January 2019

Single Ply Roofs
INSTALLING A SINGLE PLY ROOF:
WHAT YOU NEED TO KNOW...
The Technical Team at Bauder talk through the key steps to installing a single ply roof.
BS 6229 states that a minimum finished
fall at any point of 1:80 (1.25%) should
be achieved which includes any formed
internal gutters; this will reduce slip hazards and
deposition of fines leading to plant growth, as
well as minimising water ingress and damage if
there is a leak.
It is worth considering the guarantee required
on completion of the installation. If a Product &
Workmanship guarantee has been requested by
the client, then Bauder site technicians require
access throughout the period of installation to
ensure compliance with our design criteria and
installer guidelines.
If there is a likelihood that mechanical damage
may take place to the recently installed
membrane due to other trades using the roof as a
working platform, then an adequate protection in
the form of timber boards on a protection fleece
must be put in place. Ideally, once the membrane
roof has been installed then the flat roof area will
not be accessed other than for essential
maintenance.
Maintenance of a single ply membrane roof is
recommended twice yearly (autumn & spring) or
after a major storm. Checking should include
for – but not limited to – blocked outlets, debris,
overhanging trees, perished sealants and
termination details.
Contact Bauder
0845 271 8800
www.bauder.co.uk
@BauderLtd
Bauder’s key considerations when
installing a single ply roof:
1. Correct documentation on site
Before work commences it is important there is
a copy of the NBS specification available to all
operatives along with any tapered drawings,
technical drawings, adhesive and mechanically
fixed installation guidelines if required.
2. Air and vapour control layers
You need a self-adhesive or mechanically fastened
VCL. For polyethylene, you need the tapes (03 &
20) for sealing the joints of the VCL on the field
and upstand areas. All VCLs should extend up to,
but not beyond, the height of the insulation.
3. How is the insulation being installed?
If the insulation is adhered and the VCL is KSD Foil
or DBR then it has a foil finish; if the Insulation is
FA or FA-TE then you must use the Twin Cartridge
Insulation Adhesive. Ensure the board joints are
taped using a self-adhesive foil tape when using
Thermofol Contact Adhesive-Drum.
4. Fastener layout
This will enable you to ascertain the correct
fixing pattern for a mechanically fixed system.
5. Use the correct membrane adhesive
Refer to the adhesive suitability table in the
Bauder price list to ensure that you are using the
correct adhesive based upon the application,
membrane and substrate.
6. Thermofol PVC membrane laps should
be heat welded at a temperature of
between 450 & 500ºC
Heat welding is performed at temperatures
between 450 and 500°C and is a 3-stage
process for seams. The membrane should be
tack welded at 2m centres to assist with
tensioning and removal of any creases. A preweld
is created by performing a continuous weld
in the rear of the overlap so that an open pocket
with a width of approx. 40mm is formed for the
final weld. The final weld is created by leading
the pressure roller 20-30mm ahead of and
parallel to the 40mm weld nozzle. Indicators of a
good final weld are a strong shine next to the
weld and slight smoke build up.
7. Order accessories in advance
There is a vast array of single ply accessories
available to assist in reducing vulnerable detailing.
Pre-fabricated corners, outlets, un-reinforced
detailing membrane, lightning conductor clips etc.
8. Pre-fabricated metal and / or bar
restraints
When there is a change of direction on the roof it is
good practice that a hard angle is installed to
protect the insulation (in the case of a warm roof)
and to restrict the peel forces that are placed upon
the membrane in these locations. Pre-fabricated
metal should be employed at all exposed details
such as a drip or water check curb.
9. Carry out a weld check
Let the weld cool down sufficiently, then use a
weld tester probe. Place the probe on the weld
using medium pressure and move along the
weld. Do not use a scriber. Should capillaries or
open welds be found, carry out the necessary
remedial action.
10. Inspections
Once the project is complete it is important that
a Bauder site technician is provided access to
the roof prior to the scaffold being removed to
sign off the roof.
42 TC JANUARY 2019