complexity of the work, the number of coats, the surfaces, and the finish you choose. Treat it as a starting point, not a quote.
Washing and repainting works best on painted drywall in good shape. If the paint is peeling in sheets, or the wall is wallpaper or unsealed plaster, washing is not enough. That is when to call painters. If your home was built before 1978, test old paint for lead before you scrub hard or sand.
If your walls have heavy grease, smoke stains, or mildew, ask for a free on-site look before you start.
Frequently Asked Questions
HBP Painting Contractors has been family-owned and painting St. Louis homes since 1983 (43 years), with BBB-accredited, PCA-member crews, our own employees, not subcontractors. We prep every wall before painting. Get a free, no-obligation estimate, or call 636-544-1254.
