How much does a house extension cost in Ireland?

In 2026, a house extension in Ireland costs between €2,000 and €3,500 per square metre. A standard 30 m² rear kitchen extension typically costs between €60,000 and €90,000, depending on structural steel, glazing specifications, and finishes.

Do I need planning permission for a house extension in Ireland?

In Ireland, you do not need planning permission for a ground-floor extension to the rear of your house if the total floor area does not exceed 40 square metres, and you still leave at least 25 square metres of private garden. All other types, including front or side extensions and multi-storey builds, generally require planning permission.

How long does a house extension take to build?

A standard single-storey ground-floor extension (30 m²) typically takes 10 to 16 weeks to construct. A larger double-storey extension can take 16 to 24 weeks. The timeline includes groundwork, masonry/timber framing, structural steels, roofing, glazing, plumbing/electrical first-fixes, plastering, and final finishes.

What is the maximum size of extension I can build without planning permission?

The maximum size of a domestic extension you can build under exempted development rules in Ireland is 40 square metres. If your house has been extended previously, the combined floor area of all extensions (both past and new) must not exceed 40 square metres.

What should I check before hiring a house extension builder?

Before hiring an extension builder in Ireland, verify they have active public liability and employer's liability insurance, request references from previous local clients, confirm their CRO company registration, and check if they use standard RIAI contracts. You can find fully verified house extension builders on BuildTrade.ie.

Is a house extension cheaper than buying a new home in Ireland?

In most cases, building an extension is more cost-effective than buying a new house when you factor in property search, estate agent fees, stamp duty (1% to 2%), legal fees, and moving costs. Extending allows you to customize your current home without leaving your community.

Do I need an architect for a house extension in Ireland?

While not legally mandatory for small extensions under 40 m², hiring an architect or architectural technologist is highly recommended. They ensure structural safety, maximize natural light, manage building regulations compliance (Part A, Part L), and provide detailed construction drawings for builders to quote on.

How do I finance a house extension in Ireland?

Homeowners in Ireland typically finance extensions through personal savings, credit union home improvement loans, or by topping up their existing mortgage. Some energy-efficiency upgrades performed during the extension (like wall or floor insulation) may also qualify for individual SEAI grants.

House Extension Builders in Ireland

Are you looking for verified house extension builders in Ireland to expand your living space? Adding a home extension is a fantastic way to gain extra square footage, add value to your property, and tailor your home to your family's needs. At BuildTrade.ie, we connect you with vetted, fully insured, and highly experienced builders in Ireland who specialize in single-storey, double-storey, and wrap-around home extensions. All our listed contractors are checked against CRO records and public liability insurance registers to guarantee master standards. Whether you want to add a modern open-plan kitchen extension, an extra bedroom, or a home office, our local professionals ensure compliance with Irish Building Regulations and RIAI standard contracts. Compare free quotes from trusted local builders near you today and start planning your perfect house extension in Ireland.

CIRI Registered

Qualified Builders

€2,000 - €3,500

Average Cost per m²

40 m²

Planning Exemption Limit

100% Insured

Public & Employer Liability

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What is House Extensions?

A house extension is the process of adding extra living space onto an existing residential building, requiring architectural design, structural engineering, and professional construction that conforms to Irish Building Regulations.

How Much Does House Extensions Cost in Ireland?

Here are typical price ranges and baseline estimates for house extensions in Ireland.

Extension Type	Size (m²)	Est. Gross Cost	Average Duration	Planning Required
Standard Single-Storey Rear	20 - 30 m²	€45,000 - €75,000	8 - 12 Weeks	No (if <40m² total)
Large Single-Storey (Open-Plan)	30 - 45 m²	€70,000 - €120,000	12 - 16 Weeks	Depends on total size
Two-Storey Extension	40 - 65 m²	€100,000 - €180,000	16 - 24 Weeks	Usually Yes
Bespoke Glazed Wrap-Around	30 - 50 m²	€85,000 - €150,000	14 - 18 Weeks	Usually Yes

* Costs are baseline estimates for 2026. Actual quotes depend on structural steel requirements, glazing systems, and location.

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External Wall Insulation Ireland Home Retrofit Ireland General Builders Ireland ICF Construction Ireland

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