clip clip hooray!
In this part of our Technical Troubleshooting series, Mat Woodyatt, technical training manager of BMI UK and
Ireland, looks at the requirements concerning mechanical fixing and the use of clips
By now, we should all know the
minimum fix for large format
interlocking tiles on a UK roof
off by heart! BS 5534: 2014 has
been with us for several years, and it was
launched with enough fanfare that few
could escape the wide-ranging changes
introduced to the industry. But still we see
roofs without adequate fixings.
Not only do we see a worrying lack
of demand for manufacturers’ fixing
specifications, a requirement of the
standard – and something all reputable
companies offer for free; but also, a
close inspection of many new roof
installations reveal that the fixings do
not meet even the very minimums of
It is easy to estimate, for example,
how many roofers are not clipping their
eaves course simply based on the ratio
of tiles to clips sold into the industry.
For the total avoidance of doubt: the
fix for interlocking tiles on a UK roof is
every tile once fixed, and all perimeter
tiles twice fixed as an absolute
minimum. It is the latter that often
causes the real head-scratching.
Verges and ridges?
Well: that box can often be ticked with
the use of a Dry Fix system, but did you
know that a Dry Fix Ridge, Hip or Verge
system only offers a mechanical fix (i.e.
the second fix) where the manufacturer
tells you it does. You cannot just
presume the case that all Dry Fix is a
And what about valleys like the
one in this picture? The result of
not properly fixing cut tiles into the
valley is apparent. Mortar cannot be
relied upon for a fix under the revised
standard, and even less so when it is
bedded directly onto lead. Lead moves
as the temperature changes and it takes
the mortar with it back and forth until
it falls away.
In a valley like this, we should be
seeing clips. Where we have a small cut
The result of
fixing cut tiles
into the valley
in the image
and have lost the nail hole, we need two
clips per tile to achieve out second fix
for the perimeter. Luckily there is more
choice than ever in that department.
Not only do we have the traditional
head and tail clips included in most
Dry Fix hip packs and sold separately
for valley details, we also have the Kro
Clip: a clip with a tail that works with
almost any tile and detail.
Yes: it is a little more work to fix
those tiles in place, yet a lot less work
and expense than climbing up to repair
the entire valley, not to mention the
risk of damage to the waterproofing
materials, which may cause expensive
damage to the property below.
For more information on BMI’s
training courses, visit the website
below or call the BMI National Training
Centre on 01285 863545.
82 www.rcimag.co.uk January 2019