Some people just don’t realize what a “prize” an old stone retaining wall is on their property. Rather than let this part of the story deteriorate, it should be maintained or even ‘tweaked’! A thorough cleaning of an old stone retaining wall can bring it back to life and once again add beauty to your garden and landscape.

You have to be bad at cleaning! – Old stone walls have years of soot and mold buildup. These stains can be difficult to remove depending on how deep the mold and soot has penetrated. There may also be fungal and algae growth, as well as vines or ground cover that take root in the wall. So what needs to be done? Well, you realize these parasites have got to go! So let’s break out the pressure washer and get ready to clean up!

Use a medium size pressure washer – Is the pressure washer ready? OK good… now… STOP!! The worst thing you can do right now is turn on the pressure washer and blow out all the joints with a high pressure sprayer!

Also, if you start cleaning the wall without properly soaking it, you will only push the surface soot deeper into the wall pores through the action of the wick, making it harder to clean… like this! hold your horses! No… the approach that I am going to explain to you is a little more subtle and gentle.

Ok, now start the cleaning process by first saturating the wall. This is achieved by gently washing the wall with a wide angle nozzle. Move away from the wall maybe 3′-4′ and let the water flow around and run down the face of the wall.

Your wall is now completely soaked, which will allow the detergent to penetrate deeper into the wall system and remove soot and grime. Also, a saturated wall will prevent the detergent from drying out prematurely, giving it plenty of time to do its job.

The trick is to use a commercial grade degreaser. – Now apply a concentrated heavy duty degreaser purchase from a commercial pressure cleaning supply company. Do not dilute. Pour the detergent directly from the bucket into a garden sprayer and start spraying the wall. Make sure every inch of the wall is covered and try to maintain a “wet look” as you go. This degreaser will cost a few dollars, but this is not the place to skimp. If you want to clean the wall buy the degreaser… simple.

Now it looks even worse! – Ok, now the wall has been soaked and degreaser applied, so what do you do? You wait. That’s right… wait.

After about 10-15 minutes, the wall will start to turn a deep amber color and then a dirty brown. You will see streaks of grime dripping down the face of the wall. The wall will look terrible and you will be worried that you will ruin it! That’s good. As soon as you start to feel like it’s a lost cause and you’re ready to throw in the towel, you’ll know your job is almost done!

Now that the degreaser has had a chance to work lifting the dirt, it’s time to shake it up like a washing machine. Using his 15-degree nozzle, he starts hitting the wall with quick, random, up-and-down motions. This time you are not looking to saturate the wall. When you see soap suds appear from the pressure of the sprayer, move up and down the wall and continue along.

You can do this a couple of times along the wall to get the deepest possible clean. This agitation will dilute the degreaser to a lower viscosity and create soap bubbles that will lift soot and dirt from the surface.

Ok… now you can fly it! – Once the degreaser has been stirred up, you can now proceed to the final step of power washing the wall. Starting where you first applied the degreaser, position the wand 12″ to 16″ from the face of the wall.

You clean by watching the soot rise off the wall as you move the nozzle from joint to joint and stone to stone. You will see the soot and dirt disappear as you go down the wall. If a section later seems to be drying too quickly, shake again to keep it moist until you can get to that section.

You’ll be amazed at how quickly years of soot, dirt, mold and debris are removed. Stubborn stain areas may require another application.

When you’re done, you’ll recoil in amazement! That dirty old wall will look new and refreshed and your work will be complete. After all that hard work, sit back and enjoy the beauty of your refinished wall…after all, you deserve to relax!