| Not if
you buy the correct timber, argues Mike Hartley, Chairman and Managing
Director of John Brash. |
| “Debate continues
as to whether it is practical to grade on site. In all other areas of the
timber trade, this would not even be questioned, simply because ungraded or
incorrectly graded timber would not be tolerated with the same relaxed
manner. |
 |
| It is of course
accepted that battens do need to be graded and the grading rules that have
been set are designed to account for the loads that will be imposed upon
them. To help with this process, we have just updated our on-site grading
guide to reflect the recent changes to the new British Standards -
BS5534:2003 +A1: 2010. |
| The
new Standard rectifies an anomaly in the previous version that permitted an
excessively large knot that was almost 3/5th of the batten thickness,
equivalent to 15mm on a 25mm thick batten. |
| The
new standard has reduced the maximum allowable size of through-knots (a knot
appearing on both edges but not on the face) to only 5mm, significantly
smaller than the previous version’s 15mm. |
| There
is also now a requirement for battens to be straight, with specific new
tolerances for distortion that cover bow, twist and spring. |
| Whilst
these two defects were not historically found in most typical roofing
battens, rising timber prices has heralded alternative methods of cutting
battens and the defects have become more common. |
| That’s why John
Brash has consistently used the traditional side-board material for roofing
batten manufacture. With both trained staff, and stringent processes, in
place we ensure that any other type of sub-standard material reaching our
site is immediately identified and quarantined to prevent batch
contamination. That’s why we constantly urge all roofing contractors and
specifiers to check that the batten they are supplied with is either fully
factory graded, or manufactured from material that is suitable for on-site
grading by competent persons. |
 |
|
Ideally, a roofer should be presented with an independently certified, fully
graded product, which requires no grading on site. Many in the industry are
beginning to recognise this and adopting the stance that it shouldn’t be the
roofer’s problem to grade battens. |
|
Shades of grading |
| Of
course, the issue of grading is not in question here. The batten is such a
safety and performance critical element of the roof that it is universally
accepted that they should be graded. Therefore, there are two options
available to roofers: |
1) Buy
a fully graded batten that carries independent certification that it has
been graded and meets the standard.
or
2) Buy a batten to grade on site. |
| The
first option is the preferred route as it means that the batten is fully
compliant with BS5534:2003, the code of practice for slating and tiling. It
also means that the responsibility for ensuring the batten is to the
required standard rests firmly with the manufacturer, which reduces the
burden on roofers and allows them to concentrate on the job in-hand. This is
important as even the most proficient grading on site can be affected by
site conditions such as the weather and time pressures. |
|
One of the issues facing the industry is that
there are battens which claim to be graded but don’t carry this independent
certification. Without it, there is no way of knowing if the batten has been
correctly graded and if this is the case, alarm bells should be ringing.
John Brash became the first in the industry to offer JB-RED factory graded
battens, to BS5534:2003, which also carry the BRE ‘Tickmark’ 3rd party
accreditation. |
 |
| John
Brash’s JB-RED provides a factory graded batten that is fully compliant with
the new requirements of BS5534:2003 +A1: 2010, the code of practice for
slating and tiling. Our advice remains: beware of battens that claim to be
British Standard factory-graded but do not carry independent third party
accreditation. The Building Research Establishment (BRE) have carried out
tests, which showed that over half of the battens tested, which claimed to
be factory-graded BS5534:2003, fell well below standard – this is of great
concern. |
| It
continues to be an option to grade on site. However, this is only a
practical solution if the correct timber is used, in which case it can be
done by the roofer. Battens suitable for on-site grading should have already
been graded for rate of growth, slope of grain, rot and decay, dimension and
species. The only items to grade for therefore should be face knots and
wane. These can be assessed on site providing the grader has been trained to
do so. |
| Our
aim is to make life easy for the roofers when using battens, which is why we
offer factory graded battens as well as our newly updated on site grading
guide. |
| In
summary, if your supplier offers you factory graded battens to BS5534:2003
ask for independent assessment. If they have it they will give it to you. It
really is that simple. |
| For
information on the John Brash range of products visit:
www.johnbrash.co.uk
or telephone: 01427 675588. |
| |
