This article continues with the Government’s permanent Permitted Development Rights as set out in the regulations produced on 25 May 2019.
We look at additions etc to the roof which may include dormer construction for loft conversions.
Additions may not be permitted where the house was built under permitted development rights to change of use – as change set out in Classes M, N, P, A and Q of Part 3 of schedule 2 (subject to a further Article).
A). Any part of the permitted development or loft conversion should not exceed the height of the existing roof. If it does, then Planning Permission will be required.
The highest part of the roof of the existing dwelling house will usually be the main roof ridge line.
Chimneys, parapets, firewalls and other protrusions above the ridge line should not be considered when taking into account the height of the highest part of the roof of the existing house.
B). Any part of the dormer or roof extension should not extend beyond the elevation of the existing roof slope which forms the principal elevation of the dwelling house and fronts a highway.
For clarification, if any part of a dormer window as part of a loft conversion or any other enlargement of the roof space fronts a highway, then a planning application will be required.
Rooflights in a loft conversion on a principal elevation may however be permitted development providing the rooflight does not protrude from the roof slope by more than 150mm.
A rooflight that is situated on a roof slope forming the side elevation must be glazed using obscure glass. The rooflight should also be non-opening if below 1.7m above the floor of the room in which the window is installed.
C). The cubic content of the resulting roof space would exceed the cubic content of the original roof space by more than:
i). 40 cubic metres in the case of a terrace house, or
ii). 50 cubic metres in any other case.
For the purpose of section “C” resulting roof space means the roof space as enlarged, considering
any enlargement to the original roof space.
To be permitted development any additional roof space created must not increase the volume of a terraced house by more than 40 cubic metres and for a semi detached or detached house by more than 50 cubic metres. Any previous enlargements to the original roof space in any part of the house must be included in the volume allowance.
Alterations to a roof of a house for loft conversions involving the creation of balconies are not be permitted development and will require planning permission.
D). Planning permission will be required if on article 2(3) land National parks, the Broads, areas of outstanding natural beauty, conservation area and land within World Heritage Sites.
Development is permitted subject to the following conditions:
a). The materials used in any of the exterior work shall be of similar appearance to those used in the construction of the exterior of the existing dwelling house.
This condition is intended to ensure that any addition or alteration to a roof for a loft conversion results in an appearance that minimises the visual impact and is sympathetic to the existing house. This means the materials used should be of a similar visual appearance to those used in the existing house but does not mean that they need to be the same materials or match exactly.
Flat roof dormer windows will not normally have any visual impact and so, in this case, the use of materials such as felt, lead or zinc for the flat roof will be acceptable.
Cheeks of the dormer and the window should be finished to match the existing elements.
b). Enlargements to be constructed so that:
i). The eaves of the original roof are maintained or reinstated.
ii). The edge of the enlargement closest to the original eaves should not be less than 200mm measured along the roof slope.
iii). No part of the enlargement which joins the original roof to extend beyond the outside face of any external wall of the original dwelling house.
The measurement of 200mm should be made along the original roof slope from the outermost edge of the eaves (edge of the tiles or slates) to the edge of enlargement. Any guttering that protrudes beyond the roof slope should not be included in this measurement.
The above referred to permitted development permission does not stop the householder from applying for the following:
1. Building Regulation approval
2. Party wall etc Act 1996
3. Complying with Construction (Design and Management) Regulations 2015.
If in any doubt the Guild of Master Craftsmen recommend that you talk to and seek advice from your Local Authority Planning Department.