April 2018

normally achieved through heat welding with
most single-ply systems, but with Sika-Trocal
membranes this is also usually carried out with
solvent welding, making the process much
quicker and more efficient. In all situations, a
wind uplift calculation will need to be carried out
to determine the number of fasteners required, or
to establish if it is safe to install an adhered
system. Sika-Trocal licensed contractors can log
into the Sika-Trocal web-based programme where
they can generate their own wind uplift
calculations, all in accordance with the latest
European codes of practice.
Good outlets
Sika-Trocal single-ply membranes, especially the
mechanically-fastened type S system, will use
membrane-laminated profile metals at all
perimeters and change of angles within the
roofing system to restrain the membrane. Again,
these should be designed in accordance with BS
6229, therefore at upstand junctions the
minimum height should be 150mm above finish
roof surface. Once the main roof is complete, the
outlets and any penetrations can be completed.
Roof outlets will normally be supplied in rigid PVC
so the membrane can be fully-welded to these in
the same way as the laps of the membrane,
creating a watertight seal. Penetrations can also
be detailed using rigid PVC units or Sika-Trocal
“A wind uplift
calculation will need to
be carried out to
determine the number
of fasteners required,
or to establish if it is
safe to install an
adhered system”
laminated metals formed to suit the size and
shape of the detail. Standard UPVC pipes –
such as SVP pipes – can be detailed using
single-ply membrane and fully-welded to
ensure they are watertight. Any services or
freestanding plant that is to be located on the
roof surface will need sacrificial protection
layers installed to ensure the roofing membrane
is protected and to ensure there are no issues
with compatibility with the support feet and
pads of the units, plus the roofing membrane
itself.
The final step
To complete the roof, it may be required to install
a slip-resistant walkway in order to protect the
roofing system or keep foot traffic to a safe area
of the roof. These can be fully-welded to the
roofing systems, using various thicknesses such
as Sika-Trocal WBP20 or the HD walkway for
more frequent foot traffic.
Further items, such as lightning conductor
systems, are available using semi-rigid PVC
pads that simply weld down to the roofing sheets
at the required centres, making a very quick and
simple method of attachment. Fall arrest
systems are also manufactured using PVC
coated units in order to be fully-sealed to the
roofing membranes, again providing an easy
application.
Single-ply membranes are increasingly seen as a
simple, modern solution for the watertight
protection of a range of roofing applications.
However, nothing should be taken for granted
when it comes to their installation in order to
guarantee long-term performance.
Hopefully, this guide helps highlight a number of
seemingly smaller details which should be fullyaddressed
to ensure a single-ply membrane lives
up to its billing as the quality, roofing solution for
today and years to come.
Contact Sika-Trocal
01707 394444
gbr.sika-trocal.sika.com
@SikaTrocal
APRIL 2018 TC 39