Ask the Carpenter: How to clean siding without a pressure washer

Ask the Expert Home Improvement
The best way to clean siding is the old-fashioned way -- with sudsy water and elbow grease.
The best way to clean siding is the old-fashioned way -- with sudsy water and elbow grease. indyedge

Pollution, dirt, and mold are common problems with all types of house siding. Sometimes siding that looks as if it needs a new coat of paint really needs only a good scrubbing. The most time-consuming — but thorough — way to wash it is the old-fashioned way: with a bucket of sudsy water, a nozzle hose, and a soft-bristled nylon scrub brush screwed onto the end of a pole.

Pressure washers can do this job faster, but they are not as thorough and can damage the siding and finish. If you go this route, learn how to use a pressure washer properly. (I’ll cover this in an upcoming article.)

Items needed:

■ Soft-bristled nylon scrub brush

■ Extension pole

■ Bucket

■ Hose

■ Spray nozzle

■ Bleach

■ Trisodium phosphate (TSP) detergent

■ Ladders

■ Mildewcide, if needed

How to wash your house:

If mildew is present, use a solution of 1 quart of bleach to ¾ gallon of water and a small amount of the TSP detergent. (Paint dealers also sell mildewcide that can be used to clean wood siding.)

■ Turn off the power to any outside lights that could get wet.

■ Remove any items in the way.

■ If you have shrubs or flowers in the area, cover them with plastic so no cleaning solution gets on them.

■ Close windows and vents.

■ Put on eye protection and gloves, and be careful on the ladder.

■ Wet the siding, spraying in a direction away from doors and windows.

■ Scrub the areas with a soft-bristled brush on the end of an extension pole, working in small sections at a time.

■ Start at the top and work your way down; this allows the dirt to wash down and keeps the bleach from staining.

■ Rinse the cleaning solution off the siding before it dries.


Dear Rob

From Debbie in Andover: You answered my question about refinishing a mahogany exterior door (“How to give cedar siding of various ages that uniform look,’’ Feb. 14). I wanted to let you know that I finally tackled the project, and it looks great! I used the Cabot product you recommended and sanded the living daylights out of the door and sidelight before applying the product. I did the door a few weeks ago (it is protected by a storm door), but waited on the sidelight until I was certain the pine pollen season was over. Thanks again.

Sidelight before. —Handout
Sidelight after. —Handout

From Carol in Carver: Hi, Rob. Read your column about how to get rid of old paint (“How to dispose of leftover paint,’’ June 21). You forgot one step. You can buy a package of paint hardener at the store. Very easy. I just did it with a couple of cans, but I didn’t know about not putting the top back on. Enjoy your column. Even though I’m 80, I still do things around the house.

Rob Robillard is a general contractor, carpenter, editor of, and principal of a carpentry and renovation business. Send your questions to or tweet them to @robertrobillard. Subscribe to the Globe’s free real estate newsletter at