‘I want to build an eco granny flat in my friend’s garden. Will I get permission?’

Property Clinic: ‘I hope to build it at the back of the garden, about 30ft from the house’

‘The granny flat would be one storey, with loads of ground space around the site.’ Photograph: Getty Images/iStockphoto
‘The granny flat would be one storey, with loads of ground space around the site.’ Photograph: Getty Images/iStockphoto

I am planning on building a granny flat in a friend’s back garden (30ft by 27ft in total area). It would be an A1-rated eco-house in the Shankill area. I hope to build about 30ft from the main house, ie down her back garden, and the flat would not be seen from the roadway. It would be one storey, with loads of ground space around the site. I hope to attach this flat to the main building by a wall from gable to gable – and maybe build a walkway.

Would I get planning permission for a 30ft wall attachment between the two buildings only? It is VERY awkward to attach the flat to a wall of the main house. The flat would have one separate entrance only.

There is no clear-cut answer as to whether or not you would get planning permission and the only way you will know is if you go through the planning process. However, clearly it is possible to seek some guidance as to the likelihood of a positive decision before going to the trouble and expense of making a planning application.

It is clear that a development of this size and nature requires planning permission. Whilst the principle of “granny flats” are permissible, this often comes with restrictions including conditions such as “must be connected to the main house” or “must be used by a family member or as an ancillary use and not to be separately let or sold off”. Sometimes the planning can restrict the permission by limiting it to a “life” such as say five years, in which case a further application would have to be made in five years’ time in order to continue with the development/use.

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Relented

Whilst I do not know the site, I can advise that the planners would not be favourably disposed to a separate detached and independent house in the back garden and are only likely to consider something which would be “ancillary to the main dwelling”.

This is because they do not want to set a precedent of creating a new house. If the planners relented on this, then others would also possibly look for a second house in their back gardens and could end up virtually doubling the number of houses in an estate/area with significant impact on the infrastructure within an area including public drains, utility services, roadways and indeed public transport.

Accordingly it is my view that the chances of a successful planning permission here will be minimal. However as I do not know the site you should consider seeking a further specialist opinion on this. A further option to consider is to seek a pre-planning consultation with the planner and to bring a site plan together with drawings of the proposed eco-house. This way you might get a preliminary view from the planner as to the likelihood of getting a successful planning, and they may be able to give you a fair indication of the likely chances of success at such a meeting.

Val O'Brien is a chartered building surveyor and member of the Society of Chartered Surveyors Ireland, scsi.ie