September 2022

Tapered Insulation
TACKLING WINTER WEATHER & BILLS!
By Morgan Woolf, Technical Product Technician (South), Kingspan Insulation.
September is always a busy month for
roofers with owners looking to get their
properties ready to face the winter
weather. This year is looking especially hectic
with many trying to upgrade their building
insulation before bills go through the roof in
October. Poorly insulated flat roofs can account
for a lot of the heat loss from buildings and one
way to address this, whilst also ensuring effective
drainage, is by fitting tapered insulation. In my
role as a product technician at Kingspan, I’ve
been getting a lot of questions about these
systems, so here I’ll explain why tapered
insulation systems might be needed,
and what benefits they can provide.
Drainage
Despite their name, flat roofs will
almost always have a pitch of up to 10
degrees. This is to ensure that rain, sleet and
snow are all effectively channelled away. Without
this, the water will inevitably start to pond on the
surface, potentially leading to issues such as
alkaline formation and mould growth. The weight
of any water can also cause the surface to bow
over time, worsening the ponding and potentially
reducing the lifespan of the roof. If there are
obvious signs of ponding on a roof, it is important
to take action to reinstate the fall, ensuring the
structure achieves a fall of at least 1:80.
Insulation
As you’ve probably noticed, there’s been a lot of
change in the energy efficiency requirements
within the Building Regulations this year. England
introduced updates to Part L to the Building
Regulations (which governs energy usage) back in
June, with Wales due to introduce updates for
domestic properties on 22nd November 2022 and
new requirements for all properties in Scotland
coming into force from 1st December 2022.
These include limiting or improved U-values which
Above: Tapered roofing systems combine
insulation and a fall in a single, lightweight
system which is suitable for both new and
existing flat roofs. Left: Kingspan offer a
dedicated tapered design service to ensure the
required drainage and thermal performance can
be met with the slimmest system thickness.
contractors will typically need to meet, or improve
upon, when replacing or refurbishing an existing
flat roof. In all cases, the refurbishment work
needs to be appropriate for the particular project,
with consideration given to issues such as the
condition and construction of the building and any
ventilation or existing insulation within the space
below. All three countries provide some flexibility
in their target U-values to allow for this, however,
the values in the table above provide a good
starting point on most projects (see table above).
Why tapered?
Traditional methods used to create a fall include
fitting timber firrings (angled timber battens)
beneath a plywood deck, or laying screed to a fall
on a concrete deck. However, as the thermal
performance requirements for flat roofs have
increased, a growing number of contractors are
switching to tapered insulation systems which
provide insulation and a fall in a single system.
Tapered insulation systems typically include three
types of rigid insulation boards: tapered, hip and
valley and flat packer (which sit below the other
types of board). As the insulation boards
themselves are used to create the fall, the overall
system thickness can be slimmer than with the
alternative approaches, particularly where PIR
boards are used. They’re also much lighter than
screed solutions with no time lost waiting for
them to dry. In fact, if the existing roof surface is
in good condition, the tapered roofing can be
fitted directly above it.
To support installation of our tapered systems,
Kingspan Insulation offers a dedicated tapered
design service. Using your roof layouts, our
designers can quickly develop a system layout
which will provide effective drainage and meet your
target area-weighted U-value with the slimmest
possible construction. They’ll also handle the
condensation risk analysis and supply clear plans,
meaning you can get it installed in no time.
On-site support
If you’re thinking about fitting a tapered system
for the first time and want some support, or
simply need some advice on best practice, myself
and the other Kingspan Product Technicians are
here to help. We can visit most sites and give you
hands-on advice on the different tapered
insulation products and how to handle, cut and fit
them ready for the final waterproofing layer. We
also offer a remote product advice service.
To contact the team, email:
technicaladviseservice@kingspaninsulation.co.uk
Contact Kingspan Insulation
www.kingspaninsulation.co.uk
@KingspanIns_UK
46 TC SEPTEMBER 2022