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[ Selecting Insulation
]
[ Types of Insulation ]
[ Installation and Safety Tips ]
When selecting the type of insulation best suited to your needs remember
that, while each of the different types has a varying physical look and
size, you can compare the insulating abilities by comparing the R value.
The R value is a measure of resistance to heat flow - the higher the R value
the greater the resistance and the better the product is at insulating.
Products with the same R value will provide the same level of insulation.
For bulk insulation, R values are related to thickness, density and nature
of the insulating material. Increasing the depth of the bulk insulation
will increase its R value. However, covering the ceiling joists can create
a safety hazard by obscuring safe footing positions.
Reflective insulation does not have insulation properties by itself. Instead
the insulation value depends on the particular installation details, including
the presence of still air gaps next to the shiny surfaces, as well as the
properties of the reflective material itself.
Reflective insulation has different R values depending on how it is installed
and can have different R values in summer and winter (with the winter R
value being less). Settled dust will reduce the effectiveness of reflective
insulation products where the dust covers any upward facing shiny surfaces.
It is important to ensure that the R value used for reflective insulation
is the correct one for the particular circumstances in which it is to be
used, with allowances made for dust settling on surfaces over time.
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Recommended levels
The level of insulation required for your home depends upon two
things: the climate and the type of construction used. The map (left)
gives a general indication of the climate zones that dictate the level
of ceiling, wall and under the floor insulation required. Using the
map, determine which zone your house is in.
Then select the 'Easy Guide to Insulation' attachment for your zone
and select the type of construction used for your house. The guide
will give you the level of ceiling and wall insulation required for
a house that is built on a concrete slab on the ground in your zone.
For other types of floor construction, refer to the Building Code
of Australia (BCA). Also refer to the BCA for insulation requirements
for reflective foil laminates and combination foil and bulk insulation.
Insulation in new homes and renovations must adhere to the requirements
of the BCA. For example, in Perth, under the BCA, insulation is not
necessary in the cavity masonry walls. However brick veneer and framed
walls do require insulation. The Easy
Guide to Insulation (PDF 224 KB) may be used to select
insulation levels for existing houses, however, retrofitting insulation
in existing walls and in some ceilings may be difficult.
How thick (in mm) does the insulation have to be?
| Common bulk insulation materials |
R1.0
|
R1.5
|
R2.0
|
R2.5
|
R3.0
|
R3.5
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| Cellulose fibre loose fill |
40
|
60
|
80
|
100
|
120
|
140
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| Glass fibre batt |
44
|
66
|
88
|
110
|
132
|
154
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| Polyester or wool blanket |
45
|
68
|
90
|
113
|
135
|
158
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| Polystyrene expanded |
39
|
59
|
78
|
98
|
117
|
137
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| Polystyrene extruded |
28
|
42
|
56
|
70
|
84
|
98
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| Rockwool batt |
28
|
42
|
56
|
83
|
99
|
116
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| Wool (80%) Polyester (20%) batt |
45
|
68
|
90
|
113
|
135
|
158
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These values are indicative only. R - value is reduced if the material
is compressed to a lesser thickness that affects the density. Refer
to manufacturer's catalogue for values at various densities. |
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