2 MAIN CONCEPTS
2.1 The amending Order introduces a number of concepts that apply to several of the classes of householder development. As these concepts are fundamental to interpreting and applying the new Order, they are explained in some detail in this section.
Principal Elevation
2.2 In the 1992 Order, development that could be within the public domain was controlled by reference to a distance from a road (e.g. the 20 metre rule). However, this can lead to the need for planning applications for minor forms of development if, for example, there is a rear lane behind the rear garden. This amending Order seeks to address this difficulty by applying different controls to the "front" and "rear" of a dwellinghouse. The principal elevation concept is the method used in this amending Order to identify the "front" and consequently the "rear."
2.3 The intention is to ensure that it is the public domain that is afforded the highest level of protection, whilst allowing householders greater flexibility in areas where there is less public interest.
2.4 Whilst there are exceptions, most houses are designed so that the "front" of the house faces a road. As it is the public face of the house, it will usually be designed to be the most important elevation or principal elevation. Having established the principal elevation, the rear elevation will be the elevation opposite the principal elevation. Side elevations will link the principal and rear elevation. Likewise, the front curtilage is all the land in front of the line of the main wall of the principal elevation. The rear curtilage is the remainder of the curtilage of the dwellinghouse.
2.5 It is recognised that not every dwellinghouse will be part of a conventional suburban street and that there will be endless variations in design and setting. However, it is considered that for the vast majority of houses it will be straightforward to identify which elevation is the principal elevation and hence establish the front and rear curtilages.
Definition
2.6 The definition for the principal elevation used in the amending Order states that the principal elevation, " means the elevation of the original dwellinghouse which by virtue of its design or setting is the principal elevation." Normally what is the principal elevation will be obvious and will be commonly understood as the elevation of the original dwellinghouse which fronts (directly or at an angle) the main road serving the house and by its design and setting is understood to be the front of the house. Where it is not immediately obvious, a combination of the following factors should be used to identify the principal elevation:
- Location of main door;
- Windows;
- Room layout;
- Relationship to road;
- Boundary treatment;
- Orientation of adjacent properties;
- Architectural ornamentation.
2.7 It is unlikely that any single factor will be decisive. The identification of the principal elevation should not be based on attempting to control development that might have a public visual impact. There can only be one principal elevation and it is based on the design of the original dwellinghouse.
2.8 The diagrams in Figure 1 illustrate how the principal elevation can be identified in a variety of common situations.
Figure 1: Identifying the Principal Elevation in a variety of common situations.
| The principal elevation is the elevation that fronts the road. It has the main door and is the obvious orientation of the dwellinghouse. The side elevation has no windows and has a shorter length. The rear area is more private with a higher fence |
| Although the side elevation has the main door and a longer length, it has only a secondary window. The windows in the principal elevation show the main orientation of the house and it fronts the road. The boundary treatment indicates a more private rear area |
| A corner plot will face two roads. However, the principal elevation has the main door and fronts the same road as the adjacent house. Opposite the principal elevation is the private rear area. The side elevation - although fronting a road and having windows - does not reflect the main orientation of the dwellinghouse. |
| In a Radburn type layout the principal and rear elevations could be identical. However, the overall setting and boundary treatment indicates which elevation would be understood as the "front" and "rear." The side elevation has windows and faces a road but could not be the principal elevation because it has no door and is opposite a blank wall. |
Notes: P = Principal Elevation, R = Rear and S = Sides.
Fronting a Road
2.9 Identifying the principal elevation is important in the definition of the front and rear curtilages. It is also used in a number of classes as a way of describing a restriction on permitted development. For example, in Class 1 (single storey ground floor extensions) such a limitation states, " any part of the development would be in front of the principal elevation or side elevation where that elevation fronts a road".
2.10 In this context an imaginary line can be drawn that extends from the principal elevation or side elevation to the boundary. " Fronts" means facing onto a road and this applies to both the principal and side elevations. This is demonstrated in Figures 2 and 3 below, which illustrate the concept in common situations. The definition of road in the 1992 Order has the meaning assigned to it by section 151 of the Roads (Scotland) Act 1984, and this definition will apply to the new classes. In brief a road is any way over which there is a public right of passage including its verge. A road is therefore not confined to only publicly adopted roads used by motor vehicles.
Figure 2: Both the principal and side elevations front a road. Any extension, other than a porch, falling within the hatched areas would require planning permission.
Figure 3: If the principal elevation of a dwellinghouse is stepped, or contains bay windows, the line of the wall follows the contours of the dwellinghouse. Any extension, other than a porch, falling within the hatched area would require planning permission.
Situations where an elevation may not front a road
2.11 There are circumstances where neither the principal nor the side elevations front a road. In such cases, development extending beyond the main wall may be permitted development subject to compliance with other criteria in any given class. The diagrams in Figure 4 illustrate situations where an elevation may not front a road.
Figure 4: Common situations where an elevation may not front a road
 | Where there is no road. In this example, development would be permitted within the curtilage of the dwellinghouse at the top of the diagram as long as it meets the site coverage, distance from boundary, height restrictions any other relevant restrictions for the type of development. |
| Where the dwellinghouse is sited at an angle. If an elevation is sited at a very acute angle to a road, it may not be considered to front a road. In this illustration the dwellinghouse is sited at 45 degrees and is therefore judged to front a road. Any extension within the hatched areas would require planning permission If the dwellinghouse were to be rotated, the principal or side elevation may no longer front a road. |
| As the road bends, the side elevation no longer fronts the road. If the dwellinghouse was rotated clockwise, by around 45 degrees, the side elevation would front the road but the principal elevation would not. Any extension within the hatched areas would require planning permission. |
| Within 20 metres of a road it is considered unlikely that any elevation could be argued to be too far from a road so that it no longer fronts a road. Beyond 30 metres from a road, it is increasingly likely that an elevation no longer fronts a road. For distances in between, a judgement would have to be made depending on fact and degree. This will involve considering factors such as topography, landscaping and layout of any adjacent properties. In this example, any developments would be permitted within the curtilage of the development as long as it meets the site coverage, distance from boundary, height restrictions and any other relevant restrictions for the type of development. |
| If there is intervening land between the curtilage of a dwellinghouse and a road, it could no longer be argued as fronting the road. In this example, any development would be permitted within the curtilage of the development as long as it meets the site coverage, distance from boundary, height restrictions and any other relevant restrictions for the type of development. |
Site Coverage
2.12 In a number of Classes the amending Order introduces a limitation relating to the site coverage which relates to the maximum site coverage of the rear or front curtilages. In most circumstances, the limitation will only relate to the rear curtilage. However, where the principal or side elevation does not front onto a road, the limitation could also apply to the front curtilage.
2.13 Curtilage is not defined in the proposed Order but there is case law from which its meaning can be summarised as "land which is used for the comfortable enjoyment of a building and which serves the purpose of that building in some necessary or reasonably useful way. It need not be marked off or enclosed in any way". Normally the curtilage would relate to the property boundary of the dwellinghouse. However, it may be a matter of judgement in the case of a farmhouse set within agricultural land or a large manor house set within extensive grounds.
2.14 The front and rear curtilage is defined by reference to the principal elevation. Again, an imaginary line has to be drawn. This line is the basis for calculating the site coverage and not any particular division of the curtilage that may exist on the ground. In drawing the imaginary line, the same approach to subsidiary structures and stepped main elevations should be used as discussed above. This concept is illustrated in Figure 5.
Figure 5: Identifying front and rear curtilages.
| Illustration of the definition of the front and rear curtilage. |
 | Illustrating the definition of the front and rear curtilage in the case where the principal elevation is stepped. |
2.15 If, as a result of proposed development, the total developed area of the rear curtilage (excluding the footprint of the original dwellinghouse) will exceed the total undeveloped area of the rear curtilage (excluding the footprint of the original dwellinghouse) then planning permission is required. In many instances there will be no need to carry out detailed measurements and calculations because it will be clear if the area of undeveloped land will exceed the footprint of both proposed and existing development (excluding the footprint of the original dwellinghouse). If a calculation does prove necessary, Figure 6 illustrates how the site coverage can be calculated.
Original or Existing Dwellinghouse
2.16 In interpreting the Order, it is important to differentiate between the original dwellinghouse and the existing dwellinghouse. The original dwellinghouse is the dwellinghouse as it was on 1st July 1948 or as built. The definition also refers to the special situation for Crown development but this is unlikely to apply frequently. The existing dwellinghouse is the dwellinghouse immediately before carrying out the development proposal that is being assessed. It does not include any outbuildings, even where they were built at the same time as the original dwellinghouse.
Figure 6: Calculating the area of site coverage
 | A - Original Dwelling House including a garage built before 1948; B - An extension built as permitted development in 1968; C - A conservatory granted planning permission in 1996; D - A swimming pool built as permitted development in 1975; E - A green house built before 1948. |
Site coverage In this example the total developed area for the purpose of the Order comprises: the extension (B); conservatory (C) and swimming pool (D) since these developments occurred since 1948 , together with the green house (E) as it was not attached to the original dwelling house. Therefore, in this example | Percentage of site coverage = | Area of B + C + D + E + Proposal | X100 | | Area of rear curtilage minus the footprint of original dwellinghouse (A) |
If the site coverage will be more than 50%, of the rear curtilage in this example, planning permission is required. |
Heights and Ground Levels
2.17 The amending Order calculates the height of development from the lowest part of the surface of the ground adjacent to the building or structure. This only applies to Classes 1 to 6CB; in all other instances the height of the building or structure is calculated from the highest part of the surface of the ground adjacent to the building or structure.
Conservation Areas and listed buildings
2.18 The amending Order reduces the amount of permitted development in conservation areas and within the curtilage of listed buildings. Figure 7 below summaries the implications:-
Figure 7: Implications for Conservation Areas and Listed Buildings
Not Permitted Development in a Conservation Area or Curtilage of a Listed Building | Class 2 (an extension, other than a single storey rear extension)
Class 3 (Any alteration)
Class 4 (Extension to roof)
Class 5 (Any other roof alteration)
Class 6A (Any other development in curtilage)
Class 6B (Hard surface)
Class 6CA (Porch)
Class 6CC (Alteration to flat) |
Stricter Controls in a Conservation Area or within the Curtilage of a Listed Building | Class 1 (Single storey extension)
Class 6 (Outbuilding)
Class 6C (Decking) |
No Restrictions in a Conservation Area | Class 6CB (Fence) |
Definition of Enlargement
2.19 It is important to understand the definition of enlargement of a dwellinghouse and how the various classes inter-relate with each other. Classes 1, 2 and 4 relate to extensions and dormer windows which enlarge the dwellinghouse, whereas Classes 3 and 5 relate to alterations or improvements which do not.
2.20 Enlargement is defined as any development that increases the internal volume of the original dwellinghouse and includes a canopy or roof, with or without walls, which is attached to the dwellinghouse, but does not include a balcony. Therefore, a car port is an enlargement but a balcony is not.