Title Design Guide - Building 1.2 MB 48
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R e s i d e n t i a l & C o m m e r c i a l

BUILDING

D E S I G N G U I D E

B
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24 C S R B R A D F O R D I N S U L A T I O N

Thermal and
Condensation Control.

Example 1:

A proposed factory building is to have a low
pitched metal deck roof insulation with 55mm
Rockwool building blanket with a vapour barrier of
aluminium foil laminate on the underside. All
components are to be in close contact. Calculate the
thermal resistance and transmittance of the proposed
system for winter conditions.

The individual resistances are summed as follows:

Outside air surface, Rso : 0.03

Metal Deck : Negligible

Glasswool blanket : 1.30

Inside air surface (reflective, Rsi) : 0.20

Total Resistance, R : 1.53m2 K/W

Transmittance, U = : 0.65 W/m2K

Example 2:

Determine whether condensation will occur in the
assembly of Example 1, assuming winter conditions
with an outside air temperature of 0°C and an inside
atmosphere of 20°C temperature and relative humidity
up to 90%.

Heat flow:

Q = U(tl - to)

= 0.65 (20 - 0)

= 13.0 W/m2

The rate of heat flow is the same through all
resistances. Therefore:

Q =

Where th is the temperature on the warm (internal)
side, and Rsi is the inside surface resistance.

ie. =

from which th = 17.4°C

Referring now to Table 9, air at 20°C and 90%
R.H. has a dew point of 18.3°C.

20 - th
0.20

tl - th
Rsi

1
R

Therefore, there is some r isk of condensation
occurring under these conditions and the thickness of
the insulation blanket should be increased to 75mm as
a safeguard. This will increase the thermal resistance of
the insulation to 1.8m2K/W.

The new values for total resistance and
transmittance now become:

R = 2.03m2K/W

U = 0.49W/m2K

Recalculating the heat flow and inside surface
temperatures as before gives:

Q = 9.8W/m2K

th = 18.0°C

This is the above dew point for the worst
anticipated inside atmosphere conditions and
condensation should not occur.

Example 3:

The walls of a proposed air conditioned process
building are to achieve a U value less than 0.6W/m2K
(summer conditions). The outside wall cladding and
internal wall lining will both be metal. What thickness
Rockwool blanket will be necessary to achieve the
desired U value, assuming one airspace in the assembly?

The minimal total Resistance required,

R =

= 1.67m2K/W

The sum of resistances without insulation are:

Outside surface, R0 : 0.04

Air space : 0.15

Metal lining : Negligible

Inside surface, Rj : 0.12

Overall Resistance
without insulation : 0.31m2K/W

Therefore the minimum resistance required from
the batt insulation = 1.36m2K/W.

The thermal resistance of an R1.5 Bradford
Fibertex Rockwool or R1.5 Bradford Glasswool
blanket is 1.5m2K/W.

Thus an R1.5 value blanket will be necessary to
achieve a U value of 0.6 W/m2K.

1
0.6

Design Calculations.

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These samples are supplied to assist you in
preparing your project specifications. Select or insert
the required data where words are shown in italic font
to prepare appropriate specifications.

APPLICATIONS DETAILED.
• Metal Deck Roof.
• External Walls - Commercial and Industrial Buildings.
• Internal Partitions – Framed Construction.
• Suspended Concrete Slab.
• Commercial Ceiling.
• Curtain Walls
• Party Wall Fire Protection.
• Timber Floor and Floor/Ceiling Systems.
• External Wall (Brick Veneer/Weatherboard).
• Pitched Roof/Raked Ceiling.
• Pitched Roof/Horizontal Ceiling.
• Thermofoil Installation to Timber Studs.
• Thermofoil Under Tiled Roof.
• Thermofoil Under Metal Roofing.

Metal Deck Roof.
1. The insulation mater ial shall be Glasswool or

Fibertex™ Rockwool Anticon™ R1.5, R2.0, R2.5 or
Glasswool Acousticon™ as manufactured by CSR

2. The insulation material shall be dry when installed
and shall be kept dry.

3. a) For timber purlins up to 900mm centres:
The insulation material shall be rolled out over
the purlins allowing an even sag between them to
provide sufficient space for the thickness of the
insulation. Ensure that adjacent edges are tightly
butted together. Foil facing shall be on the under
side for cold and temperate climates, or on the
upper side for tropical climates.

Where maximum resistance to the penetration
of water vapour is required - add:

The 150mm wide foil overlap shall be sealed to the
underside of the foil on the adjacent insulation by
means of an approved contact adhesive or vapour
impermeable pressure sensitive tape, applied in
accordance with the manufacturer’s recommendations.

b) For steel purlins, and for timber purlins
above 900mm centres:

Install wire safety mesh across the purlins. The wire
shall be dished in accordance with the following:

R1.5 – dish minimum 55mm
R2.0 – dish minimum 75mm
R2.5 – dish minimum 95mm

and sufficient to accommodate the insulation

allowing it to perform to the specified value of the
insulation. The edge wires of adjacent runs shall be
twitched together at approximately 450mm centres.

4. The insulation material shall be rolled out over the
wire mesh, ensuring that adjacent edges are tightly
butted together. Foil facing shall be on the under
side for cold and temperate climates, or on the
upper side for tropical climates.

Where maximum resistance to penetration of
water vapour is required - add:

The 150mm wide foil overlap shall be sealed to the
underside of the foil on the adjacent insulation by
means of an approved contact adhesive or vapour
impermeable pressure sensitive tape applied in
accordance with the manufacturers recommendations.

TABLE 12. RECOMMENDED
INSULATION R-VALUES FOR
COMMERCIAL APPLICATIONS.

Location Ceiling Walls

Australia
Brisbane R1.5 R1.5
Canberra R2.5 R2.0
Darwin R2.5 R2.0
Hobart R2.5 R2.0
Melbourne R2.5 R1.5
Perth R2.0 R1.5
Sydney R1.5 R1.5

New Zealand R2.5 2.0
Asia

China R2.5 R2.0
Singapore R2.5 R2.0
Thailand R2.5 R2.0
Indonesia R2.5 R2.0
Taiwan R2.5 R2.0
Malaysia R2.5 R2.0

INSULATION/PROFILE MATCHING.
Most profiles have been installed with all R Values of

Anticon™, without distortion of the roof line. Refer to
Table 13 for a guide to fixing screw length or refer to
the Metal Deck manufacturer for further information.

If Klip-Lok™ is to be specified with R2.5 Glasswool
Anticon™, the use of a roofing spacer such as Bradford
Thermodeck™ is recommended, subject to engineer’s
agreement, to allow for recovery of the insulation and
ensure roof profile is even.

For surfaces where premium resistance to
mechanical damage is required, specify Anticon™ R1.5,
R2.0 or R2.5, incorporating Heavy Duty 750 Thermofoil™.

System Specifications.

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absorption coefficient (α):
attenuation:

decibel (dB):

flanking transmission:

frequency:

reverberation:

British thermal unit (Btu):

calorie (cal):

capacity, thermal or heat::

conductance, thermal:

surface heat transfer
coefficient (f):

conduction

conductivity, thermal (k):

convection:

dewpoint

emissivity

humidity, absolute:

humidity, relative:

Kelvin K:

permeance:

permeability:

resistance, thermal:

resistivity, thermal:

specific heat:

transmittance, thermal or
overall heat transfer
coefficient

The ratio of the sound absorbed by a surface to the total incident sound energy.

The reduction in intensity of a sound signal between two points in a transmission system.

An acoustic unit of sound level based on 10 times the logarithm to the base 10 of the
ratio of two comparable sound intensities.

The transmission of sound between two points by any indirect path.

The number of vibrations per second. The unit is the Hertz (Hz), equivalent to one
complete oscillation per second.

The persistence of sound within a space due to repeated reflections at the boundaries.

Heat required to raise the temperature of 1 lb of water 1°F.

Heat required to raise the temperature of 1 gram of water 1°C.

Heat required to raise the temperature of a given mass of a substance by one degree
This equals the mass times the specific heat in the appropriate units (metric or imperial)

Time rate of heat flow per unit area between two parallel surfaces of a body under
steady conditions when there is unit temperature difference between the two surfaces.

Time rate of heat flow per unit area under steady conditions between a surface and air
when there is unit temperature difference between them.

Heat transfer from one point to another within a body without appreciable
displacement of particles of the body.

Time rate of heat flow per unit area and unit thickness of an homogeneous material
under steady conditions when unit temperature gradient is maintained in the direction
perpendicular to the area.

Heat transfer from a point in a fluid by movement and dispersion of portions of the fluid.

Temperature at which a sample of air with given water vapour content becomes
saturated when cooled at constant pressure.

Capacity of a surface to emit radiant energy; defined as the ratio of the energy emitted
by the surface to that emitted by an ideal black body at the same temperature.

Mass of water vapour per unit volume of air.

Ratio of the partial pressure of water vapour in a given sample of air to the saturation
pressure of water vapour at the same temperature.

The unit of thermodynamic temperature. For the purpose of heat transfer, it is an
interval of temperature equal to 1°C.

Time rate of transfer of water vapour per unit area through a material when the vapour
pressure difference along the transfer path is unity.

Permeance for unit thickness of a material.

Heat transfer through space from one body to another by electromagnetic wave motion.

Reciprocal of thermal conductance, or ratio of material thickness to thermal conductivity

Reciprocal of thermal conductivity.

Ratio of the thermal capacity of a given mass of a substance to that of the same mass of
water at 15°C.

Time rate of heat flow per unit area under steady conditions from the fluid on one side
of a barrier to the fluid on the other side when there is unit temperature difference
between the two fluids.

APPENDIX D.

Terminology.
ACOUSTIC.

THERMAL.