House Extension Dublin | Rear, Side & Double Storey Extensions | Dublin Builders

Dublin Builders — Extension Specialists

House Extension Dublin

Transform your home with a professionally designed and built extension. Rear extensions, side returns, double storey and wrap-around extensions across Dublin City and County.

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House Extension Dublin Specialists With 30+ Years Experience

House Extension Dublin projects are among the most popular and cost-effective home improvements available to Dublin homeowners. Rather than face the upheaval and expense of moving, extending gives you the space you need while staying in the home and community you love. At Dublin Builders, we have been delivering house extensions across Dublin for over 30 years, and we understand both the technical requirements and the practical realities of building in an occupied home.

From a single-storey rear extension to open up your kitchen and dining area, to a double storey extension adding bedrooms and bathrooms above, our team manages every element of the project from initial design and planning through to final fit-out. We work across all Dublin housing types — Victorian and Edwardian terraces, semi-detached 1940s and 1950s properties, bungalows, and modern estates — adapting our approach to suit the character of your home and the constraints of your site.

Every project comes with a dedicated project manager, a fixed-price contract, and a commitment to keeping disruption to your household to a minimum throughout the build.

Modern open plan kitchen and dining area created by a Dublin house extension

30+

Years Experience

100%

Project Management

Dublin

Wide Service

Quality

Guaranteed

Types of Extension

House Extension Dublin — All Types Covered

Rear Extensions

The most popular extension type across Dublin, typically used to create a larger open-plan kitchen, dining, and living area flowing out to the garden.

Single and double storey options
Bi-fold or sliding garden doors
Roof lights and glazed roofs
Up to 45m² potentially exempt

Side Return Extensions

Ideal for Victorian and Edwardian terraces across Dublin 6, 8, and the Northside, utilising the narrow side passage to significantly widen the ground floor.

Transforms narrow kitchen layouts
Often exempt from planning
Glazed roof options available
Works well with rear extension

Double Storey Extensions

Maximise the value of your extension project by building on two levels, adding living space downstairs and bedrooms or bathrooms above.

Master bedroom suites
Additional bathrooms
Planning permission required
Significant value uplift

Wrap-Around Extensions

Combining a rear and side return extension into one cohesive space, creating a dramatic transformation of the ground floor layout.

Maximum space gain
Open-plan kitchen-diner-living
Seamless indoor-outdoor flow
Planning permission typically required

Kitchen Extensions

The most common motivation for extending in Dublin. We deliver bright, functional kitchen extensions designed around how your family actually lives.

Open plan kitchen-diner
Island units and breakfast bars
Utility room integration
Full kitchen supply option

Home Office Extensions

A dedicated, insulated, and properly wired home office extension adds real value to your home while solving the challenges of working from home long term.

Separate entrance options
Acoustic insulation available
Cat6 and electrical specification
Garden studio style available

Planning & Regulations

The 45m² Planning Exemption & What It Means for Your Extension

Under Ireland's current exempted development rules, you can extend to the rear of your home by up to 40m² without requiring planning permission, provided your extension meets specific conditions around height, boundaries, and remaining garden space. This covers the majority of single-storey rear extensions built across Dublin and has allowed thousands of homeowners to extend without the delay and cost of a planning application.

What's changing: The Irish Government has proposed increasing the rear extension exemption from 40m² to 45m². Draft regulations were discussed in the Dáil in early 2026 and are at an advanced stage, though the updated rules are not yet signed into law as of July 2026. The existing 40m² threshold currently applies.

When the new 45m² threshold comes into effect, it will give Dublin homeowners meaningfully more flexibility, particularly for those looking to include a utility room or home office alongside a kitchen-diner extension without pushing into planning permission territory. The additional 5m² represents a full utility room or a generous home office alcove in practical terms.

It is important to note that exemption rules come with conditions beyond simply the floor area. The total extension across the house including any previous extensions must not exceed the exempt threshold. Single-storey extensions to the rear must not exceed 4 metres in height, must retain 25m² of private open space to the rear, and must not extend beyond the building line at the side. Our team carries out a full site assessment before any project begins to confirm your exemption status and advise on the best approach for your specific property.

For extensions that do require planning permission — including all double storey extensions, wrap-around extensions, and side extensions on certain property types — we manage the full application process in conjunction with your architect, liaising directly with Dublin City Council, Fingal County Council, South Dublin County Council, or Dún Laoghaire-Rathdown County Council as appropriate.

House Extension Dublin Costs

A single-storey rear extension in Dublin typically costs between €2,200 and €3,000 per square metre, depending on specification, finish level, and site conditions. A 25m² kitchen-diner extension will generally come in at €55,000 to €75,000 fully fitted, while a larger 40m² extension can range from €90,000 to €120,000, again depending on finish. Double storey extensions are priced from approximately €120,000 upwards. All of our projects are tendered on a fixed-price basis, giving you full cost certainty before a single block is laid.

How Long Does a House Extension Take in Dublin?

A single-storey rear extension in Dublin typically takes 10 to 14 weeks from breaking ground to handover, depending on size and specification. Double storey extensions and larger wrap-around projects usually run to 16-20 weeks. If planning permission is required, add 8-12 weeks for the application process before construction can begin. We provide a detailed programme at the outset of every project so you know exactly what to expect and when.

House Extension Dublin — Frequently Asked Questions

Many rear extensions in Dublin fall under exempted development rules, meaning no planning permission is required, provided the extension does not exceed 40m² (or 45m² once new regulations come into effect), remains within set height limits, retains sufficient rear garden space, and meets other conditions. Double storey extensions, wrap-around extensions, and most side extensions require a formal planning application. We carry out a full planning assessment before quoting so you have clarity from the outset.

A typical single-storey rear extension in Dublin costs between €2,200 and €3,000 per square metre depending on specification. A 25m² extension generally ranges from €55,000 to €75,000 fully fitted. Double storey extensions start from approximately €120,000. All of our projects are carried out on a fixed-price contract so there are no unexpected costs mid-build.

A single-storey rear extension typically takes 10 to 14 weeks on site from groundworks to handover. Double storey and wrap-around extensions usually take 16 to 20 weeks. If planning permission is required, allow an additional 8 to 12 weeks for the planning process before construction begins.

Yes, consistently. A well-designed and properly finished house extension in Dublin typically adds between 10% and 20% to the market value of your home, with returns often exceeding the build cost in higher-value areas. Open-plan kitchen-diner extensions are particularly sought after by buyers and tend to deliver strong value uplift. The quality of finish is a significant factor, which is why we do not compromise on materials or workmanship.

In most cases, yes. We plan the build sequence specifically to minimise disruption to your household. The most disruptive phase is when we break through the existing rear wall to connect the extension to the house, which we schedule and complete as quickly as possible. We keep the site clean and secure at all times and communicate the programme clearly so you know what to expect each week.

For exempt single-storey extensions, a full architectural service is not always required, though we recommend involving a designer to ensure the layout works well and the extension integrates properly with the existing house. For planning applications, structural engineering sign-off, or BCAR compliance (required for all extensions), a registered professional must be appointed. We work with a trusted network of architects and engineers and can make introductions if needed.

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Over 30 years building extensions across Dublin
Fixed-price contracts with no hidden costs
Dedicated project manager for every build
Full planning and exemption assessment included
BCAR compliant, fully insured

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