HOW TO HIRE · TRADES & CONSTRUCTION · CHECKED OCTOBER 2026
How to hire an extension builder in Ireland
The checks, the questions and the paperwork.
A house extension in Ireland costs €2,500–€4,500 per m², typically around €3,200. Here is how to check that in a minute, what to ask before you book, and what you must be handed when the job is done.
- Search and compare — no account needed
- Nearest to you first
- One score from Google, Trustpilot and Locufy reviews
THE 60-SECOND VERSION
Hiring an extension builder in five steps
- Are you on the Construction Industry Register Ireland, and what is your number?A number you can look up yourself before you agree a price — finishing Touches — finishing work includes plastering, painting, and flooring.
- Will I get a Certificate of Compliance on Completion, and when?On the day the work is finished and tested, not posted on later — utilities Installation — extensions often necessitate the installation or upgrading of utilities such as plumbing, electrical systems, and heating.
- How does materials used change the price?Matching existing materials is dearer than starting fresh. — ask before the quote rather than after.
- How does complexity of the design change the price?The more the brief departs from the usual, the more it costs. — ask before the quote rather than after.
- How does condition of the existing structure change the price?Existing damage has to be made good before the new work goes on. — ask before the quote rather than after.
BEFORE YOU BOOK
Check before you book
Construction Industry Register Ireland (CIRI)
CIRI is a VOLUNTARY register today. The Regulation of Providers of Building Works and Miscellaneous Provisions Act 2022 was signed on 5 July 2022 and S.I. 429/2022 commenced parts of it on 29 August 2022; the Construction Industry Federation was appointed registration body on 16 January 2023. Registration is NOT yet mandatory: the divisions regulations had not been drafted as of a May 2025 Dáil answer, and CIRI itself projects mandatory registration from 2027. So being absent from CIRI breaks no law in 2026 — and being on it is still the only independent check of a builder that exists here.
Search the Construction Industry Register Ireland for the name or the registration number before you agree a price. ciri.ie →
a Certificate of Compliance on Completion
Issued by the assigned certifier and the builder, where the work needed a commencement notice on completion, before the building is occupied. It matters because it is lodged on the statutory register and is what a buyer's solicitor looks for; work done without one surfaces on sale.
Agree before the work starts that you will be handed a certificate of compliance on completion, and keep it with the house papers.
Insurance
Expect public liability and, for anything structural, professional indemnity from whoever designed it. From a company, ask for the insurer, the limit and the VAT number, and ask who actually attends: the team that turns up may be employed, subcontracted or both, and only one of those is supervised by the firm you are paying.
Ask to see the current certificate of insurance — the insurer's name, the limit and the date it runs to.
Trader or private seller
Under the Consumer Rights Act 2022 a trader must tell you they are a trader, and your consumer rights — work carried out with reasonable skill and care, and a cooling-off period on a contract agreed in your home or online — apply to traders and not to private sellers. On Locufy the trader status is shown on the profile.
Look for the trader badge on the Locufy profile, and ask anyone else for it in writing before you agree a price.
VAT
VAT at 13.5%, the reduced rate Revenue publishes for this service. Ask whether the price you were given includes it. A trader under the €42,500 registration threshold does not charge it; one over it must, and must show it separately.
Ask whether the figure you were given includes it, and for the VAT number if they are registered — Revenue publishes the rate for this service. revenue.ie →
A good answer: A number you can look up yourself before you agree a price — finishing Touches — finishing work includes plastering, painting, and flooring.
A good answer: On the day the work is finished and tested, not posted on later — utilities Installation — extensions often necessitate the installation or upgrading of utilities such as plumbing, electrical systems, and heating.
A good answer: Matching existing materials is dearer than starting fresh. — ask before the quote rather than after.
A good answer: The more the brief departs from the usual, the more it costs. — ask before the quote rather than after.
A good answer: Existing damage has to be made good before the new work goes on. — ask before the quote rather than after.
A good answer: Construction Work — the main construction phase includes laying foundations, building walls, and roofing — get the exclusions named in the quote, because a extension builder job is priced on what was agreed and not on what was assumed.
A good answer: Expect public liability and, for anything structural, professional indemnity from whoever designed it — design and Planning — house extensions typically start with design and planning, which may involve an architect or designer to create detailed blueprints.
Getting the quote right
- Materials used — matching existing materials is dearer than starting fresh.
- Complexity of the design — the more the brief departs from the usual, the more it costs.
- Condition of the existing structure — existing damage has to be made good before the new work goes on.
- Construction Work — it determines how long the finished work will last.
- In writing before anyone starts — a message on Locufy counts
- What is NOT included, named
- Who actually attends, and whether they are employed or subcontracted
- The VAT number, and whether it checks out on the Revenue register
Walk away if
- They are not on the Construction Industry Register Ireland, or the number does not resolve to the name on the quote
- No a Certificate of Compliance on Completion is offered, or you are told you do not need one for work of this kind
- They will not talk about it: materials used — matching existing materials is dearer than starting fresh
- They will not talk about it: complexity of the design — the more the brief departs from the usual, the more it costs
- They will not talk about it: condition of the existing structure — existing damage has to be made good before the new work goes on
- A price for the extension builder before anyone has asked the size, the access or the condition of what they are working on
What an extension builder costs: €2,500–€4,500 per m²
The figures are for the job, per m², and a quote for your own is the only number that binds anyone. Single-storey extension and Double-storey extension each carry their own band. House Extension price guide →
Guide prices compiled by the Locufy team from published Irish and UK provider price lists and 2026/27 cost guides. Updated 2026.
KNOW WHAT TO LOOK FOR? NOW FIND ONE
Extension builders near you, with the badges that matter shown
ID checked, trader status and one score from every review — on the card, before you message anyone. Nearest first. No account needed to look.
Or post the job free and let them come to you.
- Look firstMaterials used — matching existing materials is dearer than starting fresh — that is what the extension builder is judging on the first visit, and a price given without it is a guess.
- Agree what is being doneComplexity of the design — the more the brief departs from the usual, the more it costs — put in writing before anyone starts, because it is the document you both read back at the end.
- The work itselfCondition of the existing structure — existing damage has to be made good before the new work goes on — and anything found on the day that was not in that is priced before it is started.
- Check it togetherConstruction Work — it determines how long the finished work will last — walked against the written scope rather than against the feeling of it, while the extension builder is still there.
- What you are handedA Certificate of Compliance on Completion, the invoice and any guarantee on the workmanship and the parts, check local building regulations and required permits before starting the project.
- Design and Planning
- House extensions typically start with design and planning, which may involve an architect or designer to create detailed blueprints.
- Construction Work
- The main construction phase includes laying foundations, building walls, and roofing.
- Utilities Installation
- Extensions often necessitate the installation or upgrading of utilities such as plumbing, electrical systems, and heating.
- Finishing Touches
- Finishing work includes plastering, painting, and flooring.
- Single-Storey Extension
- This involves adding a new room at ground level, often to create a larger living area or kitchen.
- Double-Storey Extension
- A two-level extension that provides additional rooms on both the ground and first floors, ideal for larger families.
AFTER
When the job is done
Hiring an extension builder: questions people ask
The cost of a house extension can vary significantly based on size, complexity, materials used, and location. For example, a more complex design or high-end materials will increase overall costs.
The duration of a house extension project can range from a few weeks to several months, depending on the size and complexity. A simple single-storey extension might take around 6-8 weeks, while larger projects could take longer.
Yes, many homeowners choose to combine related jobs, such as a house extension and renovation of existing rooms. This can often lead to cost savings and a more streamlined project timeline.
Emergency work for house extensions is generally limited and depends on the nature of the issue. Most projects require careful planning and scheduling, so same-day availability is uncommon.
Out of scope work may include landscaping, interior decorating, or any structural changes not covered in the original design. Homeowners should clarify with contractors what is included in the initial agreement.
Search the name or the registration number. If the number does not resolve to the name on the quote, stop there.
MORE GUIDES
More hiring guides in trades & construction
Extension builders near you
Sources — checked October 2026
- Regulation of Providers of Building Works and Miscellaneous Provisions Act 2022
- S.I. 429/2022 — Commencement Order
- Construction Industry Register Ireland
- Department of Housing — Building Control
- Consumer Rights Act 2022
- Revenue — BUILDING and CONSTRUCTION SERVICES (Private dwellings and Non-residential immovable goods) — Reduced rate
- Revenue — current VAT rates (effective 1 January 2026)
- Revenue — VAT thresholds: €42,500 for a person supplying services only