Most houses in England and
Wales benefit from permitted development rights that allow homes to be extended
without applying for planning permission. Whilst loft conversions and
conservatories are the most popular forms of extension under permitted development
rights, the General Permitted Development Order 2008 or GDPO is actually most
generous where outbuildings are concerned. This article looks at how to get the
most out of permitted development rights for outbuildings, garden rooms,
summerhouses, garden sheds and home offices.
Planning Applications and
Permitted Development
Permitted development rights
allow homeowners to extend houses by a certain amount without applying for
planning permission. This is helpful as a typical householder planning
applications will take at least 8 weeks to get approved and will often face a
surprising level of opposition.
Smaller schemes, however, can
be built under Class E of the General Permitted Development Order 2008 (GPDO).
While there is also an approval or checking process for schemes developed under
permitted development rights, this is not mandatory and is relatively simple.
PD rights are available on Green Belt land but can be affected by Conservation
Areas, Listed Building status and Areas of Outstanding Natural Beauty.
Size and Shape
Broadly speaking, you can
generally build up to 50% of the area of the curtilage (front and rear
gardens). Height will fall into one of three categories, depending on the roof
type and distances to the boundary.
The measurements for eaves
and total height are a little ambiguous in the GDPO. Fortunately, the key eaves
figure is the lower eaves, not the upper eaves or side. It is measured from the
top of the roof, at the lowest point at which it meets an outside wall.
Unfortunately, eaves height is measured at the top of the roof, not the
bottom.
Where sites are sloping, all
height measurements are relative to the nearest adjacent ground, except
for buildings within 2m of the boundary, where it is relative to the lowest
adjacent ground. There is little guidance on sculpting the local ground level
to increase the permitted building height but this is something you could
explore.
For most sites, we suggest
one of two basic building types, a flat roof scheme and a taller scheme with a
dual pitch (types A and C above). The base plan, details and interior of which
can be adapted to suit the site and your intended use. Simple variations could
include;
Porches / roof overhangs
Decks
Kitchens
WCs
Sliding glass doors and
windows
L-shapes, cruciforms and
complex plans
Gables on long elevations
Roofs following different
angles from the walls
You can find the exact
wording of the GDPO 2008 here or read the slightly more accessible guide from
the Department for Communities and Local Government here.
Uses
Under the permitted
development rights, outbuildings can be used for any purpose 'incidental to the
. . . personal enjoyment of the occupants of' the main house. This can include;
home cinemas
offices or study libraries
DIY workshops for personal
use
garages
TV and games rooms for
teenagers
pottery studios or hobby
spaces
snooker or billiards rooms
laundry rooms
Permitted development rights
do not cover living accommodation separate from the main house or 'primary
living accommodation such as a bedroom, bathroom, or kitchen'. Limited kitchen
and sanitary appliances can be installed, so long as they are neither totally
independent from the house, nor are they the main facilities for the house.
Performance
Weathertightness and low
maintenance will be a must for any summerhouse or outbuilding. Beyond that, you
might like to consider your own outbuilding in terms of;
heating requirements
electrical and data
connections
plumbing connections, sinks
and toilets
thermal efficiency
airtightness and ventilation
security
lighting quality and control
specialist fit-out such as AV
and IT or hobby related equipment
sustainable materials and responsible
sourcing
positive impact on
biodiversity
Construction
An ideal method of
construction would;
minimise wet trades on site
use prefabrication to limit
the time spent on site
provide cost security
limit the use of specialist
trades
make economies of scale where
possible
respond to physical site
constraints
visibly demonstrate sustainable
principles
Engineered timber I-sections
can achieve a lot of these goals and we suggest looking into products like Jewson’s
range of I-joists as a starting point.
External walls
External appearance of roofs
The choice of materials for
roofs will be strongly influenced by the size of the building and its impact on
the roof pitch. The larger the building, the lower the pitch, meaning less
choice of roofing materials.
Single ply membrane can work
at all pitches and can be adapted to suit a range of green roof systems. Green
roofs range from simple sedum blankets offering a visual greening for little
maintenance to 'extensive' systems which create habitat for wild flowers, bees
and butteflies.
We suggest looking into sedum
blankets over single ply membrane as a starting point for residential
outbuildings
I propose we offer sedum over
single ply as a starting point for all designs with an upgrade to intense
habitat roofs or a saving for bare single ply.
Moving forward
If you are reading this as a
homeowner or landlord and would like to know more, feel free to drop us an
email at studio425@london.com and we’ll be happy to help.
Sources and original documents
Original legislation
Planning Portal Interactive
House
Document