Casebook: Development Control Casebook Forum

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Alternatively, post them to Development Control Casebook Forum, Development Control Services Ltd, Suite 1, Fullers Court, 40 Lower Quay Street, Gloucester GL1 2LW or fax them to 01978 869355.

New queries

I received a telephone call from the officer dealing with my application for a house extension requesting that it be reduced in size. However, before negotiations could take place permission was granted with a condition requiring that amended plans be submitted and approved showing the extension reduced in size by a specified amount. Is this acceptable? JA.

Circular 11/95 explains that a condition modifying development cannot be imposed if it would make the development substantially different from that proposed by the applicant.

Whether a modification would amount to a substantial difference will depend on the circumstances of the case. But the circular points out that a useful test is whether it would so change the proposal that those interested in it would wish to comment on the modification.

It is not normal practice for proposed house extensions to be altered in this way. It could be argued that the condition is unreasonable because it takes away much of the benefit of the permission. You may therefore wish to consider an appeal.

A 13m mobile home on wheels has been stationed in a garden more than 5m from the house. It includes a living room, bedroom, bathroom and kitchen and is connected to mains power and drains. The unit is occupied by the householder's mother. It is claimed that it is used as ancillary accommodation with the mother spending the day in the house. My authority considers the mobile home a self-contained unit of accommodation that requires permission.

The householder disagrees, citing Whitehead v Secretary of State and Mole Valley District Council (1991). What is your advice?

The mobile home appears to be a caravan that has not involved operational development. The use of a caravan in a residential curtilage for "purposes incidental to the enjoyment of the dwellinghouse as such" falls within the primary use of the dwelling, so it is excluded from the definition of development.

The term "incidental" is not defined in planning law. But Whitehead intimated that semi-independent housekeeper's accommodation in a barn within a dwelling's curtilage could be incidental to its enjoyment and thus permission was not required.

In Uttlesford District Council v Secretary of State for the Environment and White (1992), it was held that the conversion of a garage in a residential curtilage to a granny annexe had not resulted in a material change of use, despite it including facilities that enabled the occupier to live independently.

The general approach of the courts is that it is the actual use of a caravan that is determinative rather than its potential to be occupied as a self-contained residential unit. So permission may not be required for the mobile home.

I wish to redevelop a dwelling on a sizeable plot between existing housing in the green belt, which was designated after the homes were built. The planning authority is seeking to limit the size of the replacement home even though this would not affect the statutory purposes for green belt designation. Are there any precedents for this and have there been any successful appeals against such "planning by policy" rather than sensible appraisal of the proposal's merit? Has there been a test on human rights legislation?

PPG2 advises that replacement dwellings are not inappropriate provided they are not materially larger than those they replace. It adds that development plans should make clear the approach planning authorities will take, including the circumstances, if any, under which replacement dwellings are acceptable.

Typically, local planning policies will only tolerate an increase in size of up to 25 per cent of the original dwelling's floor space. However, the pragmatic response to most rural replacement house proposals is to note appropriate plan policy and to assess a proposed replacement for any increased impact on the countryside, green belt openness or other interests.

Sometimes larger dwellings may be found to be less harmful than the houses they replace. Various decisions where inspectors have allowed appeals despite replacement dwellings exceeding policy limits are outlined in Development Control Practice 9.631. It is rare for arguments on human rights to succeed and I can find no relevant case.

Previous queries

In reply to a query from MW (Planning, 17 November, p41) about a house and extension subject to separate permissions in 1973 but built in a single operation, PM stated that the extension would comprise part of the "original dwellinghouse".

- While I agree with PM's advice, if the foundations and walls are continuous they must have been built at the same time. Therefore, although they are now immune from action, both the dwelling and the extension must be unauthorised.

Permission cannot be granted for an extension to a building that does not exist.

If the house were built at the same time as the extension, the resulting building is not the house that had been permitted. The obvious solution would have been to have applied to build a different house type - the one with the extension. The applicants could then choose which house they built. This would also be the cheaper option because no fee is payable for the resubmission.

I often encourage major house builders to apply for an estate of houses with conservatories, which are then optional extras, depending on customer demand. While this makes no difference to MW's query, it does raise an issue that many practising in development control must come across. Your views would be helpful.

- I agree that planning permission should not be granted to extend a dwelling that has not yet been built. However, where separate permissions have been granted for a new house and for its extension before it is completed, it seems perverse and of little relevance to regard the built structure as being unauthorised.

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