How much does an attic conversion cost in Ireland in 2026?

As an indicative 2026 range, a rooflight (Velux-type) attic conversion costs around €25,000–€40,000, while a dormer conversion runs €40,000–€60,000 or more. Simple storage-only boarding and lighting costs far less. Stairs, fire-safety compliance and insulation all add to the figure. Always get at least three written quotes.

What's the difference between a rooflight and a dormer attic conversion?

A rooflight conversion keeps the existing roof shape and adds Velux-style windows in the slope — cheaper and often exempt from planning. A dormer adds a box-like projection out from the roof to create more headroom and floor space, which costs more and usually needs planning permission.

Does an attic conversion need planning permission in Ireland?

A straightforward rooflight conversion within the existing roof is often exempt, but dormers, changes to the roof profile and converting the attic into a habitable room can require planning permission and must meet Building Regulations for headroom, stairs and fire safety. Confirm with your local authority before starting.

Can I convert my attic into a bedroom?

Only if it meets the standards for a habitable room — adequate headroom, a compliant fixed staircase, fire-safety measures and proper insulation and ventilation. Many attic conversions are legally classed as non-habitable storage or hobby rooms unless these standards are met. An architect or engineer can advise on your specific roof.

Attic Conversion Cost Ireland 2026 (Rooflight vs Dormer)

An attic conversion in Ireland costs roughly €25,000–€40,000 for a rooflight (Velux-type) conversion and €40,000–€60,000+ for a dormer (indicative 2026 ranges). Storage-only boarding costs a fraction of that. The big variables are the conversion type, stairs and the fire-safety work needed to make the room habitable.

Attic conversion cost by type

Type	What you get	Indicative 2026 cost
Storage boarding	Floor boarding, light, loft ladder, basic insulation	Much less — often a few thousand euro
Rooflight conversion	Existing roof shape, Velux windows, floor, stairs, insulation, finishes	€25,000–€40,000
Dormer conversion	Dormer projection for headroom and space, plus all of the above	€40,000–€60,000+

Habitable vs storage

This distinction matters legally and financially. A storage/hobby room has lower requirements and costs less. A habitable room — a bedroom or office you’d genuinely live in — must meet Building Regulations: sufficient headroom over a defined floor area, a compliant fixed staircase (not a loft ladder), fire-safety measures (often fire doors on the floors below, mains-wired interlinked alarms, and a protected escape route), and proper insulation and ventilation.

If your conversion can’t meet the headroom standard within the existing roof, a dormer is usually the way to gain it — which is the main reason dormers cost more.

What’s included

Structural work — strengthening joists to take floor loads.
Stairs — a fixed staircase, which can eat into the room below.
Rooflights or dormer construction.
Insulation of the roof to current standards.
Fire-safety compliance — doors, alarms, escape route.
Electrics, heating and plumbing (if adding an en-suite).
Plastering, flooring and decoration.

What affects the price

Rooflight vs dormer — the single biggest cost factor.
Stairs. Fitting a compliant staircase can require reworking the landing below.
Fire compliance. Upgrading doors and alarms across the house adds cost.
En-suite. Adding a bathroom means plumbing and waterproofing.
Roof structure. Cut roofs are easier to convert than trussed roofs, which need structural changes.
Headroom. Tight headroom may force a dormer or rule out habitable use.

Tie in the attic insulation grant

While the attic is open is the ideal time to insulate the roof properly, and SEAI grants are available for attic insulation. See our insulation grants guide for what’s available and how it works, and our attic insulation guide for the practical detail. Note that grant-supported attic insulation has its own technical requirements, so coordinate this with your builder early. Insulating well during the conversion improves comfort and your BER rating at the same time.

Ways to save

Choose a rooflight conversion if your headroom allows — it avoids dormer construction and often avoids planning.
Plan the stairs early to minimise the space lost on the floor below.
Combine the insulation with grant support while the roof is open.
Skip the en-suite if budget is tight — it’s the most expensive optional extra.
Get at least three written quotes, each clearly stating whether the room will be certified as habitable.

Build in a contingency for surprises in the roof structure, and get written confirmation of whether your conversion meets habitable-room standards before you commit.