How to Remove Dried Concrete From Vinyl Siding

It would have been nice if the workers who poured the concrete walkway around your house had protected the vinyl siding with plastic sheeting, but they didn't, and now it's up top you to remove the now-dried splatters. There's no need for a scenario like this to end in frustration, because in most cases, the removal process is a matter of minimal scraping or scrubbing. Two bad boys are waiting in the wings to handle uncooperative concrete deposits -- a pressure washer and muriatic acid -- plus a not-so-bad solution of plain sugar and water.

Easy Does It

Concrete is known for its adhesive qualities, but vinyl isn't, so in many cases, all it takes a some gentle persuasion. If you happen to get to the concrete before it sets, simply wash it off with a garden hose. If it has set, soaking the concrete with a strong detergent solution helps loosen its adhesion so you can scrub or scrape it off. Georgia-Pacific recommends mixing the following ingredients to make a strong cleaning solution for vinyl siding:

  • 1/3 cup detergent
  • 2/3 cup trisodium phosphate
  • 1 gallon water

Scrub with a soft-bristle brush or scrape with a plastic paint scraper. To give the scraper more leverage, wedge it underneath a concrete deposit and tap it with a hammer; this usually makes the concrete pop off.

When the Going Gets Tough

If you have a concrete deposit that just won't budge, muriatic acid is sure to dissolve it. If, on the other hand, the concrete is spread over too wide an area to make scraping, scrubbing or washing by hand impractical, you can opt for a pressure washer, but check the siding product warranty to be sure you won't void it by pressure-washing. Both options should be considered last resorts.

Using Muriatic Acid

Step 1

Put on goggles and rubber gloves to protect yourself from the corrosive effects of muriatic acid. Mix one part acid with three parts water in a bucket to create a 25 percent solution.

Step 2

Test the acid solution before using it. It's safe for vinyl, but your siding may not be 100 percent vinyl. If it's safe, spread it liberally in the concrete with a natural-bristle paint brush. Don't use a synthetic-bristle brush -- the acid dissolves the bristles.

Step 3

Allow the mixture to dissolve the concrete. It may take several minutes, and you may have to apply more. As the concrete dissolves, wash it off with a garden hose.

Step 4

Clean off the residue with a kitchen scouring pad. Use the pad only after rinsing to avoid dissolving it in acid.

Pressure Washing

Step 1

Set the pressure of the power washer to a value between 1,500 and 2,400 pounds per square inch and attach a 40-degree tip to the nozzle. In a standard set of tips, the 40-degree one is the white one.

Step 2

Start washing at the bottom of the wall and work your way up. Hold the tip about 2 feet from the siding and gradually reduce this distance until the concrete loosens and blows away.

Step 3

Keep the wand horizontal or angled downward. The tip should never point up -- this orientation allows water to get under the siding and soak the sheathing, creating possible mold and rot problems. Similarly, avoid spraying around windows and doors -- the spray can get under the molding.

The Sugar Option

As strange as it seems, sugar can safely remove concrete splatters; it has long been known to retard the setting of concrete and can even dissolve concrete once it has set. Mix sucrose -- white table sugar -- with water; you may have to experiment with mixtures, but as a general rule, the more sugar you include, the better the solution will dissolve concrete. Spray or brush it liberally on the spatter, wait for an hour, then reapply it. Wash off the concrete when it begins to dissolve and fall away. Be sure to rinse off the sugar; you don't want to attract ants, which may crawl under the siding and into your house. You can also purchase commercial concrete removers that include sugar.