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Attic Conversion Calculator
See what your renovation could cost in 2026, with real Dublin and national pricing. Get an instant estimate, full house or room by room.
Pre-1970 properties carry a higher recommended contingency
Usable floor area after conversion, not total roof footprint
Add-ons
On planning permission: whether it's required depends on the specific design, location and works involved, not simply the conversion type — recent changes to exemption rules mean some rear and side dormers may now qualify as exempted development subject to conditions. The add-on above is an estimated allowance for drawings, applications and professional fees; turn it on if your project is likely to need it.
estimated construction cost
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select options above
add-ons selected
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en suite, staircase, structural, planning
contingency
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recommended reserve, not part of build cost
suggested maximum budget
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build + add-ons + contingency
Select your conversion type, floor area and options above to see your estimate.
Cost breakdown
Property value: according to the SCSI House Extension and Conversion Report, a professionally completed attic conversion adds approximately 12–15% to a property's value in Dublin, one of the highest-return home improvements available.
These figures are estimates for planning purposes only, including VAT at 13.5% on qualifying construction services (the VAT treatment of certain separately supplied goods or materials may differ). A written quote from a contractor who has visited your property is the only accurate figure. Attic conversions carry large fixed costs — structural engineering, staircase, fire protection and services — so a small conversion is not simply a fraction of the price of a larger one, which is why floor area adjusts the estimate rather than multiplying it directly.
How this price calculator works
This calculator uses build cost ranges compiled from Build Me project data and current 2026 Irish market rates across four loft conversion types: rooflight, dormer, hip-to-gable and mansard. Figures include labour, materials and VAT at 13.5%.
Dublin rates run 10 to 15% above the national average, which is reflected in the location toggle, and contingency automatically adjusts to 20% for pre-1970 properties, where hidden structural issues are more common once the roof is opened up.
The planning permission toggle defaults based on your conversion type, since rooflights are usually exempt from planning permission while hip-to-gable and mansard conversions usually aren’t, but you can override it if your specific property differs. This is a planning tool, not a quote.
For the full picture on what drives these costs, including staircase design, en suite fit-out and roof pitch, see our complete attic conversion cost guide. If you’re still deciding what type of conversion suits your roof, our guide on where to start with an attic conversion is a useful next step, and our attic conversion regulations guide covers the planning and Building Regulations position in detail.
Frequently asked questions
Still have questions about your project? Call 01 270 9764 – we’ll be happy to help!