Can Pressure Washing Damage Concrete? (How to do it Safely!)

Homeowners often find themselves looking at their dirty driveway and realizing how satisfying it would be to get out the pressure washer and clean it. Is this safe to do? Can pressure washing damage concrete? 

The answer is YES, without proper equipment and knowledge, you can damage your concrete!

Here are a few things to consider before taking on this task…

What is the age/condition of the concrete?

It is important to consider the age of the concrete before attempting to pressure wash it. 

If you have a brand new driveway that has not completely cured, pressure washing often can damage this and is not recommended. The curing process can take anywhere from 6 months to 1 year and should only be approached with light rinsing during this time. 

If your driveway is old, eroding, or cracked, pressure washing can often further this damage and should be approached with caution. 

How much pressure am I using? 

Many homeowners own their own pressure washers, varying in size, capability, and attachments. If you do not know exactly what the equipment you’re using is, you may unintentionally damage your concrete. 

The Nozzle you use typically is the most common issue in regards to damaged concrete. If you use a nozzle with a narrow spray it will leave etch marks in the concrete that are very difficult to fix. Here is an example of a sidewalk we looked at after someone had tried cleaning with the wrong nozzle:

These etch marks were left on a new sidewalk. This is easily avoidable with the correct equipment!

The amount of pressure you use is also important to consider when cleaning concrete. Concrete takes more pressure to effectively clean. We are typically using anywhere from 2400-3200 psi and have had much success at this level.

Here’s a before and after of a concrete cleaning we did this past year

When should I do this? 

While we know you want to keep your home looking its best, it’s not recommended to pressure wash anything too often. If concrete is excessively pressure washed, you can ruin its bond and speed up the aging of the concrete. 

We generally recommend a once-a-year cleaning for most residential driveways. Commercial drives and walkways may require more frequent cleaning depending on required standards and codes. 

How to do it safely

Now that you know what to consider before starting this task, we want to explain how you can do it safely and effectively! 

This task can be time consuming. Most residential driveways take us anywhere from 2-4 hours to complete.

Here is how we typically approach cleaning:

Rinse off the surface of the driveway prior to your cleaning, it helps to clear the driveway of any loose debris or caked up dirt. Doing this helps ensure you are getting to the concrete when you start your high pressure cleaning.

Apply chemicals if necessary to get your concrete clean. While chemicals are not required to get your concrete clean, they do help get deep staining to look better. If you are wanting to remove oil or grease staining, a degreaser of some kind is recommended. If you are cleaning organic growth or dirt, Sodium Hypochlorite is a commonly used industry chemical. Chemicals can be applied in a number of ways, typically with a pump-up sprayer or through a chemical injector on your pressure washer. It is important to research any chemical you decide to use ahead of time in order to ensure safe and proper application.

Start your high-pressure cleaning on the topside of the concrete. You want the water and dirt to rinse downward away from what you’ve already cleaned. We recommend using a 25-degree nozzle, holding the nozzle around 12 inches from the concrete, you want to make a smooth sweeping motion to ensure even cleaning. You will do this back and forth across your driveway until you finish. Sometimes it can help to do the same thing perpendicular to the direction you have already gone, to ensure a thorough cleaning. 

Rinse off any lingering dirt or debris, this also helps the surface to dry evenly. You will not see your full results until it is totally dry! The feeling of accomplishment and satisfaction of this task can be very rewarding, but it will require some patience before you make it there.

Professional cleaners commonly use tools such as surface cleaners, soft wash systems, and high-speed turbo nozzles to efficiently and effectively complete this task for homeowners. If this task sounds like more than you want to take on, they will already have the equipment and information needed to do this safely for you.

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