Appeal 3347628

The appeal is allowed and planning permission is granted for single storey side extension at [site address] , Hertfordshire [postcode] in accordance with the terms of the application, Ref 24/0679/FUL, and the plans submitted with it, subject to the conditions in the attached schedule.

Following submission of the appeal, the revised National Planning Policy Framework (the Framework) was published on 13 December 2024. The parts of the Framework most relevant to the appeal have not substantively changed from the previous version. As a result, I consider that there is no requirement for me to seek further submissions in respect of these matters, and I am satisfied that no party’s interests would be prejudiced by my taking this approach.

The main issues are: i) whether the proposal would be inappropriate development in the Green Belt; ii) the effect upon the openness of the Green Belt; and iii) if the development is inappropriate, whether the harm by reason of inappropriateness, and any other harm, is clearly outweighed by other considerations so as to amount to the very special circumstances necessary to justify development.

The appeal site comprises a single storey dwelling and detached double garage set within a spacious plot, which is situated within the Green Belt.

The Government attaches great importance to [name]. The fundamental aim of Green Belt policy is to prevent urban sprawl by keeping land permanently open; the essential characteristics of Green Belts are their openness and their permanence.

Policy CP11 of the Three Rivers District Council Core Strategy (CS) (2011) has a general presumption against inappropriate development that would not preserve the openness of the Green Belt, or which would conflict with the purpose of including land within it. Policy DM2 of the Three Rivers District Development Management Policies Local Development Document (TRDMP) (2013) and the Framework both set out that new buildings are inappropriate subject to certain exemptions. One such exemption relates to extensions to buildings that are not disproportionate additions over and above the size of the original building.

Neither the Framework nor the local plan define what is meant by disproportionate. However, the Council refer to Supplementary Planning Guidance (SPG) in which it is stated that extensions resulting in a cumulative increase in floor space of over 40% compared with the original dwelling may be disproportionate. Neither party has provided me with a copy of the SPG. Accordingly, an assessment of whether a proposal would amount to a disproportionate addition is a matter of planning judgement.

Whilst the property may have been previously extended, the evidence before me indicates the proposal would result in a cumulative 30% increase in footprint of the original dwelling, which is lower than the 40% referred to in the SPG. Having regard to the cumulative footprint, combined with the subordinate roof design, the proposed extension would not result in a disproportionate addition to the original building. I therefore conclude that the proposal would not be inappropriate development in the Green Belt. Accordingly, there would be no conflict with Policy CP11 of the CS, Policy DM2 of the TRDMP or the Framework.

[name] have found that the appeal development is not inappropriate development in the Green Belt, in line with the relevant exception in the Framework, no consideration of openness is required.

I have found that the appeal development is not inappropriate development in the Green Belt, in line with the Framework, it is not necessary to consider whether very special circumstances exist.

The proposed extension would be located within a relatively small gap between the northern flank wall of the dwelling and the northern boundary of the site, secluded by existing built form, including a detached garage. The extension would be well-related to existing built form and would not protrude into the lawn to the east of the dwelling. Accordingly, I do not concur that the proposal would result in a harmful spread of development across the site.

In addition to the statutory commencement condition, a condition is necessary to ensure that the development complies with the submitted plans in the interests of clarity. A condition for construction materials is included in the interests of character and appearance.

For the reasons given above, I conclude that the proposed extension would not result in disproportionate additions over and above the size of the original dwelling and is therefore not inappropriate development in the Green Belt. The proposal accords with the development plan and Framework. Having had regard to all matters raised, I conclude that the appeal should be allowed.

The development hereby permitted shall begin not later than three years from the date of this permission.

The development hereby permitted shall be carried out in accordance with the following approved plans: TRDC-01 (Location Plan), 727-01 A, 727-02 A, 727-03 C

Unless specified on the approved plans, all new works or making good to the retained fabric shall be finished to match in size, colour, texture, and profile those of the existing building. ***End of Schedule***