How to Pressure Wash a Deck

Overview

If you’ve been putting off renewing your deck because you think it requires a lot of time, tools and know-how, take heart. In this article, we’ll show you how to clean it up fast with the help of a pressure washer and special products that help remove dirt, mildew and old finishes. We’ll also show you how to apply a fresh finish, using a foam applicator pad that glides along the wood and quickly applies a nice, even coat. No more messy rollers and brushes.

This process will work on any wood deck, including redwood, cedar and pressure treated lumber (but not on composite decks). The only special tools you need are a pressure washer and a foam applicator pad. The project doesn’t require any special skills. Just set aside at least four hours on one day to clean your deck, and another four hours several days later to stain it.

The cost of rejuvenating an average-size deck is about $250, including tools, materials and the pressure washer rental. You’ll save several hundred dollars by doing the work yourself. Having your deck professionally cleaned and stained will cost $500 to $1,000.

Rent a pressure washer

A pressure washer will scour away dirt and contaminants ingrained in the wood at the same time it sprays on a deck stripper to clean off previous finishes.

Rent a pressure washer deck cleaner from a home center or rental center (about $40 for four hours, or $70 per day). A pressure setting of 1,000 to 1,200 psi is ideal. Too much pressure will damage the wood and make the wand harder to control.

Rent a unit that allows for the intake of chemical cleaners (deck stripper and wood brightener) so you can spray them on through the wand. Most pressure washers have an intake hose that draws in cleaners from a separate bucket. (Use a plastic bucket. Chemicals in the cleaners can react to metal buckets.)

We used sodium hydroxide as the deck stripper. You probably won’t be able to find straight sodium hydroxide, but you can find a deck stripping product with sodium hydroxide as the active ingredient in almost any home center or paint store.

We diluted our stripper to a 50/50 mix with water. Some sodium hydroxide–based strippers are premixed and don’t require adding water. More commonly, you need to dilute the stripper with water. Read the label on the container to find out what’s suggested for your stripper.

Protect your house and plants

Before you begin cleaning, make repairs to your deck, such as replacing cracked or split boards and broken balusters.

Then heavily douse the plants or grass under and around your deck with water and cover them with plastic. Although most strippers aren’t supposed to harm vegetation, it’s still a good idea to protect plants and it only takes a few minutes. Once you’ve finished cleaning the deck, immediately remove the plastic.

Also spray down the siding with clean water to ensure that any stripper that splashes onto the house will easily wash off.

Scour away the old finish

Clean the railings

Pressure-wash the railings with stripper. Keep the tip 6 to 10 in. from the wood and work from the top down. Spray balusters at the corners to scour two sides at once.