How To Clean Mold Off Vinyl Siding- Complete Step By Step Guide

Mold on vinyl siding is the best example of exterior house mold. Moldy vinyl siding makes the appearance of your house unappealing due to its scruffy nature. Modern vinyl sidings are made of plastic polymer, and they are quite long-lasting. As a result, minimal repair is required. But after a year or so, it starts to develop mold and mildew on them due to the moisture it gets over time. Cleaning mold off vinyl siding is smooth & effortless. Paying attention to this step by step guide on how to clean mold off vinyl siding will help to clean it within 20-30 minutes.

Pressure wash vinyl siding mold cleaning
Removing mold from vinyl siding by pressure washer

Why does mold grow on vinyl siding?

The reason for keep getting mold on vinyl siding is natural. The northern exposure of home gets frequent mold, mildew, and moss due to lack of sunlight. The basic thing is that it needs food and water. It gets water from the moisture and food from the surrounding plants, climbing hydrangea, ivy vines, and soil. All these things help mold to anchor in that place. However, the primary factor is the low light facing north exposure, which helps it in the initial phase. Top causes are:

Less sunlight absorbing sides

Most of the people get mold on the north-facing side of their vinyl siding. The main reason is less sunlight. So, this organism gets its primary step set on those sunlight lacking areas as they remain shady most of the time. And there is nothing much to do about it.


Condensation on vinyl siding is a partner for mold. Mold gets flourish over time due to this. High moisture containing areas always get mold on their walls, basement, kitchen, and almost every substance.

The soil on the earth surface

The soil underneath the garden beds surrounding the house is an organic food supplier for mold. In the presence of perfect temperature, air, moisture mold grows naturally.

Leak gutters:

Water leaking from gutters can turn into a potential source for growing fungus and moss. After a long time, it starts to grow mildew on the surface. It also puts simple mildew stains on the area.

Is mold on vinyl siding harmful?

There are 2 aspects of it. One is health, the other is the economy.


Exterior mold is as harmful as interior mold. The drift in the air and its spores can be anywhere. As a result, even if you are just at your garden or at a backspace, those spores can enter your respiratory system and cause many mold-related diseases and health issues. So, it is always good to get it off the siding  as soon as possible.


If Mold stays on your vinyl siding for a long time, it will start to rot the siding as well as discolor it. Soon it siding’s curb appealing will be gone, and under the circumstances, you may end up replacing it.

How to clean mold off vinyl siding?

There are various methods and applications for removing from vinyl siding. The best ones people like to follow have been highlighted:


This method is easyand quite effective. Bleach is inexpensive and also available at local departmental stores. It will kill the mildew as well as other bacteria, grime and will work as a good disinfectant.

1. Take a gallon of water and add 240 ml bleach solution in it. Any kind of bleach will work.

2. Spray it on the siding with a garden sprayer, Cover it. No panels should be left, and no corners should be unwashed.

3. Let it sit for 20-30 minutes, and it will kill whatever germs or dirt associated with it.

4. Finally, wash it with clean water.

5. For heavy layers of mold or dirt, gentle scrubbing with a brush is recommended.


High concentrated Chlorine bleach is a powerful oxidizing agent. So, it may turn out to be fading the color of your siding. Before use, try it on a small portion of siding, let it be there for 10-15 minute, see the change. If nothing happens, then you can proceed.

Trisodium Phosphate

Trip sodiumphosphate is exceptionally effective, all in all cleaner. People use it for both indoor and outdoor cleaning as a renowned agent. You can grab it from local grocery or hardware stores. It comes in powder form. After that, you can make the desired solution by mixing water.  To make a 10% trisodium phosphate solution you need:

1.    Mix a gallon of water with 1 cup of trisodium phosphate.

2.    Then spray it everywhere on the vinyl siding from top to bottom.

3.    Don’t wait after spraying, start to scrub the surface immediately with a long-handled soft brush.

4.    Simple rinsing or washing after that, will take down all the moldy, greasy, and mossy substances.

Dish Detergent-Bleach solution

Bleach with any dish detergent or laundry detergent or powder detergent is effective on mold. The additive detergent will work like a sticking agent to the bleach. Like previously, just add a half cup of detergent with a mixture of 240 ml bleach and water solution.

Garden hose and liquid soap wash

If mold hasn’t been there for a long time, have just started to the depot, then a simple liquid soap solution mixed with water will work quickly. Start washing gently from bottom to top. Don’t miss our eaves. Finally, hose down with normal water. No mopping needed.

Pressure washer

Another useful way to knock out mold from vinyl panels is the pressure washer. Using it on a downward angle over the lap will ensure that water is not penetrating the sheets. It only works on thin layers of mold. On a solid foundation of mold, this technique won’t work. Many found that pressure washers remove the color of their vinyl siding, so before using, try it on a small portion to see the effect.


Read the instructions on the manual to know the optimum pressure for cleaning the vinyl panels. It should be somewhat less than 1600 psi, and the distance should be 12 inches from the vinyl panels. If there is nothing mentioned in the manual, then don’t use it, or it will make the situation worse.  

Oxalic Acid

1.5 cup Oxalic acid with 1 gallon of water will do the work. Spray it with a hose and rinse it off.  However, oxalic acid needs to be handled with caution as it is an acid and will harm if touched directly. So, wearing protective gears like hand gloves, apron, and eyeglass is recommended.

Sodium Percarbonate Bleach (Oxygen bleach)

Sodium Percarbonate is known as oxygen bleach. It is an excellent alternative to chlorine bleach as its final by-product is eco-friendly and biodegradable. When it is mixed in water, it finally produces sodium ash, which is an ecologically sound substance. It is safe for all types of vinyl sidings.

Mix 1 cup of oxygen bleach for one gallon of water. Spray it on the vinyl siding, use a ladder to reach the top exposures of the roof and roof shingles. Let it be there for 15-20 minutes. It will gradually loosen the black mold patches. Then rinse off with a hose, and it’s gone. No smell, no discoloration, and no rubbing. As easy as it can be.

Vinegar Cleaning Solution

According to Bobvila,

A 30% vinegar and 70% water solution works god for cleaning vinyl siding. It will remove light mold and mildew stains smoothly. It is less effective for heavy mold.

How to prevent vinyl siding mold at an early stage?

Mold is a kind of fungi that thrives everywhere with the help of moisture. So, it is tough to find something that will work 100% to get rid of it. There is no coating or chemical which can prevent mold forever. Some easy steps can help to mitigate it in the first place

Regular clean up

Vinyl sidings don’t need any other repair or maintenance other than a regular clean up. Every 3 months after, clean it with dish detergent or liquid soap to keep it sound. By this, any other dirt, grimes, black patches, cobwebs will be gone as well as mold and mildew.

Cut off Climbing vines / heavy herbs

Getting rid of any climbing vines is necessary. They feed mold sugar. Cutting them will definitely reduce the chances of mold growing on your vinyl siding. The same goes for nearby shrubs and herbs.

Inspect the gutter

Gutters need to be properly angled and with no blockage or damage. Especially areas which get heavy rain, this is a really important issue. The right downward angle ensures proper drainage of water. Check the gutter nails also.

Check the Flashing

Flashings need to maintain some standards and rules. Improper flashing results in water leakage and storage under the sheets. Water should drip down through the sidings, without getting intruded behind the vinyl sheets. Otherwise, this intrusion will cause mold under the sheets without any warning

See what’s under the vinyl siding

Check and double-check what’s under your vinyl siding. If there’s wood siding, then check its conditions. If it’s too old, rotted and weathered or molded, it’s better to remove it and only install the new vinyl siding. Remove anything that has mold before putting a new one.

Crawl space and basements

Mold can migrate through inner walls to the exterior ones. Crawl and basement are suitable places for mold growth. As they remain dark and unnoticed. Without a proper air purifier, they ought to have mold. So, keeping crawl space and basements mold free should get into your checklist.

Check the joints /Caulking

Check the sealants and caulking properly. Proper caulking keeps air and water inside. Water penetrates through corners, gets condensed, and produces mold growth. Window, door, and other joints should be sealed properly to prevent the entering of air and water.


Vinyl sidings are expensive. Cleaning mold off siding will not only ensure its longevity but also restore its curb appalling. It isn’t a once and done job. A mild cleaning for 20-30 minutes after every 3-4 months is recommended for every house. The work is simple, no elbow grease needed for this. Try it yourself, if it doesn’t work then call the professionals.

Also read,

How To Remove Mold From Concrete Patio Like a Professional

How to remove mold from wood furniture-A complete guide

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