pressure wash before painting old siding

Should I Pressure Wash My House Before Painting It?

In Exterior Paint, Home Exterior by Jamie

 Sometimes you need to be careful with pressure washing machines as they can easily remove old paint and debris quickly, sometimes causing serious damages. I have used pressure washers to clean driveways, vehicles, decks, and siding. You need to make sure your settings are set for the specific job. In this article we focus on pressure washing before painting siding. So, should you pressure wash your house before painting? 

Yes, you can use a pressure washer to clean your house before applying paint. A pressure washer can help remove old peeling paint, debris, dirt, and grime that would interfere with the adherence of the new paint. However, you should only pressure wash your siding at low pressure and with the correct nozzle to avoid causing damage. 

Let’s take a deeper look into the importance of pressure washing and how to do it properly.

The Importance of Pressure Washing Before Painting

Pressure washing before painting isn’t required, but it does a great job of prepping the surface for new paint. Here are some important reasons why you should pressure wash before painting:

Eliminates Dirt and Debris – The high-pressure water can remove years of dirt and debris that would otherwise take hours of scrubbing.

Helps Remove Old Paint – Not only does the pressure washing remove dirt, but it will also strip off old layers of paint.

Removes Mold & Mildew – Finally, it will blast off mold and mildew, which are two stubborn stains on any surface.

Can A Pressure Washer Damage Your House?

Despite how useful a Pressure Washer is in preparing your house for new paint, it should be used with caution. A pressure washer has the potential to cause damage to the house when used incorrectly. Some things you will want to be mindful of are:

  • The psi being used
  • How close you are to the surface being washed
  • The material your siding is made of
  • Anything in the surrounding area that may become damaged

What’s the Right psi Pressure to Wash a House?

When pressure washing exterior siding, you will want to stay somewhere in the 1000 to 1500 psi range. This will allow you to treat your siding gently and minimize the risk of damage. Keep in mind that while this level of pressure is okay for your siding, it is still high enough to cause bodily harm. Always keep the spray pointed away from yourself and others, as well as wearing eye protection in case of any flying debris.

How Much Pressure is too Much Pressure for Spraying a House

How Much Pressure is too Much Pressure for Spraying a House?

Of course, the type of siding here matters. Wood and vinyl siding can handle more power than stucco, so be aware. Anything under 1500 psi should be safe fore all siding types, just know the condition of the siding is important to consider.

What Damages Can Happen with too Much Power?

Some of the possible consequences of using too high a psi when pressure washing your house include:

  • cracking the siding
  • warping the siding
  • damaging surrounding structures
  • bodily injury
  • causing wood to deteriorate

You’ll notice that I included injury because of excessive power on this list. That is because pieces of the surface you are washing can break off and come flying at you. Always wear eye protection when pressure washing and turn off the machine if you notice cracking. It is common for leaves and sticks to come flying at you if you get close to a gutter. 

Composite Siding

Can You Pressure Wash All Types of Siding?

 

Not all exterior sidings can be pressure washed. Let’s go over some of the most common materials below more in depth.

Vinyl Siding

Vinyl siding is an imitation wood siding made primarily of plastic. It can be pressure washed safely, making it low maintenance. Vinyl siding usually holds up well to water, however it is prone to cracking under pressure and breaking off into sharp pieces. You will want to be extra careful to use the right psi with vinyl. Start low and slowly work your way up.

Wood Siding

Wood siding is versatile and can be pressure washed safely if it is intact. If you notice warping or rotting anywhere on the siding, do not pressure wash this area. Instead, hand wash the damaged area since pressure washing can make it worse. But really, if damaged you should replace the rot and add new wood siding. 

Composite Siding

Composite Siding is similar to wood. It is made from short wood fibers pressed together and bound with resin or glue. It is then finished to look like another material, usually wooden planks. I would not recommend pressure washing composite siding because it can damage the material. Excessing pressure will pull the wood fibers apart and weaken the bonding agent.

Brick Siding

Brick siding, while beautiful, is not a low maintenance siding. If you plan on washing brick with a pressure washer it must be a very low setting so you do not damage the bricks and the mortar.

Cement Siding

Cement siding is usually safe to pressure wash on a low setting. If you see cracking anywhere in the siding, do not pressure wash that area. It will make it worse. Additionally, you will want to get that portion quickly repaired since cracking can spread.

Metal Siding

Metal siding is usually safe for pressure washing. It can be dented by high pressure, so you will want to start slowly to see what it can handle. Remember, the goal is minimum required pressure.

Do You Need a Pressure Washer Cleaning Solution to Clean Your House?

In most cases, water is sufficient to clean the surface. A pressure washer works primarily by pressure, not via a detergent. However, I usually recommend using detergent because it will allow you to keep the pressure washer at a lower setting without compromising on cleaning power. Always use a detergent designed for use in a pressure washer, or you may damage your machine.

Can the Wrong Cleaner Damage Your House?

There are many cleaners on the market, and not all of them will be suitable for your project. Oftentimes cleaners are targeted towards certain kinds of surfaces like stone or metal siding. If you use a cleaner not designed for your siding type, you might cause damage.

The most common damage caused by using the wrong cleaner is that the detergent does not wash off. This will make it a challenge for the paint to adhere to the surface.

How to Safely Pressure Wash Your House Before Painting

How to Safely Pressure Wash Your House Before Painting:

When pressure washing your house to prep for painting, doing so properly is key to avoiding damage and setting your project up for success. Here, I’ll go over how to use a pressure washer with a detergent. If you have decided to only use water, then you can omit the detergent and otherwise follow the procedure.

1. Set Up the Power source 

When setting up your pressure washer, if you have an electric model you will need to find an outlet nearby to plug it in. Choose one with plenty of slack in the cord so you don’t have to pull and tug while you work. For gas powered pressure washers, ensure ample fuel is in the tank.

2. Connect to Your Water Source

Hook up the pressure washer to the water source, usually your garden hose. Do not turn anything on yet.

3. Add Detergent

Add your detergent. Many pressure washers have detergent injectors, consult the manual on your machine for specific instructions.

4. Start Spraying Detergent Solution

Now that you have set up the machine, turn on the water and the machine. Begin washing the surface with the soapy mixture. Use long controlled strokes from bottom to top. This will prevent streaking and missed spots.

5. Let Detergent Sit & Clean Out Remaining Detergent from Machine

Once you have gone over the surface thoroughly with the pressure washer, remove any remaining detergent from the machine and turn it off. Let the detergent sit for 5-10 minutes on the siding.

6. Pressure Wash Using Only Water

Once the 5–10-minute period is over, use the pressure washer without detergent to rinse off the siding. Continue to use long strokes from bottom to top. Feel free to go over the siding once more with only water once everything is rinsed off. You need to make sure no more detergent remains as it can cause adherence issues with the paint. 

7. Let the Siding Completely Dry Before Painting

Let the siding dry. If it is not drying well, you can use a towel to help it along.

How Long After Pressure Washing Can You Begin Painting?

There is no hard and fast rule about when you can begin painting post pressure wash. However, the surface must be completely dry and free from any detergents. If the surface is still damage or covered in cleaner the paint won’t stick. Then, you will have peeling paint and must start all over again. 

If unsure, wait until the next day to begin painting your siding. 

When Should You Avoid Pressure Washing Your House?

Pressure washing your house can be a helpful tool, but its not always the right choice. If you have any holes in the siding where it needs to be replaced, or cracking then pressure washing will exacerbate this issue. It can also send water through the damaged area into the house. This will cause water damage.

You might also consider skipping the pressure washer if you are concerned with preserving an antique material, since these tend to be more fragile than modern siding.

Final Thoughts

Pressure washing is a very useful tool for exterior projects, but it can also carry risk. You can injure yourself, others, or damage your home. Keeping in mind your surroundings, the material of the house, and exercising caution can all help you in your project. Usually, treated wood siding, vinyl, or metal are the safest surfaces to pressure wash.

Masonry and Composite siding are quite delicate and can be damaged easily by pressure. Best practice is always to start slowly and ramp up the pressure until it begins to clean. Never exceed 1500 psi when pressure washing siding, as this will cause damage and is excessive besides.

About the Author

Jamie

Jamie is the founder of The Backyard Pros. When he was 15 years old he started working at a garden centre helping people buy plants, gardening products, and lawn care products. He has real estate experience and he is a home owner. Jamie loves backyard projects, refinishing furniture, and enjoys sharing his knowledge online.