Appeal 3355407

The appeal is allowed and planning permission is granted for extension to existing garage at [site address] , [site address] , [site address] , [postcode] in accordance with the terms of the application, Ref 6/2024/1407/HOUSE, subject to the following

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

The development hereby permitted shall be carried out in accordance with drawing nos H-PL-01 Location and Site Plan, H-PL-02 [name] and Roof Plan, H-PL-04 [name], H-PL-05 [name] and Elevations and H-PL-03 [name].

The external materials of the extension hereby permitted shall match those used in the existing building.

The National Planning Policy Framework (the Framework) was updated in December 2024, during the consideration of this appeal. Insofar as is directly relevant to the appeal, there are no substantive changes and no parties have been prejudiced as a result.

The main issue is whether the proposal would be inappropriate development in the Green Belt having regard to the Framework and any relevant development plan policies.

The appeal site consists of an existing garage associated with the residential property at No [site address] . The property at No 1 is a [name]* listed building1 with substantial grounds and a vehicular access from [site address] . The Garden 1 National Heritage List for England Entry Number: 1100972. Walls at [address] are also a Grade II Listed Building2. The site is also located in an Unregistered Historic Park and Garden.

The property is washed over by the Metropolitan Green Belt. Paragraph 142 of the Framework is clear that the Government attaches great importance to Green Belts and sets out that 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.

The proposal is for the extension of the garage to enlarge the spaces within it, making them more practical for use for the parking of vehicles. The proposal also includes additional bathroom facilities at ground floor level for use by the gardener/visitors. At first-floor level the proposal would provide an increase in the existing storage space and occasional overnight family accommodation. The proposed extension would be finished in matching external materials and would introduce half-hips to the existing roof.

Paragraph 153 of the Framework identifies that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. Paragraph 154 states that development in the Green Belt should be regarded as inappropriate, save for a limited number of exceptions. The exceptions include, under paragraph 154 c), the extension or alteration of a building provided that it does not result in disproportionate additions over and above the size of the original building.

Policy SADM 34 of the Welwyn Hatfield Borough Council Local Plan 2016 – 2036, October 2023 (LP) echoes this, stating that applicants will need to demonstrate that extensions and alterations to a building would not result, either individually or cumulatively, in disproportionate additions over and above the size of the original building, in terms of bulk, scale, height or massing. The Policy goes on to say that account will be taken of the extent to which the extension and/or alteration would be consistent with the general pattern of development and character of the area and its prominence within the landscape.

The supporting text to this policy is clear that both a quantitative and qualitative assessment will be undertaken. In quantitative terms the Council set out that proposals that would result in the footprint, volume and/or above ground external dimensions of a building being 50% greater than the original building would be generally refused. The supporting text, however, goes on to say that each case will be assessed on its own merits and there may be circumstances where an increase in excess of 50% would be acceptable (or indeed where a smaller percentage increase would be required).

The starting point for determining whether the extension or alteration of the building would result in disproportionate additions over and above the size of the original building must be to identify the original building. In respect of this appeal, the evidence before me demonstrates a varied approach.

The term ‘original building’ is defined within the Glossary to the Framework as a building as it existed on 1 July 1948 or, if constructed after 1 July 1948, as it was 2 National Heritage List for England Entry Number: 1100973. built originally. The garage which is proposed to be extended was constructed following the grant of planning permission in 20113 and subsequent non-material amendments in 2012 and is therefore considered by the appellant to represent the original building in this case.

The plans before me indicate that the proposed garage would maintain a depth of around 6 metres but would have a marginally raised ridge height. The length of the building would be extended by approximately 2.6 metres. The plans indicate that the resultant building would not be 50% larger than the existing building. The plans also demonstrate that the stairs to the, newly enlarged, first floor would be moved from their current location and a large window with external sliding louvre shutters would be added at first-floor level.

I accept that no first floor was shown on previously approved plans, albeit that a subsequent application for rooflights was approved. Nevertheless, a first floor currently exists. Whether or not the installation of the first floor required planning permission is not a matter for me to consider as part of this appeal.

Even if the additional space at first-floor level were included and the proposal was, consequently, considered to represent an extension which would exceed the percentage threshold, this test is caveated and it is clear that it forms only a part of the assessment to be carried out.

When considered qualitatively, I consider that the proposed extension would sit comfortably with the building as a whole and would not be an overly large or out of scale addition. The resultant building would retain its relatively small scale and the use of a half-hipped roof form would assist in minimising the visual impact of the building. The installation of the large window to the garden elevation would make activity at first-floor level more visually apparent. This, however, would be the case only when viewing the building from specific and limited viewpoints of that one elevation. Moreover, the existence of activity at first-floor level would not increase the perceived bulk of the extension.

In my view, when considered in the context of the garage as a whole, the additional length and height would represent a reasonably sized addition which would be proportionate to the scale and massing of the building.

Notwithstanding the above, the supporting text to Policy SADM 34 states that proposals to erect, extend or replace an incidental building within 5 metres of the main building will be treated as an extension to the main building. The evidence before me appears to indicate that at the time of permitting the garage it was considered on the basis that it was an extension to the original building and not a new building in its own right. Indeed, the detached garage which is proposed to be extended is situated close to the main dwelling and there is a clear functional relationship between the two such that the garage represents a normal domestic adjunct.

[address] has an extensive planning history and many changes have occurred over time. Though the evidence is by no means conclusive it is certainly clear that the original building stood on a much larger site which has since been redeveloped through the subdivision of the site and the erection of additional properties. The evidence before me is limited and there are no definitive 3 Reference S6/2010/3095/MA and S6/2012/1373/NM calculations before me regarding the total increase in built form over the original building or specific, detailed information about the scale, or massing of any previous extension. As such when attempting quantitative calculations the evidence before me contains a number of uncertainties and is not such that a clear conclusion is easily reached with any great degree of confidence.

However, as set out above, the Council’s policy is also clear that a qualitative assessment will form a key part of any consideration regarding whether any extension would be disproportionate.

Whilst the preceding paragraphs explore the extension through the lens that the garage itself is considered the original building, the same reasoning applies when considering the alterations to the garage building as further extensions to the wider building and site.

The garage, as extended, would remain a reasonably small building. The wider appeal site, and the main building, are undisputably large. The host dwelling is an impressive and visually dominant building set within spacious grounds. The garage, as extended, would sit comfortably as a subordinate structure to the main building. The garage would appear as a reasonably discreet building which would not be of a bulk, scale or massing so as to appear at all incongruous or overly large within its setting. Due to the scale of the appeal site and the main building within it, even when considered cumulatively, past extensions to the property in combination with the extended garage would not appear as disproportionate additions. The proposed extended garage building would be consistent with the pattern of development and character of the area and would not appear as a prominent feature within the landscape.

Accordingly, irrespective of which structure is considered to be the original building for these purposes and even if the proposed extension was considered to result in an increase in the size of the original building of more than 50%, based on the considerations set out in Policy SADM 34 of the Local Plan, the evidence before me and my observations on site, it would not be a disproportionate addition over and above the size of the original building. It would therefore not constitute inappropriate development in the Green Belt. It would accord with Policy SADM 34 of the LP and the associated provisions of the Framework, which seek to protect the Green Belt from inappropriate development. Given the proposed extension would not be inappropriate development, in this case, there is no need for me to consider its impact on openness.

As set out above, the garage which is the subject of this appeal is an ancillary building serving a [name]* listed building. The nearby [name] at [address] are also [name] listed. Mindful of the statutory duty set out in s66(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990, I have had special regard to the desirability of preserving the settings of the listed buildings. The appeal site is also situated within the Unregistered Historic Park and Garden of [address].

[address] dates from around 1690 but has evolved over time. The garden walls date from around the same period. Their special interest and significance primarily stem from their historic and architectural interests and group value. However, they are also derived, in part, from their formal and largely open and verdant settings, which includes the appeal site.

The proposal is for minor works to slightly extend the size of the existing garage. Given the position and nature of the proposed development, I find that the settings of these listed buildings would be preserved. The significance of the designated heritage assets would not be harmed. I note that this view is in conformity with that of the Council as they did not express concerns in this regard.

In respect of the Unregistered Historic Park and Garden, I note the comments made by the Gardens Trust in respect of the potential for the first-floor window to introduce glare which would affect views of the landscape. However, this window is in a reasonably discreet location, is not overly large, and includes louvered shutters. As the garage is in close proximity to the larger house which has its own expanse of windows, I do not consider that the addition of this window is such that it leads to the requirement for further intervention such as increased planting or screening in this regard. In my view, the proposal would preserve the significance on the non-designated heritage asset.

The National Planning Policy Framework makes clear that planning conditions should be kept to a minimum, and only used where they satisfy the following tests: necessary, relevant to planning, relevant to the development to be permitted, enforceable, precise and reasonable in all other respects.

Alongside the standard time limit condition, I have imposed a condition specifying the relevant plans as this provides certainty. Due to the sensitive nature of the location, In order to safeguard the character and appearance of the area I have included a condition requiring matching materials.

For the reasons set out above, and having regard to all other matters raised, I allow the appeal