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Helps to prevent the transfer of heat either into
or out of a building
Winter – keep heat in
Summer – keep heat out
Heat is transferred through walls, floors,
ceilings, windows, and doors at a rate related
to:
Difference in temperature
Resistance to heat flow provided by
intervening materials
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Done after exterior of house is completed and
house is water proof
After rough plumbing system is installed
After rough electrical system is installed
After rough HVAC system is installed
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Three methods – conduction, convection,
radiation
Conduction – transmission of heat from one
molecule to another within a material, OR;
From one material to another when they are
held in direct contact.
Dense materials such as metal or stone conduct
heat more rapidly than porous materials such
as wood and fiberglass.
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Convection – transfer of heat by another agent,
such as air or water.
In large areas molecules of air can carry heat
from warm surfaces to cold surfaces.
When air is heated it becomes lighter and rises.
Air is a good insulator when confined to
smaller spaces
Or porous materials and their cells help confine
heat
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Heat is transmitted by wave motion in the
same manner as light.
Radiant waves do not heat the space through
which they move.
But when they contact colder surfaces the
energy is absorbed.
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Great insulators include:
Air – already mentioned
Fibrous materials because of the porosity of the
fibers
Also because of the thin film of air that
surrounds each individual fiber
Good insulation material should be fireproof,
vermin proof, moisture proof.
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Loose Fill – Sprayed or poured into cavities
that require insulation.
Rigid Insulation – usually used for roof and
wall sheathing, subflooring, interior surfaces,
base for plaster and synthetic stucco exterior
wall finish.
Reflective – usually a metal foil.
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Flexible – blanket, quilt, or batt.
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Blanket insulation is enclosed with paper tabs on the
sides for attachment.
Made of fiber glass or fiber-like materials
Paper also serves as a vapor barrier.
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Heated areas especially in cold climates.
Walls, ceilings, and floors, crawl spaces,
finished attic, finished basements.
Best to have insulation as close to heated area.
For example the ceiling joists should be
insulated if the attic is unused. If the attic is
used, ceiling joists and rafters should be
insulated.
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Insulation and other building materials have an
R-Value.
(R) represents resistance, which is the opposite
of conductivity or conductance.
The higher the R-Value the better the
insulation.
2x4 insulation has an R-Value of 13.
2x6 insulation has an R-Value of 19.
Thicker the insulation the better the R-Value.
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Water vapor is always present in air.
Acts like a gas and penetrates wood, stone,
concrete.
Water vapor creates condensation.
When warm air is cooled, some of its moisture
will be released as condensation.
Condensation reduces the R-value of
insulation.
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Vapor Barrier – Membrane through which
water vapor can not readily pass.
Vapor barrier must be installed on the warm
side of the insulation (heated side).
Prevents moisture from moving through the
insulation to the cool side where it could
condense.
If insulation roll does not have a vapor barrier,
use polyethylene films or rolls.
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Always wear safety glasses, and vapor mask if
applicable.
Don’t rub or scratch your eyes or skin.
Wash hands with cool water and soap. Do not
wash with hot water.
Wear loose fitting clothes with long sleeves.
Wear gloves if provided.
Do not play with insulation. No horseplay with
insulation.