This guidance note provides advice on the principles, risks,
materials and methods for insulating dormer windows.
Dormers come in a large variety of shapes, sizes and materials
and can be a difficult area to insulate, but if insulation is left out
or is poorly detailed then the energy efficiency of the whole
roof can be compromised.
Retro-fitting insulation to any existing building is not
straightforward, even if it is of relatively recent construction.
Considerable ingenuity and attention to detail is required to
ensure that the insulation is installed effectively at every
awkward junction and gap. Solutions will normally need to be
individually designed for each situation and professional advice
will often be required. This guidance discusses approaches to
these challenges in general terms, but cannot advocate
standard solutions because of the complexities involved in
individual cases.
Dormer windows are a very prominent feature of many historic
buildings and changes in their proportion or external detailing
are rarely acceptable. This is particularly important if their
design reflects that of other windows below or of dormer
windows in neighbouring buildings. The insulation of dormers
in historic buildings should be discussed in advance with the
local authority conservation officer.
The upgrading of dormer windows should wherever possible
be undertaken in conjunction with general roof upgrading work