The average attic conversion cost in Ireland ranges from €18,000 to €60,000 for a rooflight or dormer conversion, depending on the size of the attic, the type of conversion, and the finish. Hip-to-gable and mansard conversions cost more, from €40,000 to €110,000+. In Dublin, a rooflight conversion starts from €22,000, and most homeowners adding a dormer to a standard semi-detached attic for a bedroom or home office spend between €35,000 and €60,000 for a fully finished space. This guide breaks down every cost factor so you can budget accurately before you get a single quote.
Attic Conversion Cost Calculator
Pick your conversion type, location and floor area for a quick total budget, including VAT at 13.5% and a 10 to 15% contingency. For property age, an en suite, a bespoke staircase, extra structural work and planning, open the full attic conversion calculator for the full breakdown.
Quick estimate
€39,000 to €69,000
Total budget to plan for, including VAT at 13.5% and a 10 to 20% contingency.
What Does an Attic Conversion Cost Include?
A properly priced attic conversion quote from a reputable contractor should include structural work, insulation, electrics, and finishing as standard. If a quote looks unusually low, it is worth checking what is and what is not included.
Structural and Building Work
- Steel beam installation or structural reinforcement of the floor
- Staircase design and installation (a significant portion of the overall cost)
- Dormer structure or gable extension if applicable
- Roof alterations and weatherproofing
- Compliance with the Building Regulations, including Part A (structure), Part B (fire), Part K (stairs) and Part L (energy), with an engineer’s sign-off
Insulation and Airtightness
- Roof insulation to current Building Regulations standards (minimum U-value 0.16 W/m²K)
- Floor insulation between joists
- Airtightness membrane and taping
- Wall insulation to dormer cheeks where applicable
Electrics and Lighting
- Dedicated consumer unit circuit or extension from existing board
- Lighting – recessed, pendant, or feature, depending on specification
- Power sockets (minimum 4–6 for a standard room)
- Smoke detector as required under Building Regulations
- TV/data points if required
Windows and Ventilation
- Velux rooflight windows (standard on most conversions)
- Dormer windows with double-glazed units (dormer conversions)
- Trickle ventilation or mechanical ventilation as required
Finishing
- Plasterboard drylining and skimming
- Floor – typically engineered timber, carpet, or LVT
- Painting and decorating (two coats throughout)
- Skirting boards, architraves, and door installation
- Bathroom or en suite fit-out if included in scope
Attic Conversion Cost Breakdown
Sources: Build Me project data and 2026 Irish market benchmarks. Costs shown are for a standard dormer attic conversion of 20 to 30 m² on a semi-detached house in Dublin and the surrounding area. Structural steel costs vary significantly depending on the existing roof structure. Staircase costs assume a standard design; bespoke or space-saving stairs cost more. Finishing costs include plasterboard, skimming, flooring, painting, and joinery. Add 10–15% contingency to all figures (15–20% for pre-1970 houses). An en suite adds €6,000–€12,000 to the total (€12,000–€20,000 high spec). Outside Dublin, the same dormer typically costs €28,000–€48,000.
Attic Conversion Cost Per Square Metre in Ireland
Attic conversion costs in Ireland work out at roughly €700 to €4,400+ per m² of usable floor area depending on the type of conversion, with Dublin rates running about 15 to 25% above the rest of Ireland. The figures below are based on a typical 25 m² conversion.
| Conversion Type | Cost Per m² (Ireland) | Cost Per m² (Dublin) |
|---|---|---|
| Rooflight conversion | €720 to €1,200 | €880 to €1,400 |
| Dormer conversion | €1,120 to €1,920 | €1,400 to €2,400 |
| Hip-to-gable conversion | €1,600 to €2,600 | €1,920 to €3,000 |
| Mansard conversion | €2,200 to €3,600+ | €2,600 to €4,400+ |
These per m² figures are based on usable floor area after conversion, not the total roof footprint. A standard semi-detached attic in Dublin typically yields 20 to 35m² of usable space depending on the roof pitch and conversion type. Because the structural work, staircase and fire protection are largely fixed costs, the price does not rise in a straight line with size: a smaller attic costs more per m² and a larger one less. A dormer conversion producing 28 m² of usable floor area in Dublin, for example, costs €35,000 to €60,000 (about €1,250 to €2,140 per m²), while a 38 m² dormer conversion costs around 10% more, €38,500 to €66,000. Under 20 m², knock about 5% off; between 41 and 45 m², add about 20%.
What Factors Affect Attic Conversion Costs in Dublin?
No two attic conversions are identical, even in identical houses on the same street. Several variables move the price up or down significantly.
1. The Size and Pitch of Your Roof
Roof pitch is the single biggest determinant of whether an attic conversion is straightforward or complex. A steep-pitch roof, common in Victorian terraces in Rathmines, Ranelagh, and Drumcondra – typically gives you more headroom to work with and can reduce the structural alterations needed. Low-pitch roofs, more common in 1970s and 1980s semi-detached houses in areas like Terenure or Clontarf, often require a dormer or hip-to-gable extension to create adequate standing height. There is no single legal minimum ceiling height, but as a rule of thumb you need about 2.4m between the top of the ceiling joists and the underside of the ridge; under about 2.2m usually means raising the roof or adding a dormer. The stairs need 2.0m headroom (Technical Guidance Document K).
2. The Staircase
This is the cost item that catches most people off guard. A standard attic staircase is part of the base price of every conversion, but where space is tight and a bespoke or space-saving design is required, expect to add €3,000 to €8,000. The staircase must comply with Part K of the Irish Building Regulations, including handrail heights, minimum tread depth, and head clearance. Cutting through a ceiling and configuring the landing often requires structural work to the floor below, which adds to the cost.
3. En Suite or Wet Room
Adding an en suite to an attic conversion is extremely common and adds €6,000 to €12,000 to the overall cost for a standard specification, or €12,000 to €20,000 for a high-spec or complex en suite, plus about two weeks on site. This includes extending the soil stack, running hot and cold water supply, installing a shower enclosure, toilet, basin, tiling, and all associated plumbing and waterproofing. A well-designed en suite significantly increases the value of the conversion from a resale and rental perspective.
4. Insulation Standard
Building Regulations set minimum energy performance standards, but many homeowners, particularly those improving a BER rating ahead of sale or rental, choose to go beyond the minimum. Upgrading to Passivhaus-adjacent insulation levels or installing mechanical heat recovery ventilation (MHRV) will increase costs but deliver better energy performance and comfort year-round.
5. Access and Location Within Dublin
Working in tight urban areas, particularly on Victorian and Edwardian terraces in south Dublin adds cost. Scaffold over a public footpath, skip permits from Dublin City Council, restricted crane access, and parking limitations for contractors all affect the final price. This is rarely factored into ballpark estimates but can add €2,000 to €5,000 on a complex inner-city project.
📊 Data Point: According to the Society of Chartered Surveyors Ireland (SCSI) House Extension and Conversion Report, attic conversions deliver an average return of 12–15% on property value in Dublin, typically one of the highest ROI home improvements available.
We convert attics across Dublin and north Wicklow, from rooflight and dormer conversions to hip-to-gable, with one team from the structure to the finishes. See our attic conversions in Dublin, or try the attic conversion cost calculator for a full breakdown.
How Planning Permission Can Affect Attic Conversion Costs
Planning permission is not always required for an attic conversion, but when it is, it adds both time and cost to the project. Architectural drawings, planning applications, and any revisions typically add €1,500 to €5,000 to the overall budget, and the process typically takes 12 to 16 weeks from preparing drawings to a decision (an 8-week council decision period plus a 4-week appeal window, plus time for drawings and the site notice) before work can begin on site. Once on site, a rooflight conversion typically takes 6 to 8 weeks and a dormer conversion 8 to 10 weeks.
Whether permission is required depends on the type of conversion and what it does to the external appearance of the property. Since 27 July 2026, the 2026 exempted development regulations (S.I. 338 to 344 of 2026) have made dormers and front rooflights easier to build without planning permission.
Rooflight (Velux) conversions
Involve no change to the roof profile. Rooflights on the rear roof that don't materially change the appearance of the house are generally exempt, and under the new Class 1C you can also fit up to two rooflights on the front roof, each no more than 100 cm × 90 cm, without planning permission. No planning cost, no delay.
Dormer conversions
To the side or rear of the property are now exempted development under the new Class 1B, provided the internal volume of all dormers together is no more than 30 m³, they are no higher than the roof ridge and they are set back at least 20 cm from the eaves. A typical rear dormer on a standard Dublin semi-detached can usually proceed without planning. A dormer to the front elevation still requires full planning permission, adding the €1,500 to €5,000 cost above. If you're unsure, a Section 5 declaration from your council (€80, normally decided within 4 weeks) confirms whether your design is exempt. The exemptions don't apply to protected structures or where they would materially affect the character of an Architectural Conservation Area.
Hip-to-gable and mansard conversions
Involve material alterations to the roof structure and require full planning permission from your local authority, whether that is Dublin City Council, South Dublin County Council, Dún Laoghaire-Rathdown, or Fingal. Factor this cost into your budget from the outset.
⚠️ Important: Even where planning permission is not required, the work must meet the Building Regulations (Parts A, B, K and L). Get an engineer’s design and a sign-off or certificate of compliance for your records. Your contractor should arrange this as a matter of course; if they do not, ask why.
Attic Conversion vs Extension Costs in Ireland
An attic conversion is not always the right solution. Here is how it compares to other popular ways to add space in a Dublin home (Dublin prices, standard finish).
| Option | Typical Cost | Space Added | Planning | Disruption |
| Attic Conversion | €22,000–€60,000 | 15–40m² | Often exempt | Low–Medium |
| Single-Storey Rear Extension | €40,000–€138,000 | 15–40m² | Often exempt (up to 45m²) | Medium |
| Two-Storey Rear Extension | €66,000–€186,000 | 30–60m² | Usually required | High |
| Garage Conversion | €18,000–€65,000 | 15–25m² | Usually exempt | Low |
Frequently Asked Questions
How much does an attic conversion cost in Ireland?
An attic conversion in Dublin costs between €22,000 and €60,000 for most residential properties. A standard rooflight conversion in a semi-detached house runs from €22,000 to €35,000 and a dormer conversion from €35,000 to €60,000, with an en suite adding €6,000 to €12,000. Hip-to-gable conversions cost €48,000 to €75,000 and mansards €65,000 to €110,000+. Dublin rates run about 15–25% higher than the rest of Ireland, where a rooflight conversion costs €18,000 to €30,000 and a dormer €28,000 to €48,000.
What is the cheapest type of attic conversion in Ireland?
A rooflight (Velux) attic conversion is usually the most affordable option. Because the existing roof structure remains unchanged, the work mainly involves strengthening the floor, installing stairs, insulation, and roof windows. This type of conversion typically costs between €22,000 and €35,000 in Dublin, or €18,000 to €30,000 in the rest of Ireland.
Why are attic conversions expensive in Ireland?
The main cost drivers are structural steel installation, staircase construction, insulation upgrades, and labour. Irish Building Regulations require reinforced floor joists, fire safety measures, and proper insulation standards, all of which add to the total project cost.
How much value does an attic conversion add to a house in Ireland?
A professionally completed attic conversion can increase a property’s value by approximately 12–15%. In Dublin and other high-demand areas, this can add €40,000 to €80,000 or more to a home’s market value, often exceeding the cost of the conversion itself.
What factors affect the cost of an attic conversion in Ireland?
Several factors influence the final cost, including the size of the attic, roof structure, head height, type of conversion (rooflight or dormer), staircase location, and whether an en suite bathroom is added. Labour costs and access constraints can also increase the overall price.
