Introduction

Every Irish home has an attic. Most of them are doing nothing.

Some hold a fake Christmas tree and a box of things nobody can throw away. Others have been loosely boarded out as storage. A growing number are being turned into bedrooms, home offices and en-suite master suites that add real space and real value without the cost or disruption of moving house.

Attic conversion cost Ireland is one of the most searched home improvement questions right now — and the answers online are all over the place. You will find everything from €10,000 to €70,000 cited as a "typical" cost.

The truth is that both ends of that range are real. The cost depends on your house type, your roof structure, what you want to do with the space and where in Ireland you live. This guide breaks all of that down clearly, with 2026 prices, honest data and the things most guides leave out entirely.

If you already know your house type and county, our free attic conversion cost calculator returns an indicative range in under a minute — useful before you ring contractors.

Attic Conversion Cost Ireland — Quick Answer

Most Irish homeowners pay between €18,000 and €55,000 for an attic conversion in 2026.

A basic Velux conversion — adding roof windows, strengthening the floor and fitting stairs — starts around €18,000–€28,000 on a standard semi-D. A full rear dormer with en-suite runs €35,000–€55,000. A hip-to-gable conversion with a dormer on a larger detached home can reach €60,000–€70,000+.

Here is where those numbers come from. According to a Tradesmen.ie survey of Irish contractors, prices start from €1,000 per square metre for a basic conversion. They rise to €1,600 per square metre or more for higher finishes or complex structural work. A Chartered Building Surveyor from the Society of Chartered Surveyors Ireland (SCSI) puts a standard 25–30 m² bedroom and en-suite at around €25,000–€26,000 before decoration costs.

Real-world quotes from Irish homeowners on Boards.ie in 2024 and 2026 show:

  • Semi-D, no en-suite, basic Velux: €24,000–€30,000
  • Semi-D, rear dormer, no en-suite: €30,000–€38,000
  • Semi-D, rear dormer, with en-suite: €38,000–€50,000

These are not estimates. These are actual quotes from actual jobs.

Use our free attic conversion cost calculator to get a figure based on your house type and county in under 60 seconds.

What Type of Attic Conversion Do You Need?

There are four main types of attic conversion in Ireland. Each one is a different project with a different price tag. For dormer-heavy scenarios and pricing bands, see Cost by conversion type below — useful once you know you need headroom from a dormer rather than rooflights alone.

Velux (rooflight) conversion

This is the simplest and cheapest option. No changes are made to the roof structure. Velux or rooflight windows are added at the rear. The attic floor is strengthened, insulation is added, a staircase goes in and the room is plastered and finished.

A Velux conversion only works if your attic already has enough head height — at least 2.4 metres at the centre point over half the floor area. If it does not, you need a dormer. Narrow footprints and tighter spans are covered under Cost by house type below.

Rear dormer conversion

A dormer extends the back of the roof outward and upward. This creates a box-shaped room with a flat or slightly sloped roof. It adds significant headroom and usable floor space.

Most rear dormers on standard Irish semi-Ds and terraced houses do not need planning permission. They are exempt under Class 14 of the Planning and Development Regulations, provided the dormer area does not exceed 40 m² and is not visible from the front.

Side dormer conversion

A side dormer extends the roof sideways. This is more common on semi-detached or end-of-terrace houses where the side elevation has room. It works well when the rear of the house faces a garden wall or has limited structural options.

Hip-to-gable conversion

On a detached home or semi-D where the side of the roof slopes down (a hip), this conversion replaces the sloped side with a vertical gable wall. It gains a lot of internal floor space. Planning permission is usually needed.

Cost by Conversion Type

Conversion type Typical cost range (2026) Planning needed? Best for
Velux (rooflight only) €18,000–€28,000 Usually no Good head height already
Rear dormer €28,000–€45,000 Usually no (rear) Most semi-Ds and terraces
Side dormer €30,000–€48,000 Check local rules End-of-terrace, semi-D
Hip-to-gable €35,000–€55,000 Usually yes Detached homes
Hip-to-gable + dormer €45,000–€70,000+ Yes Max space, detached

These figures are for a basic room without an en-suite. Add €8,000–€15,000 for a bathroom depending on plumbing access and spec.

Cost by House Type

Your house type matters almost as much as your conversion type. It determines the attic size, the roof structure and the access options.

Terraced house

Most terraced houses in Ireland — especially those built before 1980 — have cut roofs with good head height. A Velux conversion on a narrow terrace typically runs €18,000–€28,000. A rear dormer adds a further €8,000–€15,000 on top of that. Space is the main limit. Terraced attics are often narrower, which limits what you can do with the room.

Semi-detached house

The semi-D is the most common house type in Ireland and the most common attic conversion project. Roof areas average 55–75 m² and most semi-Ds built after 1980 have truss roofs, which need structural work before conversion (see below). Total cost for a Velux conversion: €20,000–€30,000. Rear dormer with no en-suite: €30,000–€42,000. Rear dormer with en-suite: €40,000–€55,000.

Detached house

Detached homes have bigger attic footprints — often 100 m² or more — and more options for dormers or hip-to-gable work. The structural work is more extensive. Expect €30,000–€45,000 for a Velux conversion on a large detached home and €45,000–€70,000+ for a full hip-to-gable with dormer and en-suite.

Bungalow

Bungalows are a special case. The attic can be very large — sometimes 130 m² or more — but head height is often lower than in two-storey homes. Many bungalow attics need a rear dormer to gain enough height for a habitable room. Costs range from €30,000–€55,000 depending on the type and size.

Full Cost Breakdown — What Are You Actually Paying For?

Here is where the money goes on a standard rear dormer conversion for a 3-bed semi-D:

Item Typical cost
Structural survey and engineer cert €600–€1,200
Truss removal and steel beams (if needed) €5,000–€12,000
Floor strengthening and boarding €2,000–€4,000
Dormer structure (walls, roof, waterproofing) €8,000–€16,000
Velux or dormer window (2 units, fitted) €2,000–€4,500
Rafter and floor insulation €2,000–€4,500
Staircase (code-compliant, new) €3,500–€7,500
Plasterboard and plastering €2,500–€4,500
Electrics (lighting, sockets, smoke alarm) €1,000–€2,000
Fire door to landing €350–€650
Basic decoration (paint, floor finish) €1,000–€2,500
Total without en-suite €28,000–€60,000
En-suite bathroom (add-on) €8,000–€15,000
Total with en-suite €36,000–€75,000

The biggest variables are the truss removal and the dormer structure. Get these two items quoted separately so you can see what drives the price.

If you are also pricing roof coverings or a full strip-and-recover on the main roof, cross-check against our new roof cost Ireland framework so scopes do not overlap twice.

The Cut Roof vs Truss Roof Problem

This is the single most important cost factor that most guides skip over. It can add €5,000–€15,000 to your total.

Cut roof — found in most Irish homes built before about 1980. The roof timbers were cut and fitted on site by a carpenter. There is usable open space in the attic. These roofs are relatively straightforward to convert.

Truss roof — found in almost all Irish semi-Ds and terraced houses built after 1980. The roof frames were made in a factory. They are light and fast to install on a building site. But they fill the attic with a web of diagonal timbers called webbing. There is very little usable space.

To convert a truss roof, the webbing must be removed and replaced with steel RSJ beams. These beams carry the load the webbing was handling. Steel materials cost €1,000–€3,000. Labour, engineering sign-off and temporary propping add another €3,000–€10,000.

As SCSI chartered surveyor Val O'Brien notes, truss roofs "do not lend themselves to easy conversion" and the work adds considerable cost compared to traditional cut roofs.

How to tell which you have: open your attic hatch and look up. If you see a web of diagonal wooden braces going up to the ridge, you have a truss roof. If you see open space with a ridge beam and rafters, you have a cut roof.

Always ask your contractor to confirm this in writing before signing any quote.

Does Your County Affect the Price?

Yes. Labour rates vary across Ireland and they affect the final cost of a conversion significantly.

Region Typical price vs national average
Dublin city and inner suburbs +15–20%
Cork city +7–10%
Galway and Limerick At national average
Rural Leinster At national average
Rural Munster and Connacht -5–8%

A rear dormer conversion that costs €35,000 in Galway will likely cost €40,000–€42,000 in Dublin. That is the same job, the same spec, the same materials — just a higher labour rate.

For Dublin-specific uplifts, budget roughly 15–20% above national averages on labour — the regional comparison in this section is what most contractors reflect in quotes.

What Hidden Costs Catch People Out?

Structural surprises

Many attic conversion quotes look reasonable until the contractor opens up the roof. Old homes can have rotten ridge boards, weakened rafters or water damage that was not visible from below. These add cost once work has started. Budget 10–15% extra on any home over 25 years old.

Staircase space

A code-compliant staircase needs a run of about 3–4 metres on the floor below. If your landing is tight, the staircase may eat into a bedroom below. Some homeowners have to reconfigure the bedroom below to fit the staircase — and that is a second job that was not in the original quote.

Plumbing for the en-suite

If you want an en-suite, the cost depends heavily on how far the attic is from your main plumbing stack. If the stack runs through the house and the attic is directly above it, plumbing is straightforward. If it is on the other side of the house, you are looking at a much longer pipe run and higher cost.

Planning fees if required

A hip-to-gable conversion or any dormer facing the front of the house needs planning permission. Architect drawings cost €1,500–€3,000. Planning application fees are €65. If permission is refused and an appeal is needed, add more time and money.

Irish home with roof and materials — use the calculator for a tailored estimate

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Commencement notice and engineer cert

These are legal requirements for any attic conversion. Your engineer or architect submits the commencement notice before work starts and certifies the work at the end. Expect €500–€1,500 for this. It is not optional. Without it, the conversion has no legal status and will cause problems when you sell.

Insulation-only grants are a separate conversation from a full conversion — if you are stacking insulation work with roof upgrades, read SEAI roof insulation grant 2026 for eligibility and amounts before you fix specifications.

The Spray Foam Warning

This is something almost no Irish attic conversion guide mentions. It matters a great deal.

If your attic already has spray foam insulation applied to the rafters, this can cause problems.

Spray foam is applied as a liquid and expands to fill every gap. It bonds to the timber. When it is applied badly or where ventilation is poor, it can trap moisture and cause timber to rot underneath. The issue is that because the foam bonds to the rafters, structural assessors cannot inspect the timber underneath without removing the foam.

In the UK, this has caused some mortgage lenders and surveyors to raise concerns about properties with spray foam. The UK's Property Care Association found in 2025 that 35% of properties it inspected had defects linked to spray foam.

In Ireland, the issue is less well documented, but Irish homeowners on Askaboutmoney.ie have reported surveyors advising against buying homes with spray foam in the attic.

The practical advice:

  • If you are buying a home and the attic has spray foam, get a specialist roof inspection before you proceed
  • If you are having an attic conversion done, insist on mineral wool or rigid board insulation — not spray foam
  • If your attic already has spray foam, tell your surveyor before the conversion begins

A good attic conversion contractor will use mineral wool or rigid board insulation as standard. O'Meara Attic Solutions, one of Ireland's most established conversion companies, use Volcalis mineral wool as their standard specification for exactly this reason.

Habitable vs Non-Habitable — Why It Matters for Cost and Resale

This is the distinction that most Irish attic conversion guides explain badly, if at all. It changes both the cost and the legal status of the room.

Non-habitable conversion

Most Irish attic conversions — according to SCSI chartered surveyor Val O'Brien — are technically non-habitable. They do not meet the full building regulations for a room that can be marketed as a bedroom. The main reason is usually head height: the 2.4m ceiling height rule over 50% of the floor area is not met.

A non-habitable conversion is cheaper. It can be used as a study, a playroom, occasional storage or a hobby room. But you cannot legally call it a bedroom in a property listing. Buyers' solicitors ask for building certificates. If the conversion was done without proper sign-off and is being listed as a bedroom, this will cause problems at sale.

Habitable conversion

To have a properly habitable room, you need:

  • 2.4m ceiling height over at least 50% of the floor area
  • A code-compliant fixed staircase (not a pull-down ladder)
  • A window large enough to escape from in a fire
  • A fire-rated door on the landing
  • Proper insulation to Part L standards
  • Electrical installation with smoke alarm
  • A commencement notice filed before work started
  • A certificate of compliance issued at the end

This costs more to do correctly. But it is the version that adds the most value to your property and that survives scrutiny during a sale.

Does an Attic Conversion Add Value in Ireland?

Yes — consistently and significantly.

According to SCSI Chartered Building Surveyor Val O'Brien, a properly certified attic conversion can add approximately €25,000 to the value of an Irish home compared to a similar house without one. This is a specific, verifiable figure from a professional body — not a marketing claim.

The SCSI House Extension and Conversion data cited in multiple Irish property guides suggests attic conversions deliver a return of 12–15% on property value in Dublin.

On a home worth €400,000, a 12% uplift is €48,000. A conversion costing €35,000 would represent a net gain in equity of €13,000 — before factoring in years of use of the extra room.

The key condition for value is certification. An attic converted without a commencement notice and certificate of compliance does not add value in the same way. It can actually reduce value because the paperwork problem must be resolved before the sale can proceed.

Attic Conversion vs Home Extension — Which Is Better Value?

Most Irish homeowners who need more space ask this question eventually.

Factor Attic conversion Ground-floor extension
Cost per m² of new space €1,000–€1,600 €2,000–€3,500
Disruption during build Low High
Planning permission Usually no Usually yes
Build time 6–10 weeks 12–24 weeks
Best for Extra bedroom, office Bigger kitchen, living room
Property value uplift €25,000+ (SCSI) Variable

An attic conversion costs roughly half as much per square metre as a ground-floor extension. It takes less time. It causes less disruption. It usually does not need planning permission.

The reason to choose a ground-floor extension instead is use. If you need a bigger kitchen, a larger living room or a playroom that opens onto the garden, you need to extend downward. An attic gives you overhead space. It is ideal for a bedroom, a home office or a guest room. It does not work well as a living space for young children who need garden access.

If you are pricing roof work on the main house at the same time, keep attic scope separate from new roof cost Ireland quotes so you compare like with like.

If space is the goal and a bedroom or office meets that need, the attic conversion wins on value almost every time.

How Long Does an Attic Conversion Take?

Conversion type Typical build time From first call to done
Velux conversion 4–6 weeks 8–12 weeks
Rear dormer 6–10 weeks 10–16 weeks
Hip-to-gable 8–12 weeks 12–18 weeks
Hip-to-gable + dormer 10–14 weeks 14–20 weeks

The "from first call to done" timeline includes getting quotes, waiting for a contractor slot and any planning or commencement notice lead time. Booking in winter (October to February) cuts wait times significantly compared to peak season.

Most of the work happens above your existing ceiling. You can live normally in the house throughout. The main disruption is the staircase day — when the landing ceiling is opened up to fit the new stairs.

What Should a Good Attic Conversion Quote Include?

A proper quote for an attic conversion in Ireland should confirm all of these in writing:

  • Type of conversion (Velux, dormer, hip-to-gable)
  • Whether the roof is cut or truss and how the structural work will be handled
  • Steel beam specification if needed
  • Flooring spec (OSB decking, or upgrade material)
  • Window brand and specification (Velux model number)
  • Insulation type and depth (mineral wool, rigid board — not spray foam)
  • Staircase type and specification
  • Electrics included (lighting, sockets, smoke alarm)
  • Fire door included
  • Plastering included or separate
  • En-suite plumbing included or separate
  • Commencement notice — who handles it
  • Engineer cert — included or separate
  • VAT at 13.5%
  • Payment schedule (typically three stages: start, midpoint, completion)
  • Workmanship warranty (minimum 10 years)
  • Start and finish dates

If any of these are missing, ask before you sign anything.

How to Get a Fair Quote

Before calling anyone:

  • Measure your attic head height at the centre point
  • Look inside the attic hatch — identify whether you have a cut or truss roof
  • Decide on the use (bedroom, office, storage)
  • Decide on extras (en-suite, dormer, staircase type)

Getting quotes:

  • Get three written quotes
  • Ask each contractor to quote the same spec so you can compare like for like
  • Ask about the commencement notice and engineer cert — who handles it and is it included?

The payment structure

The standard payment schedule for attic conversions in Ireland is three stages. This matches what tradesmen report on Tradesmen.ie: a deposit at the start, a payment at the midpoint and the balance on completion. Never pay more than 30% upfront. Never pay 100% before the job is finished and certified.

Red Flags in Attic Conversion Quotes

Quote with no mention of structural engineering or certifier. Every attic conversion needs a commencement notice and engineer sign-off. If a contractor does not mention this, they may not be planning to do it properly.

Spray foam recommended as insulation. Standard practice is mineral wool or rigid board. Spray foam is harder to inspect, can cause moisture problems and has raised concerns in the resale market. Ask for a different spec.

Full payment upfront. A legitimate contractor takes a deposit and stages payments through the job. Paying everything before work starts leaves you with no protection.

Quote is 30% below the others. On a complex job like an attic conversion, a very low quote almost always means something is not included. Check for the steel beams, the staircase, the engineer cert and the VAT.

Verbal quote only. Every attic conversion needs a written contract. Without one, you have no protection if disputes arise.

Frequently Asked Questions

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

Most homeowners pay €18,000–€55,000. A basic Velux conversion on a semi-D starts around €18,000–€28,000. A full rear dormer with en-suite runs €38,000–€55,000. Dublin prices are 15–20% above these figures.

Does an attic conversion add value to an Irish home?

Yes. SCSI Chartered Building Surveyor Val O'Brien estimates a properly certified conversion adds about €25,000 to property value. The key condition is certification — a commencement notice and certificate of compliance must be in place.

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

Not for a Velux conversion or standard rear dormer on most houses. Planning is required for front dormers, hip-to-gable work and alterations on protected structures. A commencement notice is always required, regardless of planning status.

How long does an attic conversion take?

A Velux conversion takes 4–6 weeks on site. A rear dormer takes 6–10 weeks. From first call to completion, allow 10–16 weeks including getting quotes and booking a slot.

What is the difference between a cut roof and a truss roof?

A cut roof has open timber rafters — common in homes built before 1980. A truss roof has factory-built triangular frames — common after 1980. Truss roofs need the webbing removed and steel beams fitted, which adds €5,000–€15,000 to the job.

Is spray foam insulation okay for an attic conversion?

We recommend against it. Spray foam bonds to the timber and cannot be removed without significant work. It can trap moisture, it makes structural inspection difficult and it has raised concerns with surveyors in the Irish resale market. Use mineral wool or rigid board insulation instead.

What payment schedule should I expect?

Three stages is standard: a deposit at the start, a payment at the midpoint and the balance on completion. Never pay 100% upfront.

Conclusion

An attic conversion is one of the best value home improvements available to Irish homeowners in 2026. It costs roughly half as much as a ground-floor extension per square metre. It takes less time to build. It causes less disruption. And when it is done properly and certified, it adds real value to your property.

The most important things to get right are:

  • Know your roof type before you get a quote — cut or truss makes a big difference to cost
  • Insist on mineral wool or rigid board insulation, not spray foam
  • Make sure the quote includes the commencement notice and engineer cert
  • Pay in three stages, never upfront
  • Get three written quotes and compare them on the same spec

The most common mistakes are accepting a quote with no mention of certification, paying too much upfront and using spray foam insulation that causes problems years later.

Get the spec right, get the paperwork done and you will have a room that adds value and serves your family for decades.

Use the free attic conversion cost calculator to get a price estimate for your house type and county before you start calling contractors.

Sources

All prices are planning estimates based on April 2026 contractor rates. Always get three written quotes from a CIF or CIRI registered contractor before committing to any attic conversion work.