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5.1 Things to Consider Before Constructing a Built-In Cavity / Enclosure
It is advisable to consider the following things before starting the construction of the built-in cavity.
Ash Lip Options
The Rangitata ULEB comes with optional ash lip, which helps to reduce the floor protector thickness
and depth. Depending upon the type of floor, workout the floor protector type, size, and thickness.
Front wall cladding
Thickness and type of cladding will determine the size and construction of the timber frame.
Elevation of fire above ground
The height above the ground determines the floor protector size and thickness. For installations with
elevation 300mm above ground will need only ash floor protector with 362mm depth.
Cavity venting
The built-in cavity for the ZC installation must be vented. It should have unrestricted air inlets both, at
the bottom of the cavity and air outlet at the top of the cavity with a minimum open area of 13600 mm
2
.
Air inlet at the bottom can be on the side or rear of the built-in cavity. Air can enter the built-in cavity
from the same room, adjacent room, or from the exterior. The air vents that are on the external walls
should be weatherproof. For both internal and external vents, the opening must be covered with an
appropriate mesh or similar to prevent vermin or debris from entering or blocking the airflow.
The built-in cavity can be vented at the top either using 300mm casing or vent situated close to the
top of the cavity, into roof space, or combination of these multiple locations. Both inlet and outlet vent
can be of any shape and size as long as they have an open area of 13600 mm2 minimum
.
Fig 12 shows the major four types of built-in cavities and venting options.
a) Exterior cavity – with exterior bottom vent and top vent, either using 300mm casing or side of the
cavity.
b) Interior cavity – with interior bottom vent and top vented into roofing space
c) Interior cavity – with internal bottom vent, top vented into the same room just below ceiling level
and into roofing space with a 25mm gap around 250mm casing.
d) Interior cavity – with interior bottom vent, top vented into the same room just below ceiling level
and further top portion of the cavity vented using 300mm casing or a side vent at the top of the
cavity.
Fig. 12 - Schematic Diagram for Built-In Cavities and Vents
Summary of Contents for RANGITATA ULEB
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