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Roof and Ceiling
Insulation
Ceiling (and roof) insulation is critical in most buildings and
climates. Even if
insulation involves lifting the roof, it may be a deserving task
and investment.
The benefits are immense.
Ceiling-roof insulation is a crucial piece of any insulation
- something that in some more extreme cases may avoid 50% of the
home's heating and cooling energy losses...
Layers of insulation
In cold climates, the insulation is usually restricted to
ceiling (or attic).
In hot and warm climates ceiling-roof insulation involves, usually, two layers of
insulation:
- roof
insulation (particularly important in hot climates) and...
- ceiling insulation.
Ceilings and attics may also benefit form reflective insulation
in hot climates. See, on this issue:
Reflective
Insulation.
Ceiling Insulation Materials
Most ceilings are insulated with loose cellulose (R-3.5 per
inch, loose fiberglass (R-2.5 per inch), loose rock-wool, or
batts/rolls of fiberglass
(R-3.2 per inch).
For some tips about choosing the right material, see:
Cellulose insulation
Fiberglass and Mineral
Wool insulation
Sprayed foam insulation
Roof Insulation Materials
Roof insulation is based on a
reflective
material (usually a layer of RFL sarking or foil batts) installed under it.
When installing the reflective material, make sure that there is a minimum gap
(of 1 inch / 2,5cm) between
the roof and the RFL. In the case of sarking, just install it
between the battens and the rafters, with its shiny side facing down.
Note:
Reflective insulation is different from reflective roofing
techniques, based on reflective coatings, membranes or high
reflective tiles in order to get cooler roofs... See on this
issue:
Reflective roofs
Reflective roof materials
Ceiling Insulation
If
you are skilled enough, you may install the fiberglass batts
yourself. Just install it over existing insulation,
and take some basic precautions (gloves,
eye protection, dust mask...).
In
the case of polystyrene
boards, you should place it between the joists.
For loose-fill fiberglass, cellulose or rock wool, it's
better to hire a professional to install the material.
In colder climates two layers of bulk insulation may be
installed to improve the performance, one on top of the other.
Types of roof & insulation
Insulation techniques and materials used in the various types of
roofs - tile roofs, metal roofs; pitched roof with flat
ceilings, sloping ceilings, cathedral ceilings, vaulted
ceilings, and flat roofs – are very alike.
Insulation should be installed with enough space to provide
ventilation and necessary air gaps.
Roof Insulation: R-Value
Typically....
- homes in warm-weather climates should have an R-38
Non-SI roof insulation (or R-7 in the SI system)
- homes in cold climates should have a roof insulation
around R-49 Non SI (R-9 in the SI System).
To a more precise calculation, take into account:
1 - The R-value (thermal resistance) of the materials used in
the roof and ceiling
2 – The R-value you should use in your climate zone: See:
Insulation levels and
Climate zones
3 – Add the difference between 2 and 1: you should use insulation materials
with a R-value equal to that difference.
For details on R-value calculations, see:
Insulation levels and
Climate zones
Insulation performance R-value
Roof ventilation and insulation
in cold climates and humid climates
Roofs need insulation,
but in many cases they also need ventilation, to allow heat/moisture
dissipation. This is a particularly important element in hot-dry climates
and also in colder climates, where a certain amount of
ventilation is necessary to avoid moisture.
In this cases, insulation shouldn't damage the ventilation
system.
Obviously, insulation shouldn't also damage eventual ventilation
systems in other climates, if they exist (in humid climates,
ventilation is usually very limited or inexistent, or demand
drainage mechanisms: ventilation may become a problem in
tropical climates and humid cold climates since it may cause excessive
condensation under the roof).
See:
Insulation benefits
Insulation
materials
Fiberglass, mineral wool &
Home insulation
Reflective roofs
Reflective roof materials
Reflective
Insulation
Insulation
performance
Walls Insulation
Attic insulation
Ducts insulation
Pipe insulation
Moisture and
insulation
How to deal with
Insulation contractors and home builders
Insulation in
your climate zone
Insulation tips
Back to Roof and Ceiling insulation
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