Prep first
Before you start
- Rinse a fresh splash with plenty of plain water.
- Work in fresh air and wear goggles and gloves when you handle pool chemicals.
- Never mix pool chemicals with each other or with any other product.
- Never add acid or vinegar to chlorine; toxic gas can form.
Chlorine on siding usually takes the color out of the surface rather than sitting on top, so the mark looks like a bleached patch more than a spot you can lift. How much you can recover depends on how fresh it is, and cleaning can't restore color that's already gone. Blue-green marks near pools are a different problem, caused by dissolved copper.
Test any cleaner on a hidden patch of siding first, since a bleached spot can look worse if the wrong product hits it. Knowing whether you have vinyl, fiber cement or wood decides how hard you can scrub. If the patch still looks pale after a careful wash, a pro can tell you whether color can be restored.
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
5 items
What you'll need
Tap an item to get it on Amazon, or tick what you already have.
- Garden hose with a spray settingGives the low-pressure rinse the siding needs.
- Soft cloth or soft-bristled, long-handled brushLifts the mark without scratching the finish. (opens Amazon)
- Household cleanerHandles small spots; choose a plain one and test it first. (opens Amazon)
- GogglesProtects your eyes and skin if you are handling any pool chemicals. (opens Amazon)
- Gloves (opens Amazon)
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5 steps
Step by step
Step 1 of 5
Rinse the siding with a hose
Wet the whole wall with a garden hose on low-pressure spray, working from the top down so the water carries loose dirt away. This clears any pool-water film so the cleaner reaches the mark itself.
Step 2 of 5
Test the cleaner on a hidden spot
Pick a spot nobody sees, such as behind a downspout or under an eave, and work a little household cleaner into it with the soft cloth. Rinse it off thoroughly and check for dulling or color change before you go further.
Tip. Check it once it's dry, since a wet patch can look different from the finished result.
Step 3 of 5
Scrub the stain from the bottom up
Apply the household cleaner to the stained area and work it with a soft cloth or soft-bristled, long-handled brush, moving from the bottom of the mark upward. Keep the strokes light and even so the finish isn't worn.
Careful. Don't let the cleaner dry on the siding.
Step 4 of 5
Rinse before the cleaner dries
Rinse as soon as the scrubbing is done, going a little past the spot so no soap film is left behind. Work in sections so each one is rinsed while it is still wet.
Step 5 of 5
Rinse again and check the color
Rinse the whole wall once more and let it dry in the shade if you can. Look at the spot in daylight: if the color matches the siding around it, you're finished, and if it's still lighter, the color loss is probably permanent.
If you'd rather buy than mix
Best products for chlorine on siding, roof & exterior
Choose a plain household cleaner and test it on a hidden spot before using it on the stain.
Amazon Basics Microfiber Cleaning Cloths
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
The rinse water should run clear, and the spot should match the siding around it when it's dry. A spot that stays lighter means the color is gone, and that won't come back with more scrubbing.
What changes for yours
Adjust for your siding, roof & exterior
Vinyl siding
Vinyl takes the hose rinse and a soft brush well, and that's usually all it needs. Keep organic-solvent cleaners, undiluted chlorine bleach, liquid grease remover, nail polish remover and furniture polish away from it.
Rinse a little past the spot so no cleaner film is left on the panel. Then let it dry before you judge the color.
Fiber cement siding
Fiber cement can be damaged by force and by harsh chemicals, so the hose and a soft cloth or soft-bristled brush are all it needs.
Skip bleach and acid completely, and don't reach for a hard metal brush or abrasive sponge. If the mark won't lift with those gentle tools, stop and ask a professional about the panel rather than trying harsher methods.
Cedar or other soft wood siding
Soft woods like western redcedar lose their surface to caustic cleaners and hard scrubbing, so keep the cleaner mild and the scrubbing light.
Rinse the wood thoroughly after each pass so no cleaner sits in the grain, and let it dry before you judge the spot.
Weathered gray wood siding
Wood that has weathered to silver-gray usually stays that way once it's dry, even after careful cleaning. Scrubbing harder won't push the old color back and will only wear the surface.
Clean it with the same hose rinse and soft brush, and stop once the dirt around the spot is gone. A clean, even silver is a good result here, so don't chase the old color.
Unknown siding material
If you don't know what your siding is made of, use only the hose rinse and a soft brush. Don't guess at a stronger cleaner, because the wrong one can damage the panel.
Check the builder's paperwork, the product label, or the maker's name stamped on a panel to find out. Once you know the material, the matching card above tells you what changes.
Heavy or long-standing buildup
An old chlorine mark has usually taken the color out of the finish, and cleaning can only lift the dirt and residue around it. Start with the steps above before you consider anything else.
If the spot has dried hard, give it a longer hose rinse to soften the residue before you brush, and keep the scrubbing light. No stronger siding treatment with exact amounts is safe to recommend here, so don't try one.
If the spot is still there after that, the color is most likely gone for good. A professional can tell you whether the panel can be refinished, which is a better next step than a harsher cleaner.
Vinegar, baking soda, peroxide and more
Do home remedies work on chlorine on siding, roof & exterior?
Most household remedies you'll find online are written for fabric, stone or wood decks, not siding. A hose, a soft brush and a household cleaner are all siding needs, so most online remedies add nothing.
Skip5Avoid1
What makes it worse
Mistakes to avoid
Don't scrub with steel wool or wire brushes
Leftover iron from these tools can react with wood and leave streaks. A soft cloth or soft-bristled brush does the job without that risk.
Don't blast it with a power washer
High pressure can damage fiber cement and wood, and on vinyl a washer should never be aimed upward. A hose on low-pressure spray covers every step here.
Don't mix bleach with ammonia
Mixing bleach with ammonia, or with any detergent that contains ammonia, forms a toxic gas. Read the label on every cleaner before you use it, and never combine two cleaners.
Don't keep scrubbing for the color
Chlorine usually takes color out of the surface, and that loss is generally permanent. More scrubbing only wears the finish, so stop once the dirt is gone.
When to call a professional
There's no clear point where siding needs a pro for chlorine marks. If the finish looks damaged or the mark is still there after these steps, a professional can look at the panel before you try anything stronger.
Questions
Can chlorine stain siding?
Usually it doesn't add a mark; it takes the color out of the siding, so the spot looks lighter or duller than the rest. Rinse the area first, then clean it gently, since the lost color is usually permanent.
Will bleach fix a chlorine mark on siding?
No, since chlorine has already taken the color out, adding bleach mostly adds risk. Vinyl can't take undiluted chlorine bleach, and fiber cement can't take bleach at all. Chlorine has already taken the color out, so adding more bleach mostly adds risk.
What causes blue-green marks near a pool?
They usually come from dissolved copper, often from corrosive water attacking copper plumbing. That's a different problem from a chlorine splash, and the steps here won't remove it.
Can I use a pressure washer on chlorine marks?
Use only a garden hose on low-pressure spray for the rinse. High pressure can damage fiber cement and wood, so the hose is the safe choice for every surface here.
How do I know what my siding is made of?
Check the builder's paperwork, the product label, or the maker's name stamped on a panel. If you still can't tell, use only the hose rinse and a soft brush, and don't guess at a stronger cleaner.
Will the color come back after cleaning?
Usually not. Chlorine takes color away, and cleaning removes the dirt around the spot, not the lost color. If it still looks lighter when dry, a professional can look at the panel and tell you your options.
Chlorine 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.