Detached Garage Planning Permission - Northern Ireland
Do I need Planning permission or Building Control approvals?
To help you understand these issues we detail below some of the "conditions" attached to planning permission and Building Regulations. (These apply to Northern Ireland only) Wales Scotland, England, Ireland regulations are quite different - You should in all instances take local advice.
Do I need permission for a Detached Garage?
According to "Your Home and Planning Permission" - A Guide for House Holders in Northern Ireland a detached garage within 5 meters of the house will be treated as an extension and Rules A - F will apply.
A detached garage more than 5 meters from the house will be considered under the Rules L - O.
Below we detail the main points with regards to planning permission for a detached garage in Northern Ireland.
Do I need permission to build a detached garage within 5 meters of the house.
No, where the proposed extension complies with Rules A - F below
A garage in a Conservation Area or within 5 meters of your house will be treated as an extension to the house.
Rule A. The size of the garage must not be more than:
-Terraced house: 50 cubic metres or 10% of the original house volume, whichever is the greater
-Any houses in a Conservation Area: 50 cubic metres or 10% of the original house volume, whichever is the greater
-Any other house (detached or semi-detached): 70 cubic metres or 15% of the original house volume, whichever is the greater.
Illustration 1: Building an extension (Note 2 and Note 3)
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Three identical extensions but only the extension at house 'A' would not require planning permission. At house 'C', the existing garage was added after 1 October 1973 and is therefore treated as an extension. The volume of the garage (44m3) plus the proposed extension (30m2) would exceed the stated allowance (70m3) and so planning permission would be required.
At house 'B', planning permission would be required because the extension would be within 5 metres of an existing building belonging to the house, causing that building to be treated as if it were part of the extension. The combined volume again exceeds the stated allowance.
Finally, at house 'A', the existing garage would not be treated as an extension as it would remain beyond 5 metres from the house and the proposed extension.
Rule B. The design and materials to be used to build the proposed extension must be in keeping with the main house.
Rule C. No part of the extension should be nearer to any road than the part of the original house nearest to the road.
Rule D. No part of the extension should be higher than the highest part of the existing roof of the house.
Rule E. The extension should not be more than 4 metres high if it comes within 3 metres of the boundary of the property (see Illustration 2). Height is to be measured from ground level, measuring the level of the surface of the ground immediately adjacent to the building or if it is not uniform, the level at its highest adjacent part.
Rule F. The ground area covered by the extension and any other buildings within the boundary of the property (excluding the original house) must not be more than half the total area (not counting the ground area of the original house).
Illustration 2: Building an extension (Rule E)
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Note 1: In all cases size is calculated from external measurement, and there is an upper limit of 115 cubic metres.
Note 2: Any extension built since 1 October 1973 will not be treated as part of the original house volume. It will therefore be necessary to subtract the volume of any existing extension from the allowances specified above. The amount left over (if any) is the amount, which you can extend without planning permission providing the proposed addition also complies with Rules B to F (see Illustration 1).
Note 3: In some cases other buildings on your property will be treated as extensions and will reduce the allowances for extending your house.
If an extension to your home comes within 5 metres of another building belonging to the house (e.g. garage, shed or greenhouse, etc) that building will be treated as if it were part of the extension (see Illustration 1).
Any building added to your property which is more than 10 cubic metres in volume and which is within 5 metres of your house is treated as an extension and so reduces the allowances for further additions to the house without planning permission (see Illustration 3).
If you live in a house which is a listed building of is in a Conservation Area, all additional buildings which are more than 10 cubic metres in volume, regardless of the distance from your house, are treated as extensions and reduce the allowance for extending without planning permission.
Note 4: The figures given for maximum sizes in Rule A represent the total amounts which can be built without planning permission. If, for example, you are making an addition to the roof of your house and also extending the house. The volume of both structures added together must not exceed the relevant amount shown at Rule A. Note 5: If you live in a house, which is a listed building, it is likely that you will need Listed Building Consent for the building operations covered in this report. Your local planning office will advise if such consent is required.
Illustration 3: Building an Extension (Note 3)
Do I need permission to build a detached garage more than 5 meters from the house.
You do not need planning permission if the garage is more than 5 metres from your house, unless you live in a listed building. You must, however, comply with Rules L - O.
Rule L. The garage must be used for domestic purposes only.
Rule M. No part of the garage should be nearer to any road than the part of the original house nearest to the road.
Rule N. The height of the garage must not be more than 4 metres high if it has a ridged roof, or 3 metres in any other case.
Rule O. The ground area covered by the garage and any other buildings within the boundary of the property (excluding the original house) must not be more than half the total area.
The garages at houses ‘A’ and ‘D’ would require planning permission as they would be closer to the road than the part of the original house closest to the road. The garages at ‘B’ and ‘C’ would not require planning permission provided they complied with all the relevant Rules.
If the work you are carrying out involves making a new access, or the alteration of an existing access to a trunk or classified road, you will need planning permission.
BUILDING REGULATIONS - Northern Ireland
Domestic single storey detached garage up to 30 sq meters are exempted under Building Regulations (Northern Ireland) 2000, the rules are listed below.
A detached single storey building, having a floor area which does not exceed 30 m2, which contains no sleeping accommodation and is a building which is either -
All garages built of brick or block walls and have a tiled roof are considered to be substantially of non-combustible material. Flat roof garages can also be substantially of non-combustible material when the roof is covered with 12.5mm limestone chippings. | 
