The next time
you take a shower, consider the damage you may be causing to
your home. Actually, one shower won't cause moisture damage in
itself, but together with washing clothes, steam from cooking,
and dishwashing, a good deal of moisture is added to the atmosphere
of your home each day. And on the outside, rain and snow regularly
drop a good deal of moisture on your house. All these factors
can cause extensive damage both to your home's appearance and
structure. Moisture can cause ugly rusting or decay of building
materials, and blistering or peeling of painted surfaces. It
can warp wood, and promote mildew and other fungi growth on our
need not be a menace, if you are aware of its threat and take
the proper steps to prevent its accumulation in unwanted areas
of your home. You should understand how moisture damage occurs,
learn how to prevent future damage, and know how to repair present
Moisture Damage From Outside
Each year rain, ice and snow can expose the outside of your home
to great quantities of moisture. Moisture has historically been
the cause of damage to building structures, but because of recent
energy-saving measures, environmental factors can cause more
havoc to homes than they used to.
methods and building standards have changed to accommodate the
increased interest in conserving energy. Houses built prior to
the 1930s generally had no effective insulation in either ceilings
or walls. Roofs were usually steeply pitched and constructed
with shingles that had gaps between them which ventilated attics
and cooled the roof deck.
These homes were,
of course, heat-wasters -- heat escaped into the attics and natural
ventilation kept the attic air moving. As a result, roof-snow
melted rapidly and did not accumulate. Ice and icicles formed
on the eaves and in the gutters rather than remaining on the
roofs. Snow-water penetrations into the house were insignificant
and gone before they could cause damage.
But in these
days of high fuel costs and the need for energy conservation,
new houses and modernized older homes must meet new standards.
Often, the new standards represent only minimum requirements
and serious moisture damage results.
Because of increased
insulation, millions of homes now have warm attics instead of
the hot attics in the old heat waster houses. The snow accumulation
on roofs of houses with warm attics melts slowly along roof edges
causing water pools to back up behind ice dams.
The water often
remains in this area for weeks, penetrating roof shingles and
finding its way into ceilings and wall cavities. This, of course,
can create severe damage, such as soaked insulation, stained,
swollen and cracked plaster and drywall panels, dampness and
rotting in wall cativities and, eventually, stained, blistered
and peeling paint. Interior paint damage may show up fairly soon.
The blistering and peeling of exterior painted surfaces, however,
may not become apparent until summer weather arrives. Water trapped
in insulation and wall cavities may then penetrate the wood siding
and emerge as blisters under the exterior paint film.
Rooftop ice dams
aren't the only exterior moisture culprits. Water from moisture-soaked
ground can seep into a home's basement through the foundation.
Once water has penetrated into the home, it may continue to do
so whenever a heavy rainfall occurs. Obviously the water will
eventually cause damage to interior and exterior building materials.
Exterior Prevention Measures
There is little point in repairing damage done to the structure
of your home unless you first take all the necessary steps to
prevent future moisture problems. You should first eliminate
the cause of problems before tackling the result of them.
inspect your home for clues of moisture damage.
The first days
of spring are a good time to check these spots:
- Near gutters
and downspouts, windows and doors, and the ground level row of
boards or masonry.
- Old caulking
materials, where gaps may have occurred.
- Masonry and
roofing where hotels or seams may have appeared.
- Gutters and
downspouts where there may be backups or leaks.
Once you have
sized up the damage, follow these steps to overcome future problems:
- To prevent future
damage from ice dams, remove snow from the roof, wherever possible.
- Electric heating
cables are available to melt ice in gutters- but be sure to melt
and clear downspouts first.
- The best safeguard
is a well-insulated, but well-ventilated attic.
- If the attic
can be kept near the outside temperature, ice dams aren't likely
- Remember, proper
insulation must be done in conjunction with adequate ventilation.
- Repair any damage
to your roof as soon as possible and apply a roof coating if
- Clear dirt and
debris out of gutters and downspouts and repair them with a patching
compound and a coat of the proper paint.
- Make sure that
flashing under shingles is secure, does not leak and covers proper
- Caulk around
problem areas such as wall joints or cracks, pipes through walls,
window and door frames, flashing, leaky gutters and downspouts.
- Keep heavily
used decks and porches in good repair, recoating or repainting
every two or three years.
- Trim shrubbery
away from buildings to allow air circulation in ground-level
Once you are sure the moisture has been dried out of the wall
cavities and an adequate ventilation system has been installed,
you should begin repairing exterior paint damage. Where the paint
is blistered, loose, or peeling, it will have to be removed.
Paint damage caused by moisture usually results in the paint
coming loose right down to the bare wood.
All exposed wood
surfaces should be sanded and spot primed with a suitable exterior
primer. Many paint manufacturers recommend a solvent-thinned
alkyd type for this purpose. When the primer is dry, apply a
topcoat of either an alkyd or a latex exterior paint following
label directions carefully. Your paint retailer can help you
choose a paint that's right for your home.
Trapped water and moisture, escaping toward an area of less vapor
pressure is technically the cause for moisture damage. When excessive
moisture is retained in such areas as ceilings and walls that
are not properly ventilated, it will begin to work its way out
through these surfaces, causing a variety of ills to the materials
with which your home is built.
Inside your home,
you contribute to this build-up of moisture in many ways -- bathing,
cooking, washing, and even breathing. Of course you can't call
a halt to these basic activities. But you can make sure the moisture
they create is routed safely to the outside instead of into your
walls and ceilings.
As with exterior damage, it doesn't help much to repair the surface
of the interior of your home before you have corrected the problems
that caused the damage in the first place. Check for interior
surface damage in such moisture-prone areas as kitchens, bathrooms,
laundry rooms, attics and basements. Be sure to look past cosmetic
damage and check insulation to see if it is wet.
The key to preventing
future moisture problems inside your home is to make sure your
house is tight enough to prevent moisture from entering but at
the same time adequately ventilated to allow interior-produced
moisture to escape. Most importantly, you want moisture to escape
through vents, windows and other openings created for that purpose
- not through walls and ceilings where it will eventually cause
fans or louvers to properly ventilate your home so that moisture
can escape to the outside.
basement from the outside. Make sure the basement contains adequate
drainage to avoid build-up of standing water.
In homes without
basements, rot-proof sub-flooring and joists are necessary, and
the ground under floors should be covered with a vapor barrier
such as polyethylene plastic.
When insulation gets wet, it conducts cold rather than inhibits
it. Insulation should be completely dried out before repairs
If damage to
your walls or ceilings is severe enough to require replacement
of some of the panels, you may need the help of a professional
painting contractor. He can assess the damage and give you an
accurate cost estimate for repair. Many painting contractors
are qualified to do the whole repair and repainting job for you.
To repair sagging drywall on ceilings, it is recommended that
5/8 inch panels be used. The old damaged panels can be removed
and replaced or new drywall can be installed in front of the
sagging panels. The thicker, 5/8 inch drywall is recommended
today, since greater amounts of insulation are being used.
On the outside,
under exterior overhangs, use waterproof sheetrock or exterior
grade plywood panels to replace sagging drywall.
Once the structural
damage has been repaired and you have determined that wall cavities
and areas above ceilings and under floors have been properly
dried out, you should repaint. Ask your paint retailer to help
you choose the correct paint for your particular purpose and
follow manufacturer directions for application.
Most stains caused by water are likely to be amber or brownish
streaks or blotches. If
p laster or gypsum board has not been damaged by water, repainting
may be a sufficient remedy for stains. Since water has caused
the stain, you can assume that it is at least partially water
soluble. Wash the stained surface carefully with water and detergent
or a household cleaner intended for cleaning paint. Without soaking
the surface, remove as much stain as possible. Allow the washed
surface to dry thoroughly - 48 hours or longer.
the finish coat of paint, use a special stain-blocking or stain-killer
type of primer sealer. These primers are solvent-thinned therefore
they will prevent further leaching of the water-soluble staining
material. Any type of topcoat or enamel may then be used.
If painted woodwork,
doors or paneling are discolored or stained by water from inside
walls or ceilings, they can usually be refinished with a moderate
amount of work. If the painted surface is blistered or the paint
is peeling or chipping, it may be necessary to remove the paint
down to the wood surface to achieve a smooth attractive finish.
Many types of paint and varnish removers are available at your
paint dealer. Be sure to follow label directions carefully when
using paint removers.
If the painted
wood surface has not been badly damaged, but has become dulled,
discolored or stained, clean the surface thoroughly, sand lightly
and apply an enamel undercoat. Allow the undercoat to dry completely,
then sand lightly with a very fine sandpaper. Wipe clean and
apply either an alkyd or latex enamel in any color or sheen you
If the wood surface
has not been painted but is a finished natural wood, minor damage
may be repaired with a light sanding, followed by a coat of gloss
or semi-gloss clear varnish. When the damage is extensive, remove
the finish, sand the wood until it is smooth, and refinish. Most
paint stores carry a wide variety of fine wood stains as well
as clear varnishes in a choice of sheens.
If water has caused plaster to swell and crumble, or if sections
have collapsed, it is likely that new plaster will be needed
in some areas. New plaster must be allowed to dry and harden
properly before painting.
contractors often use a moisture meter to determine whether an
area of plaster is dry, wet or very wet. But if you are doing
your own work and cannot readily purchase or rent a moisture
meter, be sure to allow adequate time for the plaster to dry.
Most plaster can be safely painted in four weeks, if the temperature
in the house or building is above 50 degrees F. and the relative
humidity is not above 70 percent. If your home does not meet
these conditions, or if plaster is applied directly to a solid
wall such as brick, tile, etc., a longer drying time is necessary
If you must paint
new plaster before adequate drying time has elapsed, the best
procedure is to apply just one coat of a high quality latex wall
paint. The latex paint will not be affected by any free alkali
coming to the surface and the single coat will allow moisture
to continue to evaporate through the paint without causing blisters.
Later, another coat or two of either latex or alkyd wall paint
may be applied.
Once you have
determined that your newly plastered walls are dry enough to
paint, you should check them carefully for chalky areas.
These can occur
when plaster dries too rapidly at high temperatures. Chalk should
be removed by vigorous brushing before painting.
Drywall which has become badly soaked by water from inside the
wall will probably need replacement. Once new gypsum board panels
have been installed and the joints have been properly taped and
sanded, painting is a fairly straightforward procedure.
For the first
coat on new gypsum board, a latex primer is recommended. These
fast-drying, water-thinned primers prepare the drywall panels
for topcoat painting by providing a smooth, sealed surface. Following
an evenly applied coat of latex primer, the topcoats can be either
latex or alkyd paint in your choice of color and sheen. Latex
wall and ceiling paints are usually recommended for this purpose
because they clean up easily.
Certain types of paint can be excellent vapor barriers - helping
to keep moisture from permeating walls and ceilings. Vapor barriers,
when used to coat interior ceilings and walls, inhibit inside
moisture from penetrating these surfaces and damaging insulation
and exterior finishes. Many of the familiar paint products work
well as moisture barriers and there are now special vapor barrier
paints available as well. A topcoat can be applied over the vapor
barrier paint if the latter is not available in the color of
By ridding your
home of moisture traps, promptly repairing any damage, and repainting
or recoating properly, your home will be more energy efficient,
protected from harsh weather, and more attractive.
© National Paint & Coatings Association