Save time on paint prep
A pressure washer is one of the best time-saving
tools to come along in years.
Its high-velocity water spray cleans dirt,
grime and chalking paint from otherwise
sound painted surfaces. Pros like pressure
washers not only because they're fast, but
because they scour the old paint so the new
coat will adhere better. It definitely beats the
old garden hose, scrub brush and TSP cleaning
method, a task so slow that many people just skip it.
In this story, we'll show you how to
pressure wash your home effectively and
safely, from start to finish, without ruining
the siding or compromising the
future paint job. If you're lucky and your
paint is sound (no peeling), pressure
washing may be the only prep work
Should you pressure wash?
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Photo 1: Check for chalking
Rub your hand
over the painted
surface and look for
a powdery light-colored
sure sign of chalking.
will scour it off to
ensure a good
for the new coat.
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Photo 2: Repair before washing
Replace rotten boards and renail loose ones
before pressure washing, so you don't drive
water through the siding and into the wall.
A pressure washer excels at scouring
away dirt, grime and especially chalking,
the powdery pigment left on the surface
when old oil and some latex paints deteriorate.
The scouring action is so strong
that you won't need a cleanser (TSP or
non-phosphate substitute) like you
would if you washed the surface by hand.
First off, look for dirt, especially up
under the soffits. And then rub the paint
surface to check for chalking (Photo 1).
If the previous coating was 100-percent
acrylic latex paint, it probably won't
chalk. If the painted surface is clean and
not chalking, pressure washing is
optional. But most pros do it anyway to
make sure the new paint will adhere well.
The high-pressure stream of water
will blast away loose paint too, but resist
the temptation to use it as a paint
removal tool. The high pressure can easily
gouge wood siding or knock the
mortar from between bricks. Besides,
the pressure washer can't do a complete
scraping job. You'll have to scrape off
additional paint anyway, so you won't
save much time.
Pressure washing works on wood,
vinyl, aluminum siding and masonry,
but due to its high pressure, we
don't recommend it for
hardboard siding. Hardboard
is more vulnerable
to moisture than wood and
it's extremely difficult to
repair if you accidentally
Pressure washing won't
stop mildew. (It'll wash most
of it away, but the mildew will
soon grow back.) Mildew
resembles a dirty-looking
blackened area. To identify it,
apply a little bleach. If the black
spots disappear, you have
mildew. Using a scrub brush
instead of the pressure washer,
wash the area with a mixture of
1 part bleach to 9 parts water. If the
bleach test had no effect on the
black spots, they're dirt and you can
pressure wash them away.
Warning: Pressure washing is not a safe
paint prep method if the exterior paint
contains lead. If your home was built
before 1978 (when lead paint for residential
housing was banned) or if you're
unsure, have your paint tested or contact
your local health department for safe
Time and money
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Photo 3: Hook up the pressure washer
Connect the pressure
washer to the
outdoor faucet through
an ordinary garden hose,
attach a nozzle (see
“Selecting the Best Nozzle,” below) and start the
engine. Wear goggles to
keep paint chips and dirt
out of your eyes, and
clothing that can get
soaked. You WILL get
wet. Spread old sheets
or painter's cloths on
the ground and over
shrubbery to catch
Rent a washer that produces
at least 2,000 psi
(pounds per square
inch) of pressure. It'll
cost about $70 to $100 per
day, and expect to
keep it for a full
day. You don't
have to be experienced
to use one, but be
prepared for a day of physical
labor. The washer will probably be gas-powered
and weigh more than 75 lbs.
Depending on its size, you might need a
pickup or van to haul it and
help to unload it. Ask the rental agent to
show you how to hook it up
and operate it, and to
review safety precautions
Pressure washers look
like the ultimate squirt gun,
but they aren't toys. Don't
point them at anyone or try
to rinse your hands or feet.
They can tear your skin
right off. If you don't
feel confident operating
it, hire a pro.
sure you get a
6- to 12-ft. extension
wand to help
reach high areas
Selecting the Best Nozzle
Pressure washers usually have three or
four nozzles with spray patterns of
varying widths. Attach the 15- or 25-
degree nozzle to the wand for general
paint cleaning, then test the effect on
the siding (Photo 6). The spray should
clean away all dirt and chalk without
damaging the siding. Rub the surface
with a clean glove to make sure the
chalk comes off. If it doesn't, try a nozzle
with a narrower pattern. Don't use
the narrow, zero-degree nozzle. It's
powerful and can quickly damage
wood, stucco and other
materials (Photo 7). Also make
sure the nozzle
coupling locks into
place securely so you
don't blow the nozzle
through a neighbor's
Pressure washing techniques
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Photo 4: Practice first
the washer in a low
area first. Hold the wand
with two hands and move
it across the siding from
side to side at a steady
pace. Start about 2 ft. from
the siding, then move
closer until you find the
optimal cleaning distance.
In general, work at a horizontal
or slightly downward
angle to avoid driving
water up under the siding.
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Photo 5: Work from the top down
Begin washing the walls
at the top and work down.
Wash the gutters and soffits as
well as the siding. Direct the
spray away from breakable
objects like windows and outside
lights, and remove house
numbers and window boxes
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Photo 6: Scrape after washing
Pressure washers will
remove loose paint,
but they're not a
substitute for scraping.
We'll have to
loose paint after
this area anyway.
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Photo 7: Oops!
If you hold the
nozzle too close or for too
long in one spot, you'll gouge the
wood. We'll have to fill this area
with wood putty before repainting.
Gouging is inevitable if you try to
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Photo 8: Point away from windows
Direct the nozzle away from
windows, holding the wand at an
angle so you don't drive water into
joints, gaps or against the glass. Even
so, check the sill on the inside and dry
up any water that leaked through.
Remove the shutters after washing
and wash underneath.
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Photo 9: Use an extension wand
Use an adjustable
(6 to 12 ft.) to wash
high areas. At full
length, the wand takes
some muscle to handle.
Good control takes
some practice, but it's
safer than pressure washing
from a ladder.
Remember to close all
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Photo 10: Scrub inaccessible areas
Clean high areas beyond the reach of the pressure washer
extension with a scrub brush and a solution of detergent and TSP
mixed in water. Begin from the lower areas and work upward, rinsing
frequently. Keep the siding below damp so the TSP won't leave visible
drip marks. When finished, rinse from the top down using a garden hose.
An add-on ladder stabilizer makes the ladder more secure.
Follow the photo series for the pressure-
washing basics. If you haven't
handled the tool before, be sure to
take a few minutes to practice, get a
feel for the wand, and choose the most
effective spray pattern (Photo 4). For
better control and to keep your arms
from tiring, use two hands.
- While it's best to wash with the
wand aimed downward, at times
you'll have to point it somewhat
upward, especially under soffits
(Photos 5 and 9). When you do,
remember the general rule not to
drive the water directly into cracks
or gaps. And always avoid shooting
water up into soffit vents.
- We don't recommend that you
pressure-wash while standing
on a ladder; the recoil from the pressure can knock you off balance.
- Steer clear of electrical devices like
lights and outlets (Photo 5). You can
easily cause a short circuit or break
Warning: Keep the wand and water
stream at least 6 ft. away from electrical
wires (Photo 9). A shock from
your service wires can kill you.
- Stripping loose paint (Photo 6)
and gouging the wood in the
process (Photo 7) is the most
common rookie mistake and will
leave you with time-consuming,
difficult wood repairs.
- Give your house at least a week of
good drying weather before applying