We live on a corner site, do I need planning to extend my sunroom?

I am considering a small (10sq m) expansion of an existing sunroom at the rear of my house. My question is whether the rear of the house is still considered the rear if it is a corner site, with one side of the house adjacent to a car-parking area for a small housing estate. Three of the units face my gable end wall, which is also my site perimeter wall.

Can I consider the rear extension as an exempted development, or should I play safe and go down the full planning route?

Val O'Brien writes: While planning permission is generally required for the development of property, there are planning exemptions for certain types of development and the most relevant exemption in this case relates to the construction of an extension to the rear of a house. In this respect, one can normally build an extension of up to 40sq m to the rear of the property and subject to other criteria including retaining a minimum of 25sq m of open space and complying with certain requirements regarding close proximity of windows to boundaries etc.

While the exemption clearly refers to an extension to the rear of the property, it does not distinguish between, say, a corner-style property as described here and a terraced property. Accordingly, in the normal course of events any exemption applying to the rear of a property would also apply in these circumstances.

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I note however that you are considering a small extension on to what appears to be an existing extension. Accordingly, you will need to ensure the combined floor areas of the extensions do not exceed the 40sq m, that you retain at least 25sq m of open space, and that you comply with all the other requirements in terms of positioning of the windows.

In addition to the above, you need to consider not only the planning exemptions but other issues that may have an impact on the situation. For example, normal planning exemptions do not apply in the case of a protected structure or if a property is located within an Architectural Conservation Area. Furthermore, you will also need to check any previous planning permissions, as very often a planning condition may have been imposed in an earlier permission preventing the normal exemptions; this is typical in high-density developments and/or corner properties such as yours.

Given the different potential scenarios I would advise you not just to rely on the normal planning exemption rules and to seek professional advice from a suitably qualified architect or chartered building surveyor. They will be able to carry out a full analysis and advise as to whether or not planning permission is required in your particular circumstances.

By doing this, your adviser will be able to clarify in advance what does and does not require planning permission and you can tailor the solution to fit within the exempted development provisions available to you, thereby avoiding the cost and time associated with going down the full planning route. Alternatively, you can make an informed decision about the merits of maximising your potential, albeit within your budget, which may well involve going down the planning route.

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