Insulate - The Essential Insulation Magazine - May 2018

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Insulate Columnist
The Challenges of Surveying
Cavity Wall Insulation
Ben Gardiner MRICS, Director of Egerton Surveying Ltd
Chartered building surveyors working in the residential property sector undertake a range of different
instructions and services for clients. Many chartered building surveyors are now working with clients to
provide technical assistance in relation to retro-fit insulation measures. Few insulation measures polarise
opinion as much as cavity wall insulation (CWI). Many people have benefited from improved insulation within
their cavity walls. Whilst others have suffered greatly from penetrating dampness, condensation and mould. Where
damage has allegedly been caused, surveyors such as myself specialising in this field face a problem that is often
complex to evaluate.
As a member of the Royal Institution
of Chartered Surveyors (RICS), I am
governed by professional and ethical
standards in all work I undertake.
I am duty-bound to undertake all
surveys in an unbiased manner regardless
of how the occupant, claims
company, solicitor etc, may wish
to influence proceedings. Specific
CWI surveys and reports form a
large proportion of the instructions I
personally receive. However, for most
residential surveyors carrying RICS
HomeBuyer Surveys (Level 2 survey)
and Building Surveys (Level 3
survey), it is an area in which they
have limited experience. As a consequence,
it can be difficult for CWI
to be adequately assessed and home
buyers properly advised.
A specific CWI survey involves a
thorough whole-building inspection,
similar to a RICS Building Survey.
For example, it requires a similar
amount of time spent at the property,
an in-depth assessment of the building’s
performance and defects and a
carefully crafted report. The difference
is that neither a RICS Building
Survey nor a RICS HomeBuyer
Survey allow for intrusive investigations.
The ability to drill into a
cavity in multiple locations provides a
surveyor with valuable information as
to the performance of the CWI and
condition of the cavity. That being
said, there is a wealth of information
a residential surveyor can collect by
visual means only. When a surveyor
suspects that the performance of the
CWI may be compromised, the
following points should be
considered:
• Exposure to walls to wind driven rain (British Standard 8104:1992, Approved Document Part C of the Building Regulations)
• Drill pattern
• Size and condition of drill holes
• Cavity trays and weep holes
• Blocked or open air vents
• Location of internal dampness, mould and/or condensation
• Type of insulation (i.e. overspill in meter cupboards, roof voids, wall vents)
• Overall wall thickness
• Location and condition of damp proof course
• Internal temperature and relative humidity
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