Issue 47 JUNE - Flipbook - Page 33
Despite the perils associated with old buildings, it is worth
remembering that the construction methods used in the
past were generally a lot simpler than those used today,
and most traditional materials are natural and more
healthy, both for the building and the occupants, than
many of their modern equivalents.
Together with draught proofing, retrofitting to achieve
fabric first solutions involves jobs ranging from quick wins,
such as loft insulation, to potentially complex projects,
such as installing internal or external wall insulation. Wall
insulation should never be undertaken without the advice
of experts since interstitial condensation can result if
inappropriate materials are used or installed incorrectly.
The general message is that simple is best; before thinking
about heat pumps and other technology, the focus should
be on ensuring the building’s fabric works as well as it
possibly can. This fabric first principle concentrates on
cutting draughts and improving the thermal insulation
of the building envelope - the roof, floors and walls,
including the doors and windows.
Much easier than wall insulation is adding secondary
glazing to windows and, where appropriate, doors.
Draughts around the edges of sashes and casements and
chilly single glazing lead to cold areas close to windows,
so there is a tendency to move away from them.
Secondary glazing is an excellent way of overcoming this
problem while allowing the retention of old windows and,
importantly, their original glass.
Heat is lost much faster through air leakage than through
areas lacking insulation, so reducing the amount of cold
air getting in and warm air escaping saves energy and is
often achieved relatively easily and inexpensively. Creating a building envelope that is as airtight as possible helps
prevent discomfort and reduces the desire to turn up the
heating as being in a draught has the effect of making us
feel colder than we actually are. Consequently, sealing
gaps between floorboards and around doors and windows
is incredibly beneficial.
Old glass is particularly special due to the ripples and occasional bubbles that result from manufacturing ‘defects’.
These have the wonderful effect of bringing the glass to
life as it sparkles in the sun - an attribute sadly lacking in
modern glass, which appears flat and lifeless.
Secondary glazing takes many forms, from simple DIY
products to highly bespoke solutions. The type chosen will
depend on the window, its prominence within the
building and the budget available.
Airtightness should not be confused with breathability,
which is essential to how the fabric of an old building
works to prevent damp and the disastrous consequences
of woodworm and rot. Breathability has to do with the
movement of water vapour, not air movement or draughts
through gaps and joints. Even so, it is vital to understand
that increasing the airtightness of a building reduces the
number of air changes that occur and results in increased
relative humidity and poor indoor air quality. Ventilation
is essential but it must be controlled, rather than the random ventilation associated with draughts. It may be
achieved simply by opening a window for a brief period
or, more commonly, by a mechanical extractor such as
those found in bathrooms and kitchens.
With any work to an old building, it is essential to avoid
the perils of storing up problems for the future through
inappropriate interventions, so think about how it may
affect the way the building works and the aesthetic impact
it will have. If in doubt, consult a professional and, with
listed buildings and those in conservation areas, speak to
the local authority conservation officer and, where
necessary, gain the appropriate consents.
For further information, please visit
www.mitchellanddickinson.co.uk
i
i
Conservation & Heritage Journal
31
