From 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 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 (see Buyer's Guide, below).
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
With a 25- or 30-degree tip in the wand of
the pressure washer and a psi of 1,000 to
1,200, apply the stripper to the deck, starting
with the top rails and working down the balusters (Photo 1). Spray the rails
with a continuous, controlled motion.
Keep the wand moving so you don't gouge
the wood.
Once you finish the railings, start on the deck boards.Wash along the length of the boards (Photo 2). You'll see the grime washing off the wood.
Go over stubborn mildew or other stains a few times rather than turning up the pressure or trying to heavily scour the wood. Later we'll tackle tough stains that won't come out with the stripper.
This stripping process washes away a small amount of the wood's lignin, which is the glue holding the wood fibers together. As the lignin washes away, the fibers stand up, giving the wood a fuzzy appearance. Don't bother sanding off the fuzzy fibers. They will gradually shear off and blow away.
After you've power-washed the entire deck, rinse all of the wood with plain water to dilute and neutralize the stripper. If there's still debris trapped between deck boards, such as leaves or twigs, remove it now (Photo 3).
1. 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.
Click Image to enlarge.
2. Spray one deck
board at a time,
using a gentle sweeping
motion. Avoid sudden
stops. Work from the end
of the deck toward the
exit. Then rinse the entire
deck with a garden hose.
3. Dig out trapped
debris from between
deck boards with a putty
knife. Spray the deck
lightly with a mixture of
oxalic acid and water to
brighten the wood.
Brighten the wood
A deck brightener will return the wood to
its newly sawn color and make it more
receptive to the stain. Use an oxalic
acid-based brightener, which is available at
home centers and paint stores (see Buyer's
Guide). It works fast, won't harm the
wood and is environmentally safe in the
diluted solution that you'll use.
Like strippers, some deck brighteners come premixed and some need to be diluted with water. Read the label for the manufacturer's recommendations. We mixed our oxalic acid with an equal amount of water and ran it through the pressure washer's intake hose.
Change the tip in the wand of the pressure washer to a fan tip with a 40- or 45-degree angle. Then set the pressure to about 1,000 psi and spray the deck, once again starting with the top rails and working down to the deck boards. Apply just enough brightener to thoroughly wet the wood.
Oxalic acid will brighten the wood in a matter of minutes and does not require rinsing. But your siding does. Rinse off your siding with clean water at very low pressure (about 500 psi) to wash away any stripper or brightener overspray (Photo 4).
If your wood is cedar or redwood, you'll see a dramatic difference as the wood brightens to its fresh sawn color. Our deck is pressure-treated pine, so the brightening of the wood is less noticeable.
Inspect the whole deck
With the deck clean, it's easy to spot any
areas that need additional maintenance.
Drive any nail heads that are popping up
until they're flush with the deck boards.
Look for missing or loose screws, and
replace them with corrosion-resistant
screws that are slightly longer than the
original (Photo 5). Replace missing nails
with corrosion-resistant "trim head"
screws, which are screws that have a small
head and resemble a large finish nail.
If lag screws or bolts are loose in the ledger board, rails or posts, tighten them. Inspect the flashing between your deck and house to ensure it's still firmly in place.
Attack stubborn stains
Although the sodium hydroxide in the
deck cleaner will remove most stains and
mold, particularly stubborn ones require
extra attention.
Use a non-chlorine laundry bleach to remove the stain. (This works especially well if the stain is from mold, mildew or algae.) Apply it to the affected area, then scrub with a nylon brush. Rinse the area with water.
For tougher stains, use trisodium phosphate substitute. Mix the TSP substitute with water and apply it to the stain. Let it sit for a minute or two, then scrub with a nylon brush and rinse with water (Photo 6).
To remove deep stains that don't come out with TSP substitute, let the deck dry. These "bleed" stains are often caused by fasteners. Sand the stains out, using 80-grit sandpaper and concentrating only on the affected areas. Some bleeds may be too deep to sand out. Rough or splintered areas may also need sanding. Spot-sand working in the direction of the wood grain until the surface is smooth (Photo 7).
Wear a dust mask, and sand only if the stain bothers you. You don't have to get every stain out. After all, imperfections are part of an outdoor deck.
4. Rinse the siding and
windows with clean
water at low pressure to
remove chemical residue.
Click Image to enlarge.
5. Sink any raised
nails and screws.
Replace loose and missing
fasteners with screws at
least 1/2 in. longer than
the original.
6. Remove mold,
mildew or algae
using non-chlorine bleach.
Scrub the area with a
nylon brush, then rinse
with water. For tougher
stains, repeat the process
with a TSP substitute.
Click Image to enlarge.
7. Drive the heads of
stain-causing fasteners
below the wood surface.
Then sand out the stains
using 80-grit sandpaper.
Also sand rough or splintered
areas.
Apply the finish - finally!
The deck will need a minimum of 48
hours to dry after the cleaning. If it
rains, wait two more days for the wood to
dry. Avoid staining in high heat, high
humidity and in direct sunlight. Perfect
conditions are an overcast day with the
temperature in the 70s and no possibility
of rain.
Start by staining the top rails and working down the balusters and posts (Photo 8). Run the applicator pad down the length of the wood, applying the stain in a steady, uniform manner. Don't go back over areas that are already stained. Unlike paint, stain gets darker with each coat.
If stain drips onto the deck, smooth it with the applicator pad to avoid spotting. Once the railings are complete, stain the deck boards. Load the pad with plenty of stain, yet not so much that it drips. Start by carefully "cutting in" stain along the house. If stain drips onto the siding, promptly wipe it off using a clean cloth and mineral spirits or paint thinner.
Attach a broom handle to the applicator pad. Glide the pad along the length of the deck boards, staining with the grain (Photo 9). Stop only at the end of a board. Otherwise, the overlap where you stopped and started could be noticeable.
Once the deck is finished, apply stain to the stair treads, working your way down the stairs.
Finally, use a paintbrush or spray bottle to work stain into tight areas that the applicator pad couldn't reach, such as lattice and crevices between balusters and the rim joist (Photo 10).
Allow the stain to dry at least 48 hours before walking on it. Feel the deck to make sure the stain is completely dry. Likewise, check the bottom of your shoes before walking back into the house.
Click Image to enlarge.
8. Apply stain to the top
rail, then the balusters
and the posts. Work from
the top down. Stain one
section at a time, using a
foam applicator pad. Brush
out drips as you work.
9. Stain the deck
boards using a foam
applicator pad with an
extension handle. Stain
the full length of two or
three boards at a time,
working with the grain.
10. Spray on the finish
in hard-to-reach
areas or surfaces that are
difficult to cover with a
paintbrush. Use a wide
spray to avoid streaks.
Work stain into crevices
and narrow areas
between balusters and
posts with a paintbrush.
Choosing the best stain
You have two basic stain choices:
oil-based and water-based. Oil
stains are easier to apply, penetrate
the wood grain and require
less work when you reapply them.
However, they only last two to
four years.
Water-based (latex) stains last four to six years, but they'll eventually peel and require more prep work before recoating. Opaque latex stains generally last longer than semitransparent versions.
When possible, test the stain on an inconspicuous section of the decking. We used a cedar color that worked well since the wood was pressure treated and somewhat dark in color. For a darker color, a redwood-colored stain is available, while a honey color is an option for a lighter, natural wood look.
Be careful not to choose a light color stain if your deck was previously covered with a dark stain or is pressure treated (green). The light stain will not cover the dark wood or darker stain, and it will turn gray within a few weeks.
If you want a natural gray or silver deck, use a clear finish. It will protect the deck from mildew and algae, but not from the sun, allowing the deck to start graying in a month or two.
Pressure
washer
safety
To use the pressure washer:
• Wear appropriate safety gear
and clothes. Rubber boots
and gloves will protect your
hands and feet. Safety goggles
will keep the chemicals
from splashing into your
eyes, and a disposable
respirator or dust mask will
filter fumes.
• Keep the exhaust from the
pressure washer at least
3 ft. away from any objects,
including your house.
• Practice spraying the water
until you find an appropriate
power setting.
• Never point the wand at
anything you don't want
to spray.
• Cover electrical outlets.
Buyer's Guide
The following companies offer a full line of
products for cleaning and finishing decks,
including strippers, brighteners and stains.
The products are widely available at home
centers, hardware stores and paint stores.
Each company's Web site features a store
locator to find the company's products.
BEHR: (800) 854-0133, ext. 2. behr.com.
CABOT: (800) 877-8246. cabotstain.com.
FLOOD: (800) 321-3444. flood.com.
WOLMAN: wolman.com.