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Insulation & Moisture
We need humidity in the air we breathe, but too much
moisture is a cause of damages in the building materials and a
source of health problems.
Uncontrolled moisture can lead to mold growth
that impairs indoor air quality.
When moist air comes in contact with cold surfaces, part of the
air vapour condenses, which may happen inside a wall or in
attics, away of our seeing, causing the problems.
Assuring
the integrity of exterior walls through insulation is the first
line of defense for preventing moisture. But a
correct insulation of interior walls, basements, attics, roof
and ceiling are also essential means for keeping moisture
away.
Right insulation materials to prevent moisture problems
You should ponder the best materials to prevent moisture. Good water resistant wall paint is a very effective and easy
way of preventing moisture and a first insulation barrier. But
there are other more specific materials, namely:
- polythene sheets
- reflective foils
- foil backed plasterboards
- polystyrene (see:
Spray-on foam insulation)
Materials with a vapor-barrier membrane are particularly suited
for the more exigent cases of insulation: the membrane
decreases the possibility of moisture vapour condensing to water
within walls, attics or other structures.
Common examples
is asphalt impregnated paper or metal foil.
Vapor
barriers
Vapor
barriers are available as part of many insulation products,
and are a crucial way of keeping moisture out of buildings.
Floors, framed
walls or roofs should have vapor barriers on the warm, moist
side of the insulation.
For floor slabs contacting with the ground, you should consider
installing a 3-6 mil continuous vapor barrier under the slab.
It's essential to prevent moisture entry through it.
Correctly installing a vapor barrier
Use vapour barriers to protect materials from condensation
wherever needed: in places with low ventilation, on underside of
metal roofs.
Vapor barriers are specially important in
lockers, showers
and other areas of the house where
the humidity levels are usually high.
Also tape or glue joints in vapour barriers, and
during
construction ensure that vapor barriers are continuous, not
damaged and tightly secured.
Other ways of controlling moisture
Insulation is
important, but the design and proper installation of roof
flashing, windows, doors and other areas where moisture can
easily enter the building are also crucial.
Also crucial are drainage measures linked to the house:
adequate sloped roofs, sloped intake plenum, adequate ground
slope around the building, sufficient overhang in exterior
entries, well cleared and opened gutters and downspouts, etc.
Another major way of fighting
moisture is ventilation.
An adequate ventilation of spaces where moisture can build up is
fundamental, and there are building codes requiring ventilation
of crawl spaces, attics and vaulted ceilings.
But ventilation should also be managed carefully, because it can
also be a cause of condensation and… moisture in our houses.
Excessive ventilation in humid (cold or tropical climates) is
a cause of undesired moisture.
See for more information:
Natural ventilation
ERV and
HRV ventilation
See also:
R-value: Insulation
performance
Insulation benefits
Insulation
materials
Insulation
performance
Roof Insulation
Walls Insulation
Ducts insulation
Pipe insulation
How to deal with
Insulation contractors and home builders
Insulation tips
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