Timber iQ December 2019 - January 2020 // Issue: 47 | Page 14

ASSOCIATIONS
Timber poles for
thatching structures
By the Thatchers Association of South Africa
Timber poles are an essential
component of a thatching structure.
As such, it is important that the
industry is well-informed about the
requirements of timber poles used in
thatching.
T
imber poles need to comply with the requirements
of SANS 457-2 or SANS 457-3, as relevant. Laths
and battens, which are also used in thatching, need
to comply with the requirements of SANS 1288, 1707-2
(eucalyptus), or SANS 1783-4 (pine), as relevant. All
timber must be preservative treated in accordance with
the requirements of SANS 10005. Poles uses for
structural elements must have a diameter of at least
100mm measured at thin ends.
If timber, such as a treated post, is planted in the ground it is
essential to allow for drainage of rainwater through the timber.
Any pole planted in the ground should be a minimum
classification of H4. If a treated pole is planted into the
ground, it is essential to consider the drainage of rainwater. A
structural engineer must be consulted for detailed structural
requirements in planting poles.
It is not correct to enclose the planted end of the post in
concrete. If concrete is used, then it must be allowed to form
a collar around the post with the end of the post protruding
through the concrete. If a post is going to be planted at the
bottom of the hole, it is important to allow the concrete to set
before planting the post.
The use and application of the correct H class of
preservative treated timber will ensure many years of
satisfactory service, which can be extended even further
with proper maintenance.
The science of treating timber properly provides for the
preservative to be deeply impregnated into the sapwood,
thereby giving a deep envelope of treatment around the
central heartwood. It is preferable that the treated timber is
purchased in the size for intended use. If this is not the case
and the timber need to be cut, the untreated heartwood of
the timber must be exposed. To retain the integrity of the
treatment, a generous amount of suitable preservative –
such as Creosote or CCA – must be applied into the cut
surface. The cut end of a pole or plank is not the end which
will be planted into the ground. It is advisable to plant the
uncut end into the ground. Anti-split plates should be placed
on the cut end.
There are specific considerations that need to be taken into account for poles used in thatching.
12
DECEMBER 2019 / JANUARY 2020 //
www.timberiq.co.za