Prep first
Before you start
- Brush off the loose salt before any liquid touches it.
- Blot from the edges inward, never rub.
- Rinse with lukewarm water and blot dry.
- Test any wash on a hidden spot first.
Salt residue on siding can dry into yellow or streaky marks, especially after winter de-icing or when salt water from a pool splashes onto the wall. Brush off the dry salt first, then blot and rinse with lukewarm water before any soap goes on. Your siding material decides how hard you can scrub, so check it before you move past a gentle wash.
A yellow salt water pool stain on siding gets harder to lift each day it sits. Rinse the wall from the top down so runoff doesn't leave new streaks. If the yellow stays after a plain wash, let the wall dry before you judge the result.
Before you start
What siding, roof & exterior can take
Safe to use2
- Water
- Oxygen bleach
Use with care5
- Soaking
- Chlorine bleach
- Solvents (alcohol, spot removers)
- Acids (vinegar, lemon)
- Scrubbing and abrasives
7 items
What you'll need
Tap an item to get it on Amazon, or tick what you already have.
- Soft-bristle brush or clothScrubs the siding without scratching it. (opens Amazon)
- White clothBlots the residue without leaving color behind. (opens Amazon)
- Mild dish detergentThe wash for every siding type here. (opens Amazon)
- Garden hoseFor the low-pressure rinse.
- Plastic drop clothProtects nearby plants from overspray. (opens Amazon)
- Oxygen-bleach cleaner labeled for woodFor dark spots on wood only. (opens Amazon)
- Mildew-specific cleaner for fiber cementFor dark spots on fiber cement.
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6 steps
Step by step
Step 1 of 6
Brush off the dried salt
Let the salt dry, then brush or vacuum off as much loose salt as you can. Sweep away leaves and debris around the area as well, so they don't get mixed into the wash.
Step 2 of 6
Blot the residue away
Blot with a white cloth, working from the edges toward the center rather than rubbing. Dampen the cloth with lukewarm water as you go.
Tip. Switch to a clean section of cloth whenever the first one picks up residue.
Step 3 of 6
Test the wash on a hidden spot
Mix mild dish detergent into water and test it on a hidden spot first. Wait for that spot to dry, then check it for dullness or color change before you go further.
Step 4 of 6
Scrub gently with a soft brush
Work the detergent mix over the siding one section at a time. On wood, brush along the grain, and on fiber cement, keep to a soft brush or cloth.
Step 5 of 615 minutes
Treat dark spots as mildew
If dark spots survive the wash, treat them as mildew. On wood siding, apply an oxygen-bleach cleaner in sections, mist it with a hose if it starts to dry, and keep it wet for about 15 minutes before you scrub along the grain.
Step 6 of 6
Rinse off every trace
Rinse thoroughly with a garden hose on low pressure until no soap or cleaner is left on the surface. Blot the area dry, then check the marks once the surface has dried.
Careful. Don't let cleaners or soap dry on the siding, because residue left behind attracts dirt.
If you'd rather buy than mix
Best products for salt stains on siding, roof & exterior
For dark spots on wood, buy an oxygen-bleach cleaner labeled for wood. On fiber cement, buy a mildew-specific cleaner.
OxiClean Versatile Stain Remover Powder
How we picked these: each product is made for this type of stain, its maker doesn't warn against using it on siding, roof & exterior, and its directions fit the steps above.
Finished the steps? How does it look?
Nice work. Let it dry completely and check it again in good light. Here is what done looks like:
How to tell it's really gone →A faint mark usually needs one more round, not a stronger product.
Heavy buildup usually takes more than one round.
Heavy or long-standing buildup →When to call a professional →How to tell it's working
Once the wash and rinse are done, the siding should look even, with no soapy film or dull patch left behind. A mark that's still there after drying is likely set in, so check the set-in section for wood or call a pro for other siding.
What changes for yours
Adjust for your siding, roof & exterior
Vinyl siding
Vinyl takes the gentle steps as written, and it's the least forgiving siding for anything stronger. Keep to water, mild dish detergent and a soft brush or cloth.
Organic-solvent cleaners, liquid grease remover, nail polish remover and furniture polish are all off the table, and so is undiluted chlorine bleach.
Fiber cement siding
Fiber cement gets the same wash, but only a soft brush or cloth, never anything stiffer. A hard metal brush or an abrasive sponge can damage its surface and finish.
Bleach is off the table here. Acid products are off the table too, so on dark spots, use a mildew-specific cleaner with a soft cloth instead of the oxygen cleaner.
Unfinished wood siding
Unfinished wood takes the same wash, scrubbed along the grain with a soft brush. Steel wool and wire brushes leave iron behind that stains the wood, so skip them.
If you pressure wash, use the lowest pressure that cleans, a fan tip, and spray with the grain. Don't scrub hard with caustic cleaners or power wash soft woods like western redcedar, since that strips the wood's surface.
Gray weathered wood siding
Gray weathered wood usually cleans up with the same wash, and the mildew step handles dark spots on it. Expect the wash to clean the surface, not to bring back color that has faded out.
If the wood is silver all the way through, the set-in section explains what to expect. Stronger restorers are only for after the wash has been tried, so start with the wash and see what you get.
Heavy or long-standing buildup
Old stain or sealer on wood is removed with a stain and sealer remover. Neutralize it with a brightener, then lightly sand the wood once it's fully dry.
Reddish-brown tannin bleed or rust streaks on wood call for an oxalic-acid wood brightener, used exactly per its label. The brightener also neutralizes oxygen cleaners, so rinse the oxygen cleaner away fully before you use it. Expect a streak that has been there for years to lighten rather than vanish.
Weathered, gray wood can be brightened with a commercial deck cleaner, brightener or restorer, which removes mildew and dirt so the wood's own color shows. If all of the natural color has leached out, the wood stays silver when dry, and those fibers should be left in place. Expect restoring to bring back color, not to make old wood look new.
Vinegar, baking soda, peroxide and more
Do home remedies work on salt stains on siding, roof & exterior?
Most household remedies from the usual lists don't belong on siding, because salt residue needs a gentle wash and the wrong product can mark the surface. Stick with a gentle wash and skip the rest.
Works2Skip4Avoid1
What makes it worse
Mistakes to avoid
Don't pour liquid onto dry salt
Adding water or cleaner to a dry salt spill before vacuuming or brushing can create additional problems. Clear the loose salt first, then start the wash.
Don't mix bleach with ammonia
Bleach mixed with ammonia, or with a detergent containing ammonia, forms a toxic gas. Check a detergent's label for ammonia before you use it near the siding.
Don't pressure wash fiber cement
A high-pressure power washer can damage fiber cement's surface and finish. Use the garden hose on low pressure instead.
Don't aim a pressure washer upward at vinyl
Never spray vinyl siding from below. Spray from the top down so the water runs off the panels.
When to call a professional
Call a pro if the marks remain after the set-in options, or if the siding is cracked, peeling or loose. Pressure washers can damage siding in the wrong hands, so for high walls or heavy growth, a pro with the right equipment is the safer choice.
Questions
Is the yellow mark from salt water permanent?
Usually not, if you act while the residue is fresh or only lightly dried on. Brush off the dry salt, wash gently, and rinse well before the mark has time to set. Marks that have baked on for a long time may need the set-in options for wood.
What if the mark stays after the wash?
Check whether it's mildew first, since dark spots respond to the oxygen-bleach step on wood. If it's still there on wood, the set-in options are the next step. On vinyl or fiber cement, stronger products are off the table, so call a pro.
Can I use bleach on my siding?
No, skip bleach on siding; a mild dish detergent wash does the cleaning. The mildew step on wood uses an oxygen-based cleaner instead, which is gentler on the siding. Vinyl can't take undiluted chlorine bleach at all.
How do I tell salt from mildew?
Salt usually comes off with the brushing and wash steps, while mildew stays dark and spotty even after the soap wash. If the spots survive the wash, treat them as mildew with the oxygen-bleach step on wood, or with a mildew-specific cleaner on fiber cement.
Will the wash harm my plants?
It can, if spray drifts onto them. Cover nearby plants with a plastic drop cloth, and spray them with water to dilute any overspray.
How long does the job take?
Most of the time goes into brushing, washing and rinsing one section at a time. Only dark spots add the 15-minute wait, since the oxygen-bleach cleaner needs to stay wet for that long.
Salt Stains on other materials
Other stains on siding, roof & exterior
Start from the bigger picture
How we know this
Every method, amount and warning here comes from university extension services, industry bodies and product makers. We read them, check every step for unsafe combinations and changed amounts, and write it up so you can follow it.