Permitted Development Loft Conversions - Oct. 1st
The limits for erecting extensions to the roof of a domestic dwelling as part of a permitted
development loft conversion are much the same as the previous legislation. You still cannot erect a dormer or alter
the roof at the front of a property if it affronts a highway so no change there.
The installation of velux roof lights are still deemed permitted development as well although
they have now enhanced the wording with dimensional limits to ensure that the projection from the roof slope face
is minimised to no more than 150mm.
The volume limits are similar to before with 40 and 50 cubic meters being the maximum volumes to terrace &
other properties respectfully. There are now slightly tighter restrictions of where you can place a dormer window
within the roof slope which must now be no closer than 200mm to the eaves.
Ridge height restrictions still apply in so far that the roof extension must not exceed the existing roof ridge
Side windows are also controlled under permitted development for loft conversions in so far that it shall be
obscure glazed and any opening sash must be at least 1.7M above the floor level in an attempt to prevent the
potential for overlooking.
The formation of balconies, verandas & raised platforms are also prevented under permitted development for
loft conversions. Article 1(5) land mainly being conservation areas and areas of outstanding natural beauty (AONB)
also prevent roof alterations under permitted development. A new criteria of preventing roof alterations under PD
relates to the installation or removal of chimney stacks, flues and soil vent pipes.
Download a pdf guide for Permitted Development on loft
guidance on permitted development and loft conversions
Most loft conversions constructed under permitted development are still exempt from planning if it merely
converts the existing roof void without any new projections or volume being created externally. However, always
check the previous planning history of the site in case any previous planning permissions removed the sites
permitted development rights or sought to control the future use of the existing roof voids.
The biggest benefit of the new permitted development wording for loft conversions or roof alterations is the
fact that it s no longer tied in with the volume allowances of any other extensions to the property. Previously 70
cubic metres was your total ‘all in’ allowance and if this was already taken with a single storey rear extension
for example, you would not be allowed any extra dormer volume for example unless you obtained formal planning
As always, you are advised to obtain professional drawings completed by a Building Designer which can be used as
part of a formal Certificate of Lawful Development application to the Council that will formally and legally
confirm that your project is indeed permitted development.