Cleaning the outside of your home regularly using proper detergents and a low-pressure spray makes it look a lot better and can also preserve and prolong the life of the structure. (Photo courtesy of

When was the last time you cleaned your house? No, not inside. I mean, have you looked at the outside lately?

Like debt and middle-age weight gain, outdoor house filth creeps up gradually. You ignore it because  getting your house washed, at least on my list, ranks pretty far down – somewhere between filling out your do-not-resuscitate orders and replacing the transmission fluid.

I called Jeff Worth, owner of Tropical Roof and Exterior Cleaning Systems, based in Longwood, Fla. Worth has been cleaning roofs and house exteriors since 1998, so wasn’t the least bit fazed when I told him about black creep that was inconveniently forming on our covered outdoor patio and in other dim, damp recesses around the house.

I sent him some photos and we agreed on a price and the soonest possible date for a cleaning. But I wasn’t done with him yet.

Whenever I run into someone who has done one kind of home improvement for 20 or more years, whether the expert installs tile, builds entertainment centers, or hangs wallpaper, I start asking questions:

  • How often should people have their houses washed? Most people know when their house needs a cleaning by looking at it. If the window sills and door frames are full of dust, the roof is dripping black filth down the walls, the light fixtures are covered in cobwebs, and the eaves are crusted with wasp nests, it’s time. If you live around a lot of trees or on a lake, you’ll need cleanings more often. In general, Worth recommends every 12 to 18 months.
  • Why is it important? If you don’t clean your house’s exterior regularly, nature will take over and the structure will deteriorate. Mildew and mold, once it gets hold, can damage your paint. Proper cleaning can prolong and preserve the structure, improve curb appeal, increase your own enjoyment of the property, and rid the house exterior of insect debris, eggs and cobwebs. Sold.
  • What’s included? A good exterior cleaning service will wash the facia, soffits, walls, windows, entryway, and the outside of the gutters. The roof is separate.
  • What is the best process? Most industry professionals use a biodegradable, bleach-based agent that includes a detergent disinfectant that kills algae and fungus, said Worth. They apply the solution and rinse it off using a low-pressure (100 psi) “softwash.” Companies that claim to have a “chemical free” process often have to blast the house with pressure as high as 4500 psi, which can harm the house. Though the cleaning process is fairly universal, the stuff growing on houses isn’t. The hot, humid Southeast has more mildew and mold, while the Northwest, where climates are moist and cool, has more lichen and moss.
  • How do you find a good company? Look for licensed, insured professionals who specialize in washing house exteriors and roofs, and who have been in the business a long time, said Worth. “Don’t hire your lawn guy, landscaper or painter to do the job. They may have pressure-washing equipment, but not the knowhow.” Get a recommendation from someone you trust. Check online reviews.
  • What could go wrong? A company that doesn’t get the mix right could leave streaks in your paint, and burn your plants. If they use too much pressure, you could end up with water intrusion.
  • What about the plants? Cleaning solutions mixed in the proper ratios won’t hurt the landscape. Don’t wrap shrubs in plastic, warns Worth. That will kill them.
  • What do you wish more people understood about the service? Power cleaning a house is not a substitute for professional pest control, window cleaning services, or painting prep.
  • How much does it cost? Though costs for exterior cleaning vary by region and season, the average is between 10 to 17 cents a square foot. So a 2,000 square foot house could cost between $200 and $350. Custom stone work, pool patios, pavers, awnings, screened in patios, and roofs, are usually additional.
