2026 homeowner cost guide
With house prices high across Ireland, extending can be a practical way to create more space without moving. Start with a realistic budget, then replace online estimates with detailed written quotations based on your own drawings, specification and site.
Whether you are planning a larger kitchen, an open-plan family room or an extra bedroom, understanding the true cost of a house extension in Ireland is essential before work begins.
For early-stage budgeting, Trade Source IRE uses an indicative range of around €2,200–€3,900 per m² for many single-storey extensions, depending on specification, location and complexity. Premium finishes, extensive structural alterations, difficult access and high-cost urban projects can exceed that range.
These are general planning figures, not fixed market rates or quotations. They should not be treated as official SCSI extension prices. Always obtain current written quotations based on your property, drawings, specification and site conditions.
Typical extension costs
Using the €2,200–€3,900 per m² planning range as a simple guide, approximate build costs could look like this:
Indicative build cost before project-specific extras.
Indicative build cost before project-specific extras.
Indicative build cost before project-specific extras.
These figures generally relate to the construction itself and may not include professional fees, kitchens, landscaping, specialist glazing, utility alterations or unforeseen site works.
What increases the cost of an extension?
Every extension is different. A straightforward rear extension with standard finishes can cost considerably less than a kitchen extension with large sliding doors, rooflights, structural steel and bespoke joinery.
Budget drivers
Allow for the whole project
- Ground conditions and foundations
- Structural steel beams
- Roof design and detailing
- Windows, doors and specialist glazing
- Kitchen and utility installations
- Electrical and plumbing work
- Internal finishes and decoration
- Heating and BER upgrades
- Site access and waste removal
- County location and labour availability
Don't forget the hidden costs
Many first-time renovators focus only on the builder's quotation. A complete budget may also need to allow for:
- Architectural or architectural-technologist design
- Structural engineering
- Planning permission where required
- BER assessment and energy advice
- Assigned Certifier and BCAR requirements where applicable
- Building Control fees and compliance documentation where applicable
- Utility connections or service alterations
- Landscaping and external works
- Flooring, decorating, kitchens and other finishes not included in the build price
- A contingency fund - often around 10–15% for early budgeting, adjusted to suit the project
Planning permission in Ireland
Planning exemptions changed in 2026. From 27 July 2026, the existing exemption for an extension of the principal dwelling increased from 40m² to 45m². The exemption is not automatic: the development must satisfy the detailed conditions and limitations in the regulations, and previous extensions can affect the total area available.
Building Regulations and other legal requirements can still apply even where planning permission is not required. Before starting work, check the current position with your local authority and your architect, engineer or other suitably qualified professional.
Read our Planning Permission in Ireland 2026 guide →
Improve your BER while you're building
An extension can also be an opportunity to improve the energy performance of the wider home. Depending on the property and project, homeowners may consider:
- Attic insulation
- External, cavity or internal wall insulation
- High-performance windows and doors
- Air-to-water heat pumps where suitable
- Solar PV panels
- Underfloor or upgraded heating controls
- Improved airtightness and appropriate ventilation
SEAI provides current guidance and grant schemes for eligible home energy upgrades. Grant approval must be in place before grant-supported works begin.
Learn about BER ratings → See our SEAI Grants Ireland guide →
Find trusted extension builders with Trade Source IRE
Choosing the right contractor is just as important as setting the right budget. Trade Source IRE helps homeowners across Ireland submit enquiries for suitable professionals for house extensions, kitchen extensions, renovations, BER upgrades and related work.
Depending on the project, you may need builders, electricians, plumbers, roofers, carpenters, architects or engineers. Whether you are extending a bungalow in Galway, renovating a period home in Cork or creating a modern rear extension in Dublin, start with a clear scope and compare detailed written quotations.
Start your project
Plan the scope before comparing prices
Send your location, project description, approximate size, timeframe and any drawings or photographs you already have. Trade Source IRE can help route your enquiry to potentially suitable professionals where available.
Final thoughts
A house extension is one of the biggest investments you can make in your home. Careful planning, realistic budgeting and experienced professionals can help reduce expensive surprises and improve the quality of the finished project.
Before accepting the lowest quote, compare what is actually included, check references, verify appropriate insurance and qualifications, and agree how variations and staged payments will be handled. A well-planned extension can create valuable living space while supporting comfort, energy efficiency and long-term property value.
Frequently asked questions
How much does a house extension cost in Ireland in 2026?
Trade Source IRE uses an indicative early-planning range of about €2,200–€3,900 per m² for many single-storey extensions. The final cost depends on location, specification, structure, access, finishes and the contractor's current quotation.
How much could a 30m² extension cost?
At an indicative €2,200–€3,900 per m², a 30m² extension gives an early build-only planning range of roughly €66,000–€117,000. Professional fees, kitchens, landscaping, specialist glazing and unforeseen work may be additional.
Can I build a 45m² rear extension without planning permission?
From 27 July 2026, the house-extension exemption increased from 40m² to 45m², but only where all relevant conditions and limitations are met. Previous extensions can count towards the total, so check the specific property with the local authority or a qualified professional.
Should I improve my BER during an extension?
It can be a good time to assess insulation, heating, glazing, ventilation and renewable-energy options because parts of the home are already being altered. A BER assessor or energy professional can help identify suitable measures.
Trusted Irish sources
This guide combines publicly available Irish planning and energy guidance with Trade Source IRE's own indicative budgeting ranges. Construction prices vary, so always obtain project-specific quotations.