Identify what you have first
“Stone veneer” covers several materials, and the right cleaning method depends on which one you have:
- Manufactured (cultured) stone, usually cement-based and colored to look like natural stone
- Natural thin stone veneer, real stone cut thin and attached with mortar
- Vinyl or polyurethane panels made to look like stone
If you do not know, check the paperwork from the installer or manufacturer, and contact the manufacturer for cleaning recommendations. Their guidance may also affect your warranty. In all cases, test your method on a small hidden area first.
What you need
- Soft-bristle brush (nylon, not wire)
- Garden hose
- Bucket
- Mild dish soap or a gentle cleaner suited to your material
- Sponge or soft cloth
- Eye protection and gloves
- Tarps or plastic to protect plants and nearby surfaces
Basic cleaning: step by step
- Brush off loose debris. Use a dry soft brush or vacuum brush attachment on dust and cobwebs.
- Protect the area. Cover plants and sensitive surfaces, and wet nearby plants.
- Wet the stone lightly with a hose. This keeps soap from soaking deeply into the surface.
- Wash gently. Mix a small amount of mild dish soap into warm water. Scrub in sections with a soft brush or sponge.
- Rinse thoroughly with clean water, working from top to bottom so soap does not dry on the surface.
- Let it dry, then check for remaining stains.
Use low water pressure. A pressure washer can strip color, erode mortar, roughen the surface, and push water behind the veneer. Most manufacturers advise against it.
Exterior stains: moss, algae, mildew
Green or black growth is common on shaded exterior walls. First try the soap-and-water method with a little more scrubbing time. If growth persists, use a cleaner that the veneer maker approves for your product. Some pros use diluted bleach-based mixes on cement-based veneer, but bleach can lighten color or harm plants, and it is not suitable for every type. Check with the manufacturer.
Safety: Never mix bleach with ammonia, vinegar, or acid-based cleaners, since this can create toxic gases. Keep children and pets away while you work and until surfaces and nearby soil are rinsed. For more on low-pressure exterior cleaning and chemical safety, read how to soft wash a house.
Efflorescence and mineral deposits
Efflorescence is a white, powdery deposit left when moisture carries salts to the surface. Start by dry-brushing it off. Persistent deposits can signal a moisture problem behind the veneer, such as a leak, bad flashing, or poor drainage, and cleaning alone will not stop it from coming back. Acid-based cleaners are sometimes used on masonry, but they can etch or discolor some stones and cement products. Only use one if the manufacturer approves it, and never mix it with bleach.
Fireplace soot
Indoors, soot often comes from smoke that escapes the fireplace. Dry-brush or vacuum gently, then wipe with a lightly dampened sponge and mild soap, taking care not to saturate the stone. Burn well-seasoned wood, have the chimney inspected by a professional, and sweep the hearth regularly to reduce buildup. Do not use wire brushes, which can scratch the surface. For a real stone surround, see how to clean a natural stone fireplace.
What to avoid
- High-pressure washing
- Wire brushes and abrasive pads
- Strong acids and unapproved chemical strippers
- Bleach without manufacturer approval
- Letting soap dry on the surface
- Mixing cleaning products
Can you use dish soap?
Mild dish soap diluted in water is a common starting point for cleaning stone veneer and is generally considered gentle. Use a small amount and rinse thoroughly, because leftover soap can leave a film or attract dirt. Check that your stone type does not have special care instructions.
Preventing buildup
- Trim plants back from the wall to improve airflow
- Make sure gutters and sprinklers do not spray the veneer
- Fix leaks and drainage issues
- Brush off dust and cobwebs periodically
- Clean lightly once or twice a year
When to call a professional
Call a pro for tall walls that need a ladder, for widespread staining, or for suspected moisture problems. Veneer that is cracking, loose, or hollow-sounding needs repair instead of cleaning. If your home has other exterior surfaces to maintain, like aluminum railings, choose cleaning products suited to each material and avoid cross-contamination of runoff.