Pressure washing concrete

by jared

So, you want to pressure wash some concrete. Must be easy right? After all, it is only concrete and how tough can it be to screw that up right?

Before you start power washing any concrete, there are a few techniques and things you will want to keep in mind. We’ll start out with what type of tip you’ll need to be using the get the best results out of pressure washing your concrete.

Nozzles

In case you’re not familiar with the different tip sizes, there are tip sizes for basically every washing job you could think about performing. The tips change the angle of water as it comes out of the end of the pressure-washing nozzle at the end of the wand.

For concrete, the best nozzle is probably the 15 degree. It is the least amount of fan next to the straight stream. Rarely do I use a straight stream for anything, except maybe knocking down wasp nests from far away.

Be careful when you start spraying and pay close attention to the area your hitting with the high pressure washer. Many times, there will be a slight crack in the concrete which if hit just right with the pressure washer, can turn into a big crack in a hurry.  Always start with the spray pointed away from the spraying service and move it into place after you’ve started the spay with the trigger pulled.

Detergents

I can be sort of lazy, so I really like the detergents that come in the dissolvable packets. I use the Green dissolvable packets from Home Depot. They smell really nice and work fairly well at cutting through grease. You can also come up with your own home made detergent. Depending on what you’re trying to get off the concrete will determine what the of detergent you want, if any. Most often, the concrete I’m power washing is simply my garage and driveway. I love clearing out my garage and going to town with the pressure washer. And for this, the simple soap type of detergent works fine. Leaves the garage smelling good also.

One thing to think about when pressure washing concrete, is that hot water washers work the best. Although they can be a bit more expensive, even to rent, they will cut through the grease a lot better than cold water. Think about the elements that need to be present when washing and how they all work together, heat, pressure, and chemical.

If the concrete or masonry you intend on washing is full of cracks and falling apart, you may want to think twice before going at it with a pressure washer. Unless this is part of your demo process. If you do really need to clean it, try using at least a 40 degree tip which will put less pressure on the concrete surface.

Always start on a little spot to see what effect your washing is having. I generally like to clean a small spot about the size of a basketball then let it dry for 10 or 15 minutes to make sure it's not damaging the surface. This is especially if you're washing concrete with seams or things like floor tiles.

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