How to Pressure Wash a House Before Painting

Mar 9, 2020

Your house is more than a house – it’s your home. Just as the inside of your home should feel clean and inviting, the outside of your home should have the same effect! If your home’s exterior is starting to look dingy and neglected, freshen it up with new paint.

It’s important to note that painting the exterior of your home is a time-consuming process. If you’re going to paint your house, make sure to do it correctly. Pressure washing is a key first step to making sure the new paint job looks great and lasts as long as possible.

Pressure washing your house is more complicated than just giving it a good rinse. Here’s a look at how to properly pressure wash a house before painting.

What is pressure washing?

Pressure washers are machines that spray water using a high level of pressure. The force of the water is enough to remove dirt, dust, mold, mildew and more from your house’s siding. Depending on the condition of what you’re trying to wash, you can use pressure washers with water alone or with a detergent. The amount of pressure used can also be adjusted, as can the width of the water being sprayed.

Pressure washing is an effective way to clean your house’s siding – including wood, vinyl, stucco and more – and is able to remove more dirt and grime than a simple garden hose can. It also prepares your house’s exterior surfaces for new paint. In addition to cleaning siding, pressure washing can be used to clean decks, patios and fences.

Why is pressure washing important?

Before you start painting your house, you want to make sure that the siding is prepped and ready for new paint. If you don’t pressure wash your house before painting, there will likely be dirt and dust stuck to the siding. Paint does not adhere to dirty surfaces as well as clean surfaces, so pressure washing before painting is a key step to achieving a quality paint job.

If you try to paint over dirt and dust, the paint may bond with the dirt instead of the siding, causing the paint to later flake off. It may also prevent the paint from properly drying. In addition to dirt and dust on your siding, you may also run into the issue of chalking, which is when a powder forms on the paint’s surface, making it difficult for new paint to stick. You may also have mold or mildew. Painting over mold won’t kill it, and it may actually continue to grow underneath the paint and show visible signs that the problem still exists.

In addition to helping remove dirt, dust, chalking, mold and mildew, pressure washing can help remove bits of old paint that may be stuck to the siding, although you won’t want to use this as your main means of paint removal. Pressure washing before painting helps ensure that the paint properly adheres to the siding, has a smooth finish, and won’t need to be redone sooner than anticipated.

How to pressure wash a house before painting

Before pressure washing the house, make sure you understand how to prepare for an effective washing. When you’re ready, follow the necessary steps to ensure your pressure washing is done right and the new paint looks great.

Understand the basics

Pressure washing is a simple concept, but there’s a lot involved when it comes time to actually get started. Before power washing your home’s exterior, it’s important to be familiar with these features and best practices.

Amount of pressure: There are two ratings to look at to determine your pressure washer’s pressure level: Pounds per Square Inch, or PSI, and Gallons Per Minute, or GPM. The higher the number is, the stronger the water pressure.

There are a variety of factors that affect how much pressure you should use when pressure washing, including the material of the siding and whether you’re rinsing or cleansing. For example, some materials such as certain types of wood may be softer than others, and using too much pressure could damage them. You’ll also want to use less pressure when applying detergent to the siding than when you’re rinsing with clean water. You can adjust the pressure level on your machine or by standing closer to the siding to increase the pressure or moving farther away to reduce the pressure.

Spray nozzles: Using different nozzles allows you to adjust the water pressure as well as the degree of angle at which the water is sprayed. Nozzles are available in different colors and degrees: Red: 0 degrees (this should typically not be used on siding); Yellow: 15 degrees; Green: 25 degrees; White: 40 degrees; Black: 65 degrees. You’ll typically use the black nozzle when applying detergent and the green or white nozzles when rinsing.


Before power washing, there’s some prep work that needs to be done to make sure the siding is ready to be washed. For example, if the siding has old paint that’s chipping, cracked, or peeling, you’ll need to scrape, sand and smooth the surface before washing. While pressure washers can clear off small pieces of old paint, they are not meant to be used as the main paint removal method.

Fix any damaged areas you see and replace nails that have come loose as well as any wood that has become rotten. If you notice areas with mold or mildew, be sure to treat them with bleach to clean them up and to help prevent future growth. If you live in an older home, test for lead paint. In the case you do have lead paint, it’s best to forgo the pressuring washing. If you have plants nearby, protect them by covering them with a plastic cloth. Make sure you’re aware of electrical components like lights, outlets and wires, and keep the water stream away from these at all times.

Protect your eyes by wearing safety glasses, and wear gloves to keep your hands safe. Wear shoes that cover your feet and clothes that cover your legs and that you don’t mind getting wet. Gas pressure washers can be noisy, so consider wearing hearing protection if you’re using this type of washer.

Once you’re familiar with your pressure washer components and have everything prepared, it’s time to begin washing.

Rinse first

The first step when pressure washing a house is to rinse the siding using your power washer and clean water. This will help to remove larger debris. Start by standing about 10 feet away from the wall, then move in closer for more pressure, if needed. Be sure that you’re not standing with the water so close as to cause damage to the siding. Spray the water from side to side, moving from the top of the wall to the bottom. Be sure to hold the wand so that the water sprays the siding at about a 45-degree angle. Do not spray windows, as this could break them.

Use a cleaner

Next, add detergent to your pressure washer. Again, start by standing away from the wall and move in closer if more pressure is needed. Apply detergent to the siding starting at the bottom of the wall and moving your way up to the top. Low cleaner pressure should be sufficient, and using a wide-angle (such as provided by the black or white nozzles) will work best during this step. When possible, use a downward angle while spraying; this will help keep you from getting water into the seams of the siding. Leave the solution on for about 10 minutes. It’s best to wait to do this step when it’s not excessively hot outside and when the siding is not in direct sunlight.

Rinse again

Finally, rinse the siding thoroughly with clean water, working from the top of the wall to the bottom to prevent dirty water from running over areas that have already been rinsed. Use high water pressure during this step.

What happens after pressure washing?

The pressure washing may be done, but don’t reach for the paint can just yet. Depending on the weather and the material of the siding, it may take 2 or 3 days for your house to completely dry before painting. For example, wood siding takes longer to dry than vinyl siding. However, you also don’t want to wait too long before house painting, as dirt can build up again in that time.

It’s important to also scrape off any remaining loose paint so that your siding is a smooth canvas for the new paint to stick to. If you accidentally damaged any wood while power washing, be sure to fix it before painting. When pressure washing and painting are done correctly, you shouldn’t need to paint your house again for a couple of years.

In order to keep or increase their value, houses need to be properly maintained. Painting the outside of your home is a great way to improve curb appeal as well as protect the house’s exterior from volatile weather. However, before you start painting, it’s crucial to pressure wash the siding. Pressure washing is an effective way to clean your home’s exterior surfaces and help preserve your home, as it removes dirt, mold, mildew and more.

While it’s possible to pressure wash your house yourself, there’s a lot to consider. Will you buy a pressure washer, or rent one? Will it be gas or electric? How well do you understand the different nozzles and when to use them? What about angles, distance, and patterns of spraying? And do you know which detergents are safest? Professional painting companies have the right equipment and know-how to get the job done in the best and most efficient way, so it just makes sense to leave it to the experts. Classic Papering & Painting has been in business for more than 25 years. With quality craftsmanship and an unparalleled reputation for attention to detail, we’ve grown to be one of the most recognized and trusted companies in the Columbus, Ohio area.