How to Clean Exterior Siding

With the weather getting progressively nicer, now’s the time to start your spring cleaning! Although people often begin indoors, the exterior part of the house should not be neglected.

The exterior siding of your house deserves a proper cleaning to look its best throughout the summer! What are the best techniques to clean exterior siding?

Important Safety Measures When Cleaning Exterior Siding

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In order to work in a safe environment and avoid unfortunate accidents, it is important to always follow these guidelines:

• Find the electrical installations so that you don’t hose them down inadvertently, as this would be a major health and safety risk;

• Avoid using a ladder that is more than six feet high. At this height, it is impossible to eliminate potential accidents when working with a hose, especially considering that your stability is highly compromised;

• Always protect your shrubs and plants when cleaning your exterior siding so that chemical products don’t affect their health;

• If the cleaning technique requires the use of chemical products, wear long sleeves, gloves and protective glasses. This equipment will help protect your skin and your eyes from risks of burning or irritation;

• Do not extend the application of chemical products on the siding, as this may damage it.

How to Clean Exterior Siding: Some Advice According to the Type of Material

Cleaning Aluminum Siding

The first option is to use an all-purpose cleaning product and water. The product will be applied using a pressure washer which will never be used at full force as this would damage the siding.

Another way to clean this type of siding is to use a soft-bristled brush (with the same cleaning solution mentioned above) and rinse it off.

If the stains are too stubborn, the following solution should work:

• 1/3 cup of detergent;

• 1/3 cup of bleach;

• 1/3 cup of trisodium phosphate (which is a strong cleaning and degreasing product). For those interested, this product is also available in a biodegradable version.

If the surface (brushed aluminum or natural aluminum) that needs to be cleaned is oxidized, be sure to scrub it gently with a very fine grade of steel wool (from top to bottom). Avoid circular movements at all costs, as they will scratch the siding.

Cleaning Vinyl Exterior Siding

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For regular maintenance, all-purpose cleaning products are recommended. Follow the manufacturer’s instructions to dilute the product in the appropriate amount of water. It is also possible to use a mix of water and dish soap that you will rinse right after use. Either way, you can easily remove stains caused by sap, dirt or soot by scrubbing with a soft cloth.

For tougher stains, mix 4 litres of water with 1/3 cup of Hertel (or any other comparable cleaning product) and 2/3 cup of trisodium phosphate to clean the siding with a soft-bristled brush.

For mould stains that are on the surface, the process will be completely different. First, the stain should be scrubbed using a soft-bristled brush with diluted bleach. If the stain is darker, combine bleach (1 litre) with a degreaser (2/3 of a cup) and a smaller quantity of all-purpose detergent (approx. 1/3 of a cup).

There are three main practical tips to clean exterior vinyl siding. First, clean from bottom to top by spraying the surface several times throughout the progression of the work, to avoid leaving streaks. Next, use a brush with a long handle to cover a bigger area without having to move. Lastly, never scrub a stain using too much pressure, as you could alter the siding’s finish.

Want to know how much exterior siding can cost? Take a look at our article on the subject!

Cleaning Brick Exterior Cladding

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The first available option is to use a pressure washer. However, make sure that the water jet is never aimed at the mortar joints as they will crumble. Ideally, it is advised to keep the hose about 60 cm away from the wall.

To remove a stain, the use of liquid caustic soda is recommended. This product is the liquid form of caustic soda, a substance that is often used in products to unclog pipes. You can buy this product as-is or in its crystallized form. To transform the crystals into liquid, mix three tablespoons of crystals into four litres of water. Next, apply the product on the siding with the use of a soft cloth and let it sit for 15 minutes. If you are unlucky and the stain still hasn’t disappeared, you will have to proceed with a second application. Don’t forget to rinse with water after each application.

If traces of mould have started to show up on your brick wall, mix two tablespoons of bleach with one litre of water. Apply the mix on the wall and scrub using a soft-bristled brush. Lastly, rinse with water. If there is still some visible mould after, repeat the process a second time and then you should be able to get rid of it all.

Regardless of the option you choose, always start by removing dust from the surface with a vacuum cleaner before you start working.

Although applying a waterproof product can be advisable for certain types of exterior siding materials, with such cladding, it is not the case. This product will trap the humidity on the wall, which will increase the chances of mould forming.

Cleaning Cement or Concrete Exterior Siding

As was the case for brick cladding, it is also recommended to use a vacuum cleaner to remove dust from a concrete or cement surface before cleaning it. Next, go on with the process using a mix of water and washing soda. Do not confuse this mix with caustic soda crystals which are much more corrosive. Carefully follow the manufacturer’s instructions for proper dosage. In the end, rinse the surface completely. 

In this case, applying a waterproof product is recommended if you wish to increase the level of protection of your exterior siding so that it doesn’t experience premature degradation.

Cleaning Stone Exterior Siding

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For this type of material, the best solution is to use a pressure washer. However, since you will have to use a lot of pressure to clean the surface, this technique should be avoided if the walls are weakened.

If you are very patient, mix water and baking soda. Apply it on the surface by scrubbing with a hard scrubbing brush. Like with cement and concrete siding, you can also use a mix of water and washing soda that you will scrub onto the walls using a brush.

Other techniques can be used but can only be carried out by a certified professional. You can choose between:

• Cleaning with a grinder: This is a dry cleaning technique;

• Sand washing: This high-pressure cleaning technique uses sand and is very efficient in removing longstanding dirt. However, this process can cause damage to the siding if not done properly. Always hire a pro for this type of work. Note that this technique is also available for other types of exterior siding such as cement, concrete, brick or wood. Depending on the type of material, the amount of pressure will be different.

Cleaning Parging

Once again, the pressure washer saves the day! To avoid causing damage to the surface, use a low level of pressure. Next, scrub the surface (with a wire brush and not a soft-bristled brush) and make sure to get a brush that is specially made for this type of material.

The water and bleach solution is also very efficient for parging (with a half-and-half mix). Spray the liquid on the wall using a spray bottle and wait at least one hour. It must, however, be noted that this technique is not recommended to use on coloured or pigmented parging.

Cleaning Exterior Siding That's Made of Composite Wood or Real Wood

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The recommended technique consists of cleaning the surface with a pressure washer and a mix of water and soft soap. Since wood is more vulnerable than stone, never use the machine at full strength. 

Cleaning Sheet Metal Siding

To clean sheet metal siding, there are several options available to you. First, in terms of spring cleaning, we suggest using a garden hose to clean simply with water.

For traces of mould, it is recommended to use the following mixture to remove them:

• 1/3 cup of laundry detergent

• 2/3 cup of trisodium phosphate

• 1 pint of bleach

• 3 pints of water

The surface should be cleaned with a soft bristle brush, as previously mentioned in our yearly cleaning procedure.

Have you noticed traces of oil, tar or wax on your steel siding? To remove such stains, note that mineral essence can be very useful. However, after use, be sure to not overlook the second step: washing the surface with soft soap and a soft-bristle brush and finally, rinsing with clean water.

Do you need some help choosing your exterior siding? Check our article Exterior Siding: Which Material Should You Choose?