|
When building (new buildings or additions) you are required to provide Termite protection.
Complying with building regulations.
Two
options are available:
1. Provide barriers against Termite
infestation to protect the whole building
2. Using Termite resistant materials
for all structural elements (partial
solution only)
To
comply with the Building Code of Australia
protection should be provided in accordance
with the relevant Australian Standards
(AS 3660) which describe protection
options that may utilise physical
barriers, Termite resistant materials
or combinations of these options.
Protecting
a building from Termite attack
Chemical
Barriers
The
use of chemical barriers to control
Termites in buildings requires licensed
operators. Chemical barriers must
be complete and continuous and be
maintained that way. Good site preparation
is needed to ensure uniform distribution
of the chemical. Chemical barriers
for Termite infestation have come
a long way since their introduction
and can now be used as an environmentally-friendly
alternative.
Physical
Barriers
Woven
stainless steel mesh -
this system consists of a fire woven
marine grade stainless steel mesh,
which is used as a physical barrier.
The mesh is too small for Termites
to pass through and too hard for them
to chew through.
Graded
stone particles -
consists of finely graded stone particles,
the proportion and dimensions of which
are strictly controlled. Graded stone
particles can be installed under concrete
slabs and suspended floor type systems
to form a continuous Termite barrier
in conjunction with other Termite
barrier systems and building practices.
The graded stone must be placed in
accordance with the criteria listed
in Australian Standard AS3660.1.
Sheet
materials
- usually formed from galvanised sheet
metal 0.5mm thick, the Termite shield
delays and impedes the passage of
Termites. Ant Caps must be placed
at all entry points to a building
in order to form an integrated system.
In the case of raised floor construction,
this would mean shields on top of
stumps and within any base structure
walling.
Visual
Barriers
Alternatively you may elect to use
a combination of the above mentioned
systems to protect your home.
It
should be noted that regardless of
the type of system installed, there
are no guarantees in keeping a building
free from Termite attack. Standards
and codes only minimise the risk.
As longevity of a building is an essential
element for an owner, there are several
options of treatments to choose from
and must make a concerted effort in
determining the most efficient and
effective solution for protection
against Termite infestation.
In
all cases one must ensure that inspections
are carried out on a regular basis
in order to monitor potential activity
of Termites.
AUSTRALIAN
STANDARD A 3660:1 - 2001
Overview
The
Standard has evolved from AS 3660
– 1993 and contains requirements
for both physical and chemical barriers.
The following is a brief overview
of what is contained in the Standard
and it must be stressed that a full
understanding of the contents can
only be achieved by reading the document.
This is particularly important as
a number of Sections within the Standard
are inter-related and an effective
barrier can only be achieved if all
relevant provisions are implemented.
AS
3660.1 introduces a number of new
concepts in relation to Termite protection.
The underlying philosophy of the Standard
is to provide a flexible approach
to Termite control, in that a number
of different types of barriers may
be used, provided each barrier interlocks
with the adjoining barrier to form
a complete system.
The
type of Termite barrier installed
in a building will need to be carefully
considered at the design stage, because
most systems will need to be installed
during the early stages of construction
(Local Building Authorities, including
Private Certifiers as appropriate,
will also need to approve the system
at building approval stage). Issues
that will effect the choice of system
include:
-
Termite activity in the area
- type of building design (e.g,
suspended slab on ground floor)
- level of maintenance desire
- landscaping adjoining the
building
SLAB
ON GROUND CONSTRUCTION
Protection of Areas Beneath a Slab
Table 2.1 of
AS 3660.1 details the methods that
may be used to protect beneath slab-on-ground
construction. Part 1 of the Table
relates to a concrete slab designed
to form an integral part of the Termite
barrier and Part 2 relates to a concrete
slab not used as a Termite barrier.
The
Slab as a Barrier
Part 1 of Table
2.1 applies to a concrete slab, designed
and constructed in accordance with
AS 2870 to form a part of an acceptable
Termite barrier. A slab which does
not confirm to AS 2870 cannot be used
a barrier.
Penetrations through the slab are
required to be protected either by
chemical spray or a physical barrier
such as Termite-Mesh.
Perimeter
Protection
Table 2.2 completes
the protection requirements for concrete
slabs. The perimeter of a slab on
ground is a common route for Termites
to gain access to structural members.
This are must be protected by one
of the options listed in the Table
which include chemical application
(similar to the Part B application
requirements listed in AS 2057) or
a physical barrier using graded stone,
stainless steel mesh or the exposed
edge of the slab.
Slab
Edge Exposure
An exposed clean edge of a concrete
slab, 75 mm above adjoining ground
level is considered to form as acceptable
perimeter Termite barrier.
The
effectiveness of this approach depends
on the external exposed edge of the
concrete being free of any imperfections,
fixings or render that could conceal
Termite activity
SUSPENDED
FLOOR CONSTRUCTION
General
AS 3600.1 has
introduced specific requirements on
Section 2 for Subfloor Ventilation
and access to facilitate ongoing inspection
and maintenance and to reduce the
likelihood of excessive moisture build
up which is conducive to Termite activity.
The details of these provisions is
summarized as follows;
Subfloor
Ventilation
Openings of 6,000 m2 per lineal metre
are required for both internal and
external walls.
Subfloor
Access
A minimum clearance of 400 mm between
finished ground level and the underside
of structural elements is required.
A reduced clearance of 150 mm if permitted
for the first 2.0 metres on sloping
sites.
Termite
Shielding
Description
A durable Termite resistant material
is used to create a shield that is
incorporated into the building structure.
Materials suitable for Termites shields
include:
- Galvanised Iron, minimum
thickness 0.50 mm.
- Zincanneal Steel, minimum
thickness 0.50 mm.
- Sheet Copper, quarter hard,
minimum thickness 0.40 mm.
- Stainless Steel Mesh of a
size appropriate to the species.
- Aluminium Alloy, minimum
thickness 0.50 mm.
Application
Suitable for suspended floors.
Installation.
Shielding is places in walls and above
stumps and piers in the subfloor area
of a building to create a continuous
barrier between the upper levels of
the building and the adjoining ground.
The barrier is designed to force any
Termites activity (especially within
the cavities of the masonry) to the
outer edges of the barrier where regular
inspection may detect any Termite
galleries that may bridge around the
barrier.
Masonry
Walls:
The shield must span across the entire
width of the masonry wall. On the
external face (outside face of brick
work) of the wall the barrier should
be visible within the brick mortar
course. On all internal masonry walls
the barrier must protrude 40 mm beyond
the brick work.
Stumps
and Piers:
This shield must be in the form of
a cap that extends at least 40 mm
beyond the finished face of the stump
or pier.
SYSTEMS
SUITABLE FOR SLAB-ON-GROUND AND SUSPENDED
FLOOR CONSTRUCTION
GRADED STONE
Application
(graded stone)
A)
Concrete Slabs:
Full under slab
protection
Partial protection –
- penetrations and control joints
Perimeter protection
B)
Suspended
Floor:
Full protection
Stumps and piers
Masonry walls
STAINLESS
STELL MESH
Description
A durable material resembling fly
wire in appearance with an appropriate
mesh aperture size that will not allow
the specific species of Termites to
work their way through.
The
mesh creates a barrier which forces
Termites out to the outer edges of
the mesh where they cab be readily
detected.
Application
(stainless steel mesh)
A)
Concrete Slabs:
Full installation.
Partial protection -
- penetration protection
- construction/control joints protection
- perimeter protection
B)
Suspended
Floors:
Galvanised Iron, minimum thickness
0.50 mm.
Zincanneal Steel, minimum thickness
0.50 mm.
Sheet Copper, quarter hard, minimum
thickness 0.40 mm.
Stainless Steel mesh of a size appropriate
to the species.
Aluminium Alloy, minimum thickness
0.50 mm.
CHEMICAL
SOIL BARRIERS
Application
(chemical soil barrier)
A)
Concrete Slabs:
Full protection
Perimeter protection
B)
Suspended Floors:
Masonry walls
Stumps and piers
NOTIFICATION
A durable Notice must be permanently
fixed to the building in a prominent
location such as a meter box or the
like indicating;
a) the method of protection, and;
b) the date of installation of the
system, and;
c) where a chemical barrier is used,
its life expectancy as listed on the
National Registration Authority label,
and;
d) the nee to maintain and inspect
the system on a regular basis.
|
