A dormer attic conversion is the most popular way to add a full bedroom — or bedroom with en-suite — to a Dublin home. It's affordable, practical and works on the vast majority of semi-detached and terraced houses across the city.
Here's everything you need to know before you start.
What is a Dormer Conversion?
A dormer is a structural extension that projects vertically from the existing roof slope. It creates a box-shaped structure with a flat or pitched roof, dramatically increasing both headroom and floor space compared to a basic Velux conversion.
Most Dublin dormer conversions are built to the rear of the property, keeping the front roofline unchanged and avoiding the need for planning permission in most cases.
Dormer Conversion Costs in Dublin 2026
| Specification | Typical Cost |
|---|---|
| Standard rear dormer (1 room) | €25,000 – €32,000 |
| Dormer with en-suite bathroom | €30,000 – €40,000 |
| Full-width rear dormer | €35,000 – €45,000 |
| Dormer + Velux to front | €30,000 – €42,000 |
💡 The average Dublin dormer conversion adds a full double bedroom and en-suite for around €35,000 — and typically adds €50,000–€70,000 to the property value.
What's Included in a Full Dormer Build?
- Structural engineer drawings and calculations
- All steelwork and structural carpentry
- Dormer roof construction (flat or pitched)
- Full insulation — walls, ceiling and floor
- Plastering and dry-lining throughout
- Electrical first and second fix
- New attic staircase
- Windows and roof lights
- En-suite plumbing if required
- Fire door installation
Do I Need Planning Permission for a Dormer in Dublin?
In most cases, a rear dormer in Dublin is exempt from planning permission under the Planning and Development Regulations — provided the following conditions are met:
- The dormer is to the rear of the property only
- The floor area created is under 40 sq metres
- The ridge height of the roof is not increased
- The property is not in a protected structure or an Architectural Conservation Area
⚠️ If you live in certain Dublin areas — particularly older city centre properties or protected structures — you may need planning permission. Your contractor will confirm this during the initial survey.
How Long Does a Dormer Conversion Take?
A standard rear dormer in Dublin typically takes 6 to 10 weeks from start to finish. The timeline breaks down roughly as follows:
- Week 1–2: Structural steel installation and roof opening
- Week 2–4: Dormer frame, roof covering and weatherproofing
- Week 4–6: Internal fit-out — insulation, dry-lining, electrics
- Week 6–8: Plastering, staircase, windows and finishing
Is My Home Suitable for a Dormer?
The majority of Dublin homes are suitable for a rear dormer conversion. Key factors include:
- Roof pitch — steeper roofs give more internal space
- Ridge height — ideally 2.2m+ at the apex
- Structural condition of existing roof timbers
- Party wall considerations for semi-detached or terraced properties
The easiest way to find out is a free survey — takes about 30 minutes and will tell you exactly what's possible.
Get a Free Dormer Quote
We survey Dublin, Wicklow and Kildare properties. Free no-obligation survey and quote within 48 hours.
Book Free Survey