Rules for building Rear Extensions using Permitted Development

Transcription of the video

In this video, I go through the rules for building rear extensions under Permitted Development

This is video No 3 in a series of videos that started with Video No 1 considering eligibility for Permitted Development. Video No 2 listed the 10 conditions applicable to all extensions.

Rear extensions Time 0 00 1407
Rear extensions under Permitted Development

It is recommended that you watch videos 1 and 2 before you watch this one.

Looking first at a SINGLE-STOREY rear extension, the overall height cannot be more than 4m.

Rear extensions Time 0 00 3304 edited
Max height

The eaves of the rear extension cannot be higher than the eaves of the original house.

Rear extensions Time 0 00 3824 edited
Max eaves height

And, where the extension is within 2m of the boundary, the eaves cannot be higher than 3m.

Rear extensions Time 0 00 4721 edited
Max eaves height near boundary

The Maximum Depth

This increases if you secure prior approval for a longer extension.

Without prior approval ….A single-storey extension must not extend beyond the rear wall of the original house by more than:

3 metres for a terraced or semi-detached house

Rear extensions Time 0 01 0711 edited
Maximum depth for terraced or semi-detached

and 4 metres for a detached house.

Rear extensions Time 0 01 1212 edited
Max depth for detached house

The rear wall or walls of a house are those which are directly opposite the front of the house.

Rear extensions Time 0 01 1916 edited
Identifying the rear walls

The maximum depth is measured from the base of the rear wall of the original house to the outer edge of the wall of the extension (not including any guttering or barge boards).

Rear extensions Time 0 01 3322 edited
Measure depth from original house

With prior approval, a single-storey rear extension can be up to 6 metres long for a terraced or semi-detached house

Rear extensions Time 0 01 4408 edited
Max depth with prior approval, terraced or semi-detached house

and, up to 8 metres long for a detached house

Rear extensions Time 0 01 4629 edited
Max depth with prior approval, detached house

Note that prior approval for a longer rear extension is not available if the house is on Article 2(3) land or on a site of special scientific interest

Rear extensions Time 0 01 5315 edited
Prior approval not available on Article 2(3) land

Neighbour Consultation Scheme

Prior approval is achieved by engaging in a neighbour consultation scheme. Before the development is started, the local planning authority must receive:

  • a written description of the proposed development
  • a plan showing the
    • original house
    • any existing enlargement to which the enlarged part will be joined
    • and, the proposed development

The local planning authority must then give adjoining neighbours notice of the proposal and the opportunity to object. If anyone objects to the proposed development, then the local planning authority must assess “the impact of the proposed development on the amenity of any adjoining premises”.

If the Planning Office does not make a decision regarding the prior approval within 42 days, work may commence on the extension. If the Planning Office does make a decision regarding the prior approval within 42 days, it is likely to be one of the following, Prior Approval is:

  • Not required
  • Granted
  • Granted with conditions
  • Refused

With the first 2 decisions, work can commence. With the latter 2 decisions, you have the option to appeal.

Where a new extension is joined to an existing extension, the limits described above still apply. On a terraced or semi-detached house with prior approval, the maximum allowable depth is 4m.

Rear extensions Time 0 03 4924 2 edited
New extension joined to existing extension

With a pre-existing 3m rear extension, you can only extend a further 1m under PD rules.

Rear extensions Time 0 03 5210 1 edited
Pre-existing extension

On a detached house with prior approval, the maximum allowable depth is 8m. With a pre-existing 3m rear extension, you can extend a further 5m under PD rules.

Rear extensions Time 0 04 0726 edited
Pre-existing rear extension

Where the original rear wall of a house is stepped, then each of these walls will form ‘the rear wall of the original dwellinghouse’.

Rear extensions Time 0 04 2023 edited
Stepped rear wall

In such cases, the limits on extensions apply to any of the rear walls being extended beyond. On this example, a semi-detached house has an original ‘stepped’ rear elevation.

Rear extensions Time 0 04 3909 edited
Stepped rear elevation

If 3m extensions are added to each step, this complies with PD rules. In this example, the houseowner wants to extend the original ‘stepped’ rear elevation to achieve a continuous rear wall.

Rear extensions Time 0 04 4714 edited
Extending a stepped rear elevation

On the right, this part of the extension would be 9m long and so it cannot be achieved under PD rules

Rear extensions Time 0 04 5809 edited
Proposed rear extension not permissible

DOUBLE STOREY rear extension has the following limitations:

You are not allowed to build a double-storey rear extension on Article 2(3) land.

Rear extensions Time 0 05 2928 edited
double-storey rear extension not permitted

A double-storey rear extension has a maximum allowable depth of 3m on all types of houses (whether detached, semi-detached or terraced) There is no opportunity to extend further by prior approval.

Rear extensions Time 0 05 4516 edited
Max depth of rear extension

Where a new extension is joined to an existing extension, the 3m depth limit applies to the total enlargement. For example, this detached house has an existing, single storey, ground floor extension (not part of the original house) with a depth of 4 metres. It is not possible to add a first floor extension above this under PD rules as the total enlargement of the house would then consist of more than one storey and would extend beyond a rear wall by more than 3 metres.

Rear extensions Time 0 06 1728 edited
3m depth limit applies to total enlargement

A double-storey rear extension must be at least 7 metres away from any boundary of its curtilage which is opposite the rear wall of the house being enlarged.

Rear extensions Time 0 06 3824 edited
rear extension near boundary

This example does not comply with this limitation

Rear extensions Time 0 06 4308 edited
Rear extension encroaching on boundary

This example does comply.

Rear extensions Time 0 06 4724 edited
Rear extension complies with boundary condition

The extension roof pitch must be same as the original house roof pitch.

Rear extensions Time 0 06 5428 edited
extension roof pitch

Any upper-floor window situated in a side elevation of the dwellinghouse must be obscure-glazed to level 3 (One-way glass is not compliant)

Rear extensions Time 0 07 0023 edited
upper-floor window in side elevation

Also, the window should be non-opening unless the opening part is more than 1.7 metres above the floor of the room

Rear extensions Time 0 07 1514 edited
Window must be non-opening or 1.7m above floor

Where such a window is on a staircase or a landing (i.e. not in a room) the 1.7 metre measurement should be made from the stair or landing immediately below the centre of the window, upwards to the opening part.

Rear extensions Time 0 07 2126 edited
Side window on a staircase or landing

Thats it for this video

In the next one, video No 4, I’ll go through the rules for building side extensions under Permitted Development.

Rear extensions Time 0 07 4310
Rules for building Rear Extensions using Permitted Development 30