Q:
You've told us how to maintain our wooden decks, now please help those of us
with brick patios. My uncovered brick patio is on the north side of a house
built in the early 1930s. Although the slope of the patio is adequate for good
drainage, the rain and fog and lack of sunlight mean that the brick is damp and
shady much of the winter so that moss grows on many bricks.
Can you
suggest a maintenance procedure to kill the moss or at least inhibit its
growth?
A: Most
often we recommend using a pressure washer to clean decks, patios and house
siding. A pressure washer (either electric or gasoline-powered) converts water
from your garden hose into a pressurized jet. The water may be adjusted from a
pencil-like stream to a fanlike spray. Cleaning solvents can be mixed with the
water to help with particularly tough jobs.
By far the
best way to clean siding, clean a wooden deck or control moss on a brick patio
is to blow the dirt and moss away with a pressure washer. Pressure washers may
be purchased at all the large home centers for $1,500 to $2,500, depending on
the model and pressure they generate.
For
general household use, we'd recommend that you use a pressure washer capable of
generating at least 1,500 pounds per square inch (psi) of pressure. Pressure
washers are also available to rent at your local rental center. The cost is
usually broken into two-hour, four-hour, daily and weekly rates.
Recently,
our brother Bryan repainted Bill's house in Boise. To prepare the exterior
walls, he rented a pressure washer for four hours for $40.
Whether
you decide to buy or rent a pressure washer will depend on how often you use
it. A rule of thumb we use to determine whether to purchase or rent a tool is
if the rental cost will equal the purchase price over a two-year period, we'd
buy rather than rent.
Follow
this procedure in cleaning your brick patio with a pressure washer. Start at an
inconspicuous place on your patio. Hold the wand of the pressure washer a
minimum of 10 to 12 inches away from the surface of the patio to prevent damage
to the mortar joints.
Clean a
small area at a lower pressure and a wide fan spray pattern. If you are not
satisfied with the results, gradually increase the pressure and/or decrease the
fan spray pattern until the surface cleans easily. Do not use any more pressure
or any narrower fan pattern than is required to do the job. Be careful of the
mortar joints. They are old and can be easily dislodged by a high-pressure
stream of water.
If the
patio is extremely dirty, and it sounds like yours is, use a commercial
cleaning additive. These additives are available at home centers. Tell the
salesperson what you are cleaning and they can recommend the proper cleaning
agent.
After you
do the initial cleaning, you may be able to get by without pressure washing for
maintenance. Purchase a nozzle for your garden hose that will produce a narrow
stream of water. Depending on the water pressure at your home you may be able
to clean up the patio on a regular basis without going to the expense of either
buying or renting a pressure washer.
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