INSULATION
The importance of
membrane solutions
Janeeth Devgun, insulation and external category manager at CCF, discusses how modern membranes have
evolved to provide a myriad of solutions for buildings
There is usually a lot of emphasis
at the specification stage
on choosing and installing
insulation in buildings, but it is
often forgotten that selecting a suitable
membrane is also a crucial requirement.
Without the right membrane, the
roof, walls, and floors of a building are
more vulnerable to moisture build-up,
condensation and mould.
However, modern membranes are
more than moisture barriers, and
therefore can provide a host of benefits
for a variety of different structure types
and applications.
The types of membrane
The most common types of membrane
are ‘air and vapour control layers’
(AVCL) and ‘breathable membranes’.
AVCLs are internal membranes that
control air and moisture, and breathable
membranes increase external water and
airtightness. Both provide the essential
barrier needed to protect the property
from becoming damp and from losing
heat through the roof, walls, and floor. A
new building must undergo airtightness
testing and be assessed under Part L of
the Building Regulations.
Timber frame buildings will be more
susceptible than steel structures to
things like mould build- up. However,
metal is prone to condensation build-up
on the underside of the sheet, which can
lead to trapped moisture dripping onto
and deteriorating the insulation. In both
cases, the roof is the most vulnerable area
for moisture to affect, especially in rainy
areas of the country, so it is an important
part of weathering the building.
Choosing an external membrane with
high vapour-permeability, combined with
good water-resistance, means that the
insulation is kept in a dry environment
and will continue to work effectively.
Products such as Tyvek Reflex heat
reflective membrane helps to improve
thermal efficiency by reflecting radiant
heat in summer and reducing convective
heat-loss in winter. Because of frequent
weather changes in the UK, internal
AVCL products have a variable Sd-value,
meaning it is designed to adapt to changes
in climate.
During the winter, the Sd-value of
the membrane increases as the relative
humidity within the building interior
DuPont
FlexWrap tape “Choosing an external
membrane with high
vapour-permeability,
combined with good
water-resistance, means
that the insulation is
kept in a dry environment
and will continue to work
effectively”
increases, reducing moisture transfer
towards the insulation. The Sd-value
decreases as the relative humidity drops
during the summer months, allowing
the construction to dry out towards the
interior.
Not only does the membrane need to
withstand the elements once the build
has been completed, but also during
construction. For this reason, there are
membrane solutions that can be left
exposed during the installation and
remain protected from UV and rain
exposure for up to four months in some
cases. This offers peace of mind should a
building be left exposed due to site delays.
To ensure a compliant end-result and
optimal results, it is important to use the
correct membrane tape. Not all tapes are
made the same and failure to use tapes
compatible with the chosen membrane
can lead to damage. Incorrect use of tape
can lead to water breaking the seal and
the building to then become inefficient
and uncomfortable to live in over time.
Product choice
The amount of choice on the market now,
when it comes to membranes, tape and
accessories, is growing. Opting to choose
leading manufacturers with proven and
tested products, compliant with UK
standards, is going to ensure the best
performance, safety, and the all-important
sales and aftercare support.
w www.ccfltd.co.uk
48 www.rcimag.co.uk July 2018
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