SA Affordable Housing May / June 2017 // Issue: 64 | Page 23

FEATURES
A contractor installs insulation in a roof. Image: Pinterest
You will need to establish if you are trying to keep the
heat in, keep it out or both. Ceiling insulations are
effective against daily temperature changes as well as
seasonal changes.
CHOOSING CEILING INSULATION
When choosing the right ceiling insulation, there are two
main categories to choose from – reflective or bulk roof
installation. You can get an even greater insulating effect
by combining reflective and bulk insulation.
Examples of combined insulation would be factorylite,
which is aerolite combined with a reflective insulation.
Isofoil which is isotherm combined with a reflective
insulation. The R-value of the product determines the
products ability to resist heat flow. The higher the R-value,
the better insulating affect you will get out of the product.
AEROLITE AND ISOTHERM BULK CEILING
INSULATION
Bulk insulation is excellent for resisting convected and
conducted heat. The air pockets inside the insulation traps
the heat. Thermal resistance works the same way, and it
makes no difference which way the heat flows through it.
Additionally, bulk insulation and reflective insulation are
the two types of insulations currently on the market.
The leading bulk insulations are think pink aerolite, which
is a glasswool roof product. Isotherm ceiling insulation is a
polyester material. Bulk insulation comes with an R-value
that differs according to which thickness of insulation
you require.
REFLECTIVE INSULATION
Radiant heat flow is resisted by insulations with reflective
properties. This is achieved because the insulation is
highly reflective and it can re-radiate heat. There is a
25mm layer of air that the reflective insulation relies on
next to the shiny surface. Heat flows differently through
reflective insulation depending on which direction the
heat source is coming from.
Reflective foil is made from aluminium and is laminated
to paper or plastic. You can get a decrease in performance
from reflective insulation when dust settles on it as dust
reduces its ability to reflect. The shiny foil surface should
always face downwards. The anti-glare surface of single
sided foil should always face upwards or outwards.
Up and down R-values are supplied with reflective
insulation. You get a different R-value for each thickness.
Always make sure the values given by the manufacturer
relate to what you are looking for.
AFFORDABLE
SA HOUSING
MAY - JUNE 2017
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