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Do I need planning permission for an attic conversion in Ireland?

Converting attic space for storage or a non-habitable use without altering the roof is generally exempted development, but adding a dormer window, roof extension or increasing the roof height to create habitable attic space usually requires planning permission, since these fall outside the standard exemptions.

Simply using existing attic space for storage, without any structural alteration to the roof, does not usually engage the planning system at all, since no development is taking place. Where structural works are involved, whether permission is needed depends on what is actually being built.

Small rooflights or Velux-type windows fitted flush with the existing roof slope can be exempted development under Class 8 of Schedule 2 to the Planning and Development Regulations 2001, subject to conditions on projection and location. A dormer window, however — which projects out from the roof slope to create standing headroom — is treated as a more significant alteration and normally requires planning permission, particularly on the front or side roof plane.

Where an attic conversion also creates a new habitable room, Building Regulations requirements around fire safety, means of escape, staircases and structural adequacy apply regardless of the planning position, and these are frequently the more demanding hurdle in practice.

What usually needs permission

Check whether your project involves any of the following, which typically require planning permission:

  • A dormer window or box dormer projecting from the roof slope
  • Raising or altering the ridge height or roof pitch
  • A rear dormer visible from a public road or amenity area (some limited exemptions can apply to rear dormers, subject to strict conditions)
  • Any works to a protected structure's roof
  • Increasing the overall floor area of the house through the roof alteration
  • Works that would exceed the 40 m² cumulative extension limit when combined with other extensions

Flush rooflights that do not project beyond the plane of the roof are the most common genuinely exempt attic works.

Building Regulations and structural checks

Even when planning permission is not required, an attic conversion must comply with Part B (fire safety), Part K (stairs) and structural loading requirements, and a structural engineer's assessment of the existing roof and floor joists is standard practice before work begins.

Sources

Last reviewed 20 August 2026. General information only — not legal or planning advice.

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