Most of our walls benefit from added
insulation and it is possible to add wall insulation to most construction types
used. Apart from these, an added wall insulation is vital in all climates. If
it is not already fitted, or if existing insulation levels are not high enough,
there are ways of installing it as a fit. Cavity brick walls have high thermal
mass, but without wall insulations are usually too cold in winter and often too
hot in summer if exposed to prolonged heat wave conditions. If the cavity is
insulated, the internal thermal mass is protected from external temperature
changes, and becomes highly effective at regulating temperatures within the
home. Insulate existing cavities by sealing the bottom of the cavity if it is
open to the subfloor, and pumping in loose bulk material to a measured density.
This has been common practice for many
years, usually in one of the following forms:
- Small
polystyrene balls (carbon dioxide produced) are coated in a non-toxic
bonding agent are pumped in at regular points around the building. The
bonding agent solidifies and locks all the balls in place.
- Mineral
fibers are put into the cavity either through a
series of small holes, as above, or into the top of the cavity if it is
accessible. Known as mineral wool, this material is treated with a
moisture repellent to keep the insulation and cavity dry.
Brick veneer walls have the brick skin on
the outside, which is not the ideal location for thermal mass. The bricks heat
up in summer and radiate heat late into the evening, while in winter they stay
cold and absorb heat from the house. Wall insulation is essential to protect
the occupants from external temperature extremes exacerbated by the external
brick skin. Reverse brick veneer is much more thermally efficient because the
thermal mass is on the inside; however, good insulation is still important to
maintain thermal comfort. Timber framed walls are low mass construction, and
rely entirely upon insulation to maintain thermal comfort. For timber frames,
wall insulation is pumped into the voids between studs and noggings, but this
can be labor intensive. The ideal option, if the scope of the renovation
permits, is to remove the internal plasterboard linings or external cladding
and fit insulation into the stud frame. Either bulk or reflective insulation
can be retrofitted to existing wall frames by either cutting up a roll and fitting
the pieces between each wall stud, or by using a factory prepared product such
as bulk batts, concertina foil batts or multi-cell foil batts, which are easy
to install and expand or fold into place. Reflective foil-backed plasterboard
is also a useful material. There is usually sufficient depth in a wall frame to
add more than one layer of reflective insulation, including the necessary air
gap of 25mm between layers. When installing from the room side, the foil should
not have an antiglare coating on it. Bulk insulation rated R2.0 (70mm) or R2.5
(90mm) can be fitted between studs in the conventional manner and, depending on
the thickness of the studs and the selected R-value, may or may not fill the
entire wall frame width. It is important to choose the correct thickness of
wall insulation to suit the thickness of the cavity.
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