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House missing its vinyl siding
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Below you will find check lists that require you to know the kind of wall
structure (or structures) used in your house. One kind is frame construction
(houses whose structural walls are made of wood studs) and the other is block
construction (houses whose structure is made of concrete blocks). Don't
judge based on what you see as the outside skin. Instead determine by
what you know or how thick the walls are. Frame houses have outside walls
that are about 5" to 7" thick whereas block houses have walls that are closer
to 10" thick. Bear in mind that a house may have both kinds of construction.
Entry walls or front walls may be wood frame while the rest of the house is
concrete block. There may be wood frame sections where doors or windows were
filled in or where a carport or garage was converted to living space. Answer
the questions for both frame and block if your house has both.
Inspecting your house:
Frame house with boards running horizontally, vertically, or diagonally:
Frame houses with board siding may have been built with a water resistive barrier
applied to the studs and then boards fastened to the studs through the barrier.
This may result in a fairly effective system at keeping interior walls from
becoming saturated as long as any water that accumulates in droplet form has
a direct passage out of the house. In other houses plywood may have been
applied directly to studs, then a water resistive barrier, and finally boards.
Because boards can become saturated with wind driven water and because water
resistive barriers may then become saturated the plywood in contact with the
barrier can also become saturated.
The direction siding is run makes a difference in how much risk there is
that water will get past the boards towards the interior. Horizontal boards
can be pretty effective whereas boards run vertically or diagonally sometimes result
in water being routed towards the interior of the house. Once the boards are
in place you can't do much other than to take precautions. However, if
you see places at the lower ends of boards that are apt to dump water behind
the boards you may be able to fill those gaps with caulk in an aesthetically pleasing
or hidden way. If you do this you definitely need to check before the next
hurricane that the caulk has withstood expansion and contraction between seasons
and between humidity conditions.
Filling holes and cracks with caulks and good layers of paint over the walls
can reduce the chance of water saturating plywood. They won't prevent water
from getting driven in through cracks between boards but may substantially reduce
the amount of water intrusion.
Frame houses with vinyl or metal siding: Frame walls with vinyl
or metal siding are similar to those with horizontal board siding except that
these siding materials may be more apt to let wind driven rain get behind them
than wood planks.
Frame houses with stucco: Some frame houses with stucco finishes
do not have plywood or similar sheathing applied to the studs. Some do.
The key issue is whether there is a way for water that will get absorbed by
the stucco to fall to the ground behind the wall before it gets absorbed into
the water resistive barrier. This will depend on the knowledge of the person
who did the installation. The latest research shows that a single layer of
water resistive membrane is not always adequate to keep water from saturating a
wall whereas two layers properly installed provides a drainage path that will
render most of the water harmless. Because it is difficult for most people
to determine whether stucco was applied properly, it is especially important to
assume the worst by ensuring that the surface of the stucco allows little passage
of water. See the discussion below about porous surfaces.
Frame houses with brick or stone: Frame houses with brick or
stone most likely have a wall sheathing (plywood, OSB, or other sheathing
(thermoply) in place) that should have a water resistive barrier applied to
it. It is likely that the water barrier is not completely effective and
it is likely that mortar has formed a dam that will allow moisture to accumulate
and soak the sheathing.
Block, raw with just paint: Enough layers of paint (or more
accurately said, a thick enough coat of paint) can be pretty effective as
a water barrier. It is likely that a house with raw block walls and paint
is an older house that may well have received several layers of paint over
the years. If you add another coat of paint, be sure to caulk any cracks before
painting.
Block with thin a layer of cementitious material: Cementitious materials
may be a very thin layer of concrete (stucco material) applied by hand with
a trowel or a similar material applied by a sprayer. These finishing materials
do help fill the holes in concrete block, but most often they are so thin
that they are not very effective in providing a water barrier. Even when
painted these finishes do not provide a really good barrier. However,
multiple layers of paint have been found to be much more effective than no paint.
Block with brick or stone facade: Brick is very, very porous.
In just minutes a brick can absorb a lot of water when put into a pail
of water. Wind driven rain is even more effective at causing brick to absorb
water. Brick walls are supposed to be constructed with an air space between
the brick and the block. However, it is a common installation problem that
the space gets filled up during the brick laying process with mortar debris.
This debris can cause water that gets absorbed by the brick to become trapped
between the brick and the interior face of the house. Cracks that inevitably develop
in brick and stone walls also contribute to the amount of water absorbed by
the wall.
Block with wood, vinyl, or metal siding: If your house has
wood, vinyl, or metal siding that has been applied to fur strips, then you
probably have a pretty good barrier against water. However, wind driven rain
can get past the siding. For this reason you want to be sure that the larger
openings in these sidings are well sealed against water.
Porous surfaces: Porous surfaces include practically every building
material except vinyl or metal siding. Brick, concrete, stucco, and wood
clearly are porous surfaces that can become saturated with water if subjected to
wind driven rain for a long enough time. For surfaces that are porous the
two principal ways to keep them from becoming saturated are to have them thick
enough and to have a surface coating applied like paint that resists water.
Paint can slow down water penetration, but it does not stop it.
Dealing With Porous Surfaces With Paint:
Almost no surface applied to a house is waterproof. Contrary to what many
think neither concrete nor paint are waterproof. They are water permeable;
but, they do not allow water to pass quickly. One might suppose concrete to
be waterproof after all swimming pools are made of concrete. However swimming
pools have a very dense surface coat (commonly known as marcite) applied to
the concrete to help keep water from the concrete shell. Some paints are
more effective at keeping water out than others; however, in practical applications
these paints are perhaps not best suited for houses. What does help is
having enough paint thickness on stucco or boards. Houses that have only
been painted once or twice do not provide as much water protection as houses
with more coats.
Frame Houses:
If your frame house has an effective water resistive barrier it may be able
to tolerate water getting behind the outer surface. Two criteria have to
be met. One is that the material actually is impermeable to water droplets under
pressure, that it is applied in a shingle fashion so that water continuously flows
away from the interior, and that water has a way to flow out harmlessly to
the ground. It is very difficult to determine all these criteria without removing
the skin.
Houses with board siding
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Knots. Knots are missing resulting in knot holes through which one sees the bare house.
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Is there a vapor barrier between the plywood of the house and the vinyl or metal siding? Such sidings do not pretend to be a water proof surface in high wind conditions unless it is supplemented by a properly installed vapor resistive barrier system.
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Houses with stucco or cementitious coverings
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Are there stair step cracks following some block lines where the width of the cracks are such that if the crack was smooth you could insert a piece of paper?
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Are there hairline cracks in the stucco or cementitious finish? Include very, very thin cracks.
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When you look at the house after a rain and it is drying out you can see multiple lines that upon closer examination show to be hairline cracks? This indicates that water has gotten into those cracks and has not yet dried out.
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Are there places where stucco has been repaired? If so look very, very carefully for cracks. It is most likely that such repairs were not done properly because it takes a thorough knowledge of stucco installation standards, is not easy, and it takes diligence.
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For repairing hairline cracks caulk is a good material to use. Because the
cracks are so small caulk will inevitably get smeared outside the crack and
thus be unsightly if the wall is not painted. In fact two coats of paint may
be necessary in areas to mask the difference in texture caused by the application
of caulk.
Stair step cracks or other larger cracks can be filled with caulk as just
described. If holes are too big to be filled with caulk, then consider using
a plastic type stucco repair material such as StuccoFlex.
Inside wall coverings can affect mold:
As discussed to elsewhere, walls that get wet need to dry. They can potentially dry
to both the outside and inside. If interior walls have water impermeable coverings
such as tile, vinyl or aluminized wallpaper, or are painted with enamel paint
they will not readily dry through that material. Walls need to dry out quickly
(within a day or two) to prevent mold. So when refinishing interior walls
avoid using impermeable materials.
Paint considerations:
Acrylic latex paints are probably the best for wood and cement. Clear stains
do not protect wood from damage caused by ultraviolet light and typically do
not offer much water protection. Rigid coatings like urethanes and enamels tend
to crack as wood changes width with humidity. Cracks in these coating open
the wood to water while limiting the surface area for drying. Elastomeric paints
are generally not recommended because in spite of their generic name they
are not very elastic and unless they are installed perfectly they can bubble
and trap water. They may well make sense in some commercial applications,
but are regarded as a poor choice for residential applications. If you have
any questions about paint, seek advice from knowledge paint store personnel.
When painting walls one may find that one can paint just the affected walls
corner to corner without having to paint the whole house. Because light angles
change at corners of houses and at corners of rooms, one can have a fair change
in paint shade without it being immediately apparent or objectionable.
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