Tips and Guidelines for Planning Consent

Tips and Guidelines
for Planning Consent
Choosing the correct dormer
or rooflight for a Listed Property
W
hen converting
an attic or adding
an extension to a
Listed property, a
key issue is the provision of natural
light and ventilation. In order to
secure Listed Building Consent,
an appropriate arrangement of
dormers and/or rooflights will
be required. What is appropriate
depends very much on what type
of roof is proposed – its size,
angle, height and the type of
roof tiles used.
Many people prefer dormers because they
contain normal vertical windows which one
can stand in front of to see out. However
there is a limit to the number of dormer
windows a roof elevation can accept, and
there are many situations where use of a
dormer is not appropriate, either because
there is not enough space for it, or because
the disposition of the roofs or windows below
would make it look awkward or ‘out of focus’.
Whereas dormer windows are regarded as
architecture with a capital ‘A’ – i.e. they are
seen as significant architectural elements,
rooflights take a subsidiary role in the
architecture of a building and are therefore
a less conspicuous way of providing light
and ventilation. Moreover rooflights are
considerably less costly than dormers, and
they provide more light – about 20% more
than the equivalent sized vertical window on account of the fact that they point
upwards towards the sky.
The original Conservation Rooflight ®
from the Rooflight Company replicates
the traditional Victorian design and blends
seamlessly into the roof, making it favourable
to Planning and Conservation Officers.
Generally speaking windows look better
when they get slightly smaller on their way
up an elevation. This is not always the case,
but it is a good rule of thumb to follow. So
the windows framed by dormers should
ideally be a little smaller than the windows
of the floor below if visual harmony is primary.
The shape and style of the dormers should
closely follow local architecture; neighboring
properties will provide a good pointer for
the overall design.
As to rooflights, these need to be sensitively
detailed if they are not to detract from
Continued >>
Listed Heritage Magazine May/June 2014
3
the roof of a historic building. Generally
speaking the look of original cast iron
Victorian rooflights is preferred, as these lie
more or less flush to the adjoining roof tiles,
whereas many modern roof windows stand
somewhat proud of the roof and are chunky
in appearance. In a survey carried out with
Conservation Officers, flushness was the most
important characteristic cited for rooflight
design. The second most important feature
was size; don’t be tempted to install a larger
size than you require, particularly if it is a front
elevation as this is considered more sensitive
by Planning Departments compared to the
rear elevation. Further characteristics of this
type of rooflight include relatively fine glazing
bars and the glazing is generally split into long
narrow sections.
Smaller historic property was often extended
in an ad-hoc and organic manner. So whatever
means of admitting light and ventilation is
chosen for new additions or loft conversions
– dormers or rooflights – it is important to
recognise and keep to the spirit of the original
4
Listed Heritage Magazine May/June 2014
building. If the original was quite a formal
building then perhaps dormers lined-up with
windows below might be more appropriate.
Where the original building is informal, either
a mix of dormers and rooflights or rooflights
of different sizes would be more in keeping
with the original architecture.
When converting barns or stables, dormers
are simply not appropriate as they would
never have appeared on agricultural buildings
of this nature. Rooflights can work very
well, but there are two rules to ensuring
appropriate intervention. Firstly the rooflights
should be set out in a random way - not in a
row and secondly there should be variation
in size. As barns are part of our vernacular
architecture, a formal or ‘tidy’ approach may
look out of place.
In all cases it is best to consult your local
Conservation Officer at the earliest stage
in the design process. This will save time
and money.
SUMMARY OF TIPS
•Ensure you have a ‘conservation rooflight’
of an appropriate size as modern rooflights
do not have the correct features
•Dormers should generally be smaller the
further up the building they are placed
•Dormer windows are usually inappropriate
for barns and stables
•Rooflights on barns and stables should be
set out in a random way
•Contact you local Conservation Officer
to save time and money
Written by Peter King RIBA,
founder of the Rooflight Company
For further information contact:
The Marketing Department
www.therooflightcompany.co.uk
01993 833108
Listed Heritage Magazine May/June 2014
5