Power wash a weathered deck

The cedar deck and pergola at the back of our house had weathered over the years to a lovely silvery patina, but a chance photo taken last summer revealed patches of mildew lurking in corners, and ringed stains where terracotta pots had once stood on the bare wood. I decided it was time for a spruce-up.

After investigating various ways to clean the wood, I concluded power washing would be the best method. Although cleaning solutions designed to lie on the surface and absorb into the wood are good for horizontal areas, power washing meant I could reach the crosspieces of the pergola overhead, as well as the upright posts at each corner of the deck—spots where cleansers would run off. The washer’s wand would also easily reach into the nooks and crannies of the railings. 

These machines, which are as simple to operate as a vacuum cleaner, run on either gas or electricity; electric ones are less powerful (around 1,500 or 1,750 pounds per square inch), while gas-operated machines can blast away at 2,400 psi. For cleaning wood, a lower-powered washer does an efficient job without damaging the surface, especially if you take precautions (see “Power Tips”). Most washers are designed to work with certain cleaning solutions, but I found those unnecessary—and they can be harmful to plants growing around the deck.

Preparation
Clear the area completely of all items, including furniture, barbecues and pots. Close doors and windows. Protect nearby plants by trimming or tying them back, or covering them with tarps or large pots. Sweep up any debris that might get blown around. Now is also a good time to replace damaged or rotted boards, railings and steps, which is important for safety and will help give your deck a new look.

This is a wet job. Before beginning, don waterproof shoes or boots and pants—or plunge in with childlike abandon and pretend you’re at a water park!