Can You Pressure Wash Stucco?


Things to consider before power washing stucco

Inspect the surface of the stucco

Before power washing stucco, the first thing that you need to do is inspect the surface of it for any cracks or gaps.

This is particularly important as water can get into the stucco through the gaps, which could cause water damage in the walls or cause mold and mildew to begin to grow as damp areas are the perfect spot for them to live.

Seal any cracks

If there are any gaps in the stucco then you must repair them before you pressure wash it. Small areas of damage, such as hairline cracks can easily be repaired with little trouble.

To repair hairline cracks or small chips in the stucco surface then you should use exterior acrylic caulk that is similar to the color of the stucco.

You should apply the caulk to the damaged stucco to cover the gaps or chips and then use sand or something similar to give it the same texture as the rest of the stucco. To do this, you should press the sand onto the caulk before it dries.

Once the caulk has dried then you can begin to wash the stucco. However, if there is a lot of damage to the stucco then you should call a professional in for help.

Stucco needs precise PSI

It’s quite easy to damage stucco when washing it if you’re not careful – areas that have already been damaged are susceptible to more damage if washed with high pressure.

When using a pressure washer, each different surface you wash has its own ideal range of pressure per square inch (PSI).

Surfaces such as concrete can cope with a harder PSI than shingle roofs which must have a lower PSI used so that they don’t get damaged by the pressure washer, while stucco is in the middle region.

When washing stucco you should use 1,500 to 2,000 PSI, but it should be less if the stucco is damaged or is especially textured, and a lower pressure should be used for the first round of soap.

Stucco is actually quite a delicate material and if you use a pressure that is too high then you could easily damage it.

You should also use a nozzle that is 25 or 40 degrees when pressure washing stucco, and there should always be at least 24 inches between it and the stucco.

To minimize any damage that might occur when washing the stucco surface, you should rinse it at an angle of around 45 degrees.

Incorrect chemicals can cause damage

It’s easy to damage stucco, and not just with too much pressure, as you can also damage it by using incorrect chemicals or cleaners.

Often, people resort to cleaning products if the stucco has dirt deep inside any cracks, or rust and oil engrained onto its surface since washing alone is unlikely to remove it all.

However, care should always be taken to use the correct products as chemicals that are too strong or are left on the stucco surface too long can cause it to become discolored or even weaken the material.

What is surrounding the stucco surface?

You should always try to protect the areas and surfaces that are surrounding your stucco when using a pressure washer as they can easily become damaged too.

High-pressure water and cleaning products can easily kill off plants concrete can often absorb the runoff from the chemicals you are using.

A guide to power washing stucco

Patch up any damage

First of all, you need to patch up any damage that you find in the stucco. Pre-mixed stucco patches are readily available and are ideal for the job.

Although it might be quite difficult to exactly match the color of your stucco patch to the existing stucco you shouldn’t worry too much as over time it will blend in with the existing stucco.

You should always allow the patch to dry completely before pressure washing – usually for around one week.

Apply cleaning solution

The best way to apply a cleaning solution to your stucco is with a spray can, unless your pressure washer has a detergent dispenser, although if that is the case then you should only use it on a low-pressure setting.

The cleaning solution should be a mix of liquid soap and water, although if there is mold on your stucco then you should use a mixture of bleach and water in equal parts.

If you wanted to, then you could use concentrated stucco cleaner mixed with hot water or bleach. If you are using bleach then always remember to take the appropriate safety precautions and wear goggles and rubber gloves.

However, if you don’t want to use bleach then soap mixed with Borax is a good alternative as Borax is not as toxic as bleach but will still remove mold.

This solution should be made up of 1/2 cup of Borax, 2 gallons of warm water, and 2 tablespoons of liquid soap.

To clean the stucco, you should apply your chosen cleaning solution to the stucco one section at a time and always work from the bottom to the top.

Leave the solution on the stucco for five to ten minutes, but it should not be allowed to dry. If that starts to happen then wet it again with the spray can or with the pressure washer on a low setting.

Pressure washing the stucco

You should now adjust the setting of the pressure washer so that it is 1,500 – 2,000 PSI and then test it on a small and inconspicuous area of the stucco to see if it on the correct setting.

Once you are sure that it is on the correct setting you can begin to wash your stucco. Always keep the nozzle at least 24 inches from the surface of the stucco and use it so that the stream of water is at an angle of approximately 45 degrees. This should avoid damaging the stucco with the water.

Use the pressure washer to rinse the cleaning solution off the stucco and work from the top to the bottom in sections. Always avoid going too close to windows as they could be damaged by the pressure washer.

Stubborn stains

Often, there will be some stubborn stains that require more cleaning solution to remove them. For these, you should use a cleaning product that is suitable for removing the type of stain that you have – rust, oil, etc.

Scrub the area with the cleaning solution and a soft brush before using either a garden hose or the pressure washer to rinse away the stain and cleaning product.

Graham Walsh

I want to share everything I know about home improvement in order to help you. Whether you're a home enthusiast or an industry professional, I have the information that you need.

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