Can my neighbours build their extension roof higher than my extension roof if they are side by side with a narrow gap in between?
Val O'Brien writes: There are two broad categories which need to be reviewed, namely works which one can undertake without the need for planning permission, ie, exempted development, and works for which planning permission is required.
Perhaps it is simpler to deal with the second category first in that to some extent an applicant can seek permission for whatever they want, and it is up to the planning authority to review the proposal and if it is deemed to be appropriate and in keeping with the character/style of the properties, then it is most likely that permission will be granted.
During the planning process, third parties have the opportunity to make observations in respect of any planning applications and to object if they believe it will have a negative impact on their own property. There are strict requirements in terms of timing when it comes to making an observation or an objection on a planning application.
If your extension is single-storey to the rear of a two-storey house, then there is nothing that prevents your neighbour from building their extension higher than yours
However, I expect that your query is likely to be a more typical one in the context of exempted development – where a neighbour is entitled to build an extension to the rear of their property without seeking planning permission.
The reason for exempted development is to assist the public in making modifications to their properties without having to “clog up” the planning system with applications which would be considered straightforward and not to have a material impact on the property or its surrounding environment.
There are many categories of exempted development. The relevant category relating to an extension to the rear of a dwelling house is covered under Schedule 2, Part 1, Class 1 of the Planning and Development Acts. This sets out the parameters for exempted development which allow one to build an extension to the rear of a property provided that it does not exceed 40sq, m in total, taking account of any other previous extensions to the property.
Up to 12sq m of such an extension is permitted at first-floor level in the case of a semi-detached or terraced house and up to 20sq m in the case of a detached house. There are however further restrictions in terms of the distance between the side wall of an extension above ground-floor level and a neighbouring property, but there are no such restrictions in respect of a wall at ground-floor level.
There are also restrictions in terms of location and distance of windows from a boundary wall and a requirement to retain a minimum of 25sq m of open space to the rear of the property. The height of the new extension must not exceed the height of the rear wall of the property.
Notwithstanding the restrictions, exemptions are quite generous and allow the construction of fairly substantial extensions to the rear of a property without the need for planning permission.
So, in considering your query about the height of the neighbour’s extension exceeding the height of your roof, and the proximity of same, if your extension is a single-storey extension to the rear of a two-storey house, then there is nothing that prevents your neighbour from building their extension higher than yours and tight up against the boundary wall.
For the avoidance of doubt, neither exempted development nor a grant of planning permission would permit a neighbour from interfering with or “over sailing” a boundary wall and thus the neighbour will have to keep within the confines of their own boundaries.
There is nothing to prevent two parties coming to an agreement on having a shared wall on the party line to the mutual benefit of both parties for future extensions.
I would also caution that while planning exemptions permit extensions, this is not a carte blanche exemption as there are cases when exemptions do not apply as in the case of a protected structure or where there may have been planning conditions imposed on a master/original planning permission.
Anyone considering undertaking exempted development may need to seek advice to ensure that they are operating fully within the exempted provisions.
Val O’Brien is a chartered building surveyor and member of the Society of Chartered Surveyors Ireland, scsi.ie
