Do I need planning permission to convert our attic?

Property Clinic: We want to do an attic conversion, but it will mean raising the roof on one side

Attic space in a newly built house, ready for conversion.

Attic space in a newly built house, ready for conversion.

 

My sister bought a house and as we are a family of five in the house, three bedrooms is not enough. I work in the construction industry as a scaffolder and I have contacts for reliable workers. We would like to make an attic conversion, but to make it liveable we want to raise one side of the roof.
How can I do this? Who do I need to contact? Where and how do I obtain the planning permission? What paper work needs to be filled in for this to go ahead?

Converting an attic is a very useful and relatively economic way of creating additional accommodation in a house. This can very often be done without the need for third-party approvals such as planning permission. If the works are largely internal and do not interfere with the overall external appearance of the house, apart from the provision of Velux-style roof lights within the rear roof slope which constitutes exempted development, this does not require planning permission.

However, if it is your intention to raise the height of the roof in, say, a dormer-style extension, then this will materially alter the appearance of the house and planning permission will be required. The only disadvantage of planning permission is that it takes time – minimum three months – and this will inevitably give rise to some additional costs. However, I would not necessarily steer you away from this, as you would ultimately end up with a better/ larger and more useful room by virtue of raising the roof.

Structural implications

It is particularly important to consider the structural implications of converting a roof. Most roofs are triangular and this is perhaps the simplest and best possible structure. Altering this is more significant than one might think, particularly if converting a prefabricated trussed roof, which is fairly typical for most housing estates built within the past 40 years. Truss roofs tended to have the minimum amount of timber but also provided a very efficient structure. By way of example, consider removing some spokes from a bicycle wheel and expect that the bike will perform as well in its converted state as it would have done prior to conversion.

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Accordingly, it is particularly important that you get advice from an appropriate consultant such as a structural engineer before undertaking the conversion works. For the benefit of other readers, I am afraid to have to point out that there are many “dodgy” attic conversions around which are unlikely to meet the appropriate structural requirements, that would be expected of a roof in times of unusual or abnormal storm conditions.

Type of room

Perhaps the most important issue of all to consider is the type of room which is being created as a result of the attic conversion. If you want to achieve the status of a “habitable room” ie a living room or a bedroom, then there are a significant number of obligations to be met in order to comply with the relevant building regulations such as a minimum head height of 2.4m over two-thirds of the floor area of the room, a minimum 800mm wide staircase not exceeding a 42 degree pitch and with a clear minimum head height of 2 metres.

More significantly, one needs to consider the means of escape from the room in the event of a fire. In this respect, I would point out that the majority of houses in Ireland are either single or two-storey houses, and the regulations applicable to these houses are quite modest.

Fire regulations

However, a three-storey house brings you into a different category and a whole host of new regulations which need to be met from a fire escape point of view. If converting an attic in a typical two-storey house to a proper “habitable room”, there is an obligation to ensure a safe means of escape from the room in the event of a fire and this would involve having to upgrade the fire-resistant standard to the staircase at both ground and first floor level; to include upgrading the enclosing walls to one-hour fire-resistant construction and upgrading the doors to half-hour fire-resistant construction complete with self-closing devices. This can be fairly disruptive on the existing house and will give rise to considerable additional cost.

While the regulations are very well intentioned and are there to ensure a minimum quantity of construction, the difficulty posed by the restrictions of the existing house very often means that most “attic conversions” are considered as non-habitable or storage rooms. Before you commit to undertaking an attic conversion, you do need to be fully aware of all the implications of what you are taking on and what you will end up with and, in this respect, it is important to get professional advice. A chartered building surveyor should be more than happy to guide you through the process.

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

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