How do I turn a granny flat into a separate dwelling and keep the council happy?

What are the private open space requirements that would allow an existing granny flat to be converted into a separate dwelling that would satisfy Dublin City Council? Can the area of the side entrance be included in the arithmetic?

We have contacted Dublin City Council but we are still not sure as we cannot get a clear answer from them. They keep referring us to the Dublin City development plan.

We think we are okay on parking and have separate drainage for the granny flat. Electricity and water can be solved easily enough. Our last child is in the process of vacating the granny flat after it has been in use continuously for the last 11 years.

At the outset, you should be aware that the Dublin City Development Plan (2016-2022) sets out policies and objectives to guide how and where development will take place in the city. In your particular case, the site will be governed by the land use zoning “sustainable residential neighbourhoods”, which has a specific objective “to protect, provide and improve residential amenities”.

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You have been guided correctly by the council to check their particular planning requirements and standards within the development plan. I would guide you to chapter 5 (quality housing) and chapter 16 (development standards), which outlines specifics regarding design, layout, etc. The development plan also requires that the amenities of adjoining properties are protected, in particular the need for light and privacy. This will also extend to ensuring the character of existing buildings is maintained.

It is unclear if the existing granny flat is of an adequate size to function as an independent home (ie sufficient floor space to have it internally remodelled) or if you intend to extend/ demolish this. I expect that the existing development is compliant with relevant planning and building control requirements. If an existing permission is in place, you should refer to planning conditions that may restrict its use.

Default permission

Be mindful that if your existing home/extension is not covered under “exempted development” (planning regulations) or does not have the required permission, then you will be required to regularise matters by seeking “retention” permission. The fact that the accommodation has been in use continuously for 11 years (as you reference) will not mean that you have a default permission. Any future purchaser (and mortgage provider) will require written confirmation that all planning/building control requirements have been satisfied.

Privacy is considered an important element of residential amenity. In this regard, the council’s standard for “private open space” allows for space to be provided by way of private gardens at the rear/side of a house. A minimum standard of 10sq m is required per bed space (single bed), with a reduced requirement applicable within the inner-city area. Rear gardens and private space must also be screened from public areas.

There are two particular development controls relevant to your specific query for private open space – “plot ratio” and “site coverage”. The requirements may be relaxed in the case of a property being developed close to major public transport termini, urban renewal areas, etc.

You are correct that any shared services will require separate connection to the mains (water, waste water, surface water and utilities). I note that you advise that these can be provided. You have not indicated if you intend to have a separate road/footpath access and this will be guided by the particular location and associated sightlines.

Suitably qualified professional

I would strongly recommend that you now engage the services of a suitably qualified professional (eg building surveyor, architect, etc) for advice and I expect your agent might seek a pre-planning meeting with the council’s planning department to discuss your proposal . If your property is listed on the council’s record of protected structures or located within an architectural conservation area, additional requirements will apply.

Andrew O’Gorman is a chartered building surveyor and member of the Society of Chartered Surveyors Ireland, www.scsi.ie