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Home Extensions in Dublin
Add the space your home is missing — a bigger kitchen, a family room, another bedroom — delivered on time and on budget.
One team handles your whole extension, from first plans to a certified handover. Single-storey, two-storey and wrap-around extensions, across Dublin and Greater Dublin for over a decade.
No obligation. We reply within one working day.
Request a Quote
Tell us about your extension and we’ll come back with guide costs and the next step.
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5★ rated by Dublin homeowners
Request a Quote
Tell us about your extension and we’ll come back with guide costs and the next step.
Why Do Home Extensions So Often Go Wrong?
Because the real cost only surfaces once the work has started, and the trades building it answer to no one on site.
What usually happens
1
Priced blind. You commit before the real cost is known, so the budget moves once work starts.
2
Passed between trades. Waits on subcontractors the builder cannot schedule, and stalls.
3
Handed back unfinished. Snags and the tie-in drag on, or the job is left incomplete.
With Alder
1
Priced up front. A clear cost before you commit, with no moving-target surprises.
2
Built by our own team. Our own trades do the work, so your extension keeps moving.
3
Finished and certified. One team from the first block to handover, tie-in included.
- Cost estimator
What Will Your Extension Cost?
Get a realistic Dublin extension price range in about a minute, before speaking to anyone.
The estimate uses real local costs and the biggest price factor: how much of your existing house the new space needs to open up and connect into.
Home Extensions We've Built in Dublin
Real extension projects, each one started with a set budget and finished by our own team.
Dublin
Ground-floor extension and full renovation
Work
Rear extension in high-performance cavity walls with upgraded insulation and an integrated rooflight, plus renewed services across the ground floor.
Result
Delivered to the price agreed up front by a single in-house team.
Dublin 14
Rear extension and kitchen-living reconfiguration
Work
Single-storey rear extension opened into a fully reworked kitchen and living are
Result
Held to the price agreed up front, from first block to handover.
Swords
Rear extension and renovation, five-bed home
Work
Rear extension combined with a whole-home renovation on a larger family property.
Result
One team managing the full scope, delivered on budget.
How Much Does a Home Extension Cost in Dublin?
A home extension in Dublin usually costs between €2,500 and €3,500 per square metre to build.
What you pay comes down to the size, the finish, and how much of the existing house has to be opened up and tied into the new space. Engineering fees are separate, and these are guide ranges, not a fixed quote.
The biggest variable is the existing house: the more it has to be opened up and reconnected, the higher the rate. We turn these ranges into an exact price for your extension before you commit.
Recent Home Extensions in Dublin
Extensions we have built across Dublin and Greater Dublin.
- FAQ
Home Extension Questions, Answered
Planning, cost, timelines and living through the build — the questions Dublin homeowners ask us most.
Often not. A single-storey rear extension is generally exempt if it adds no more than 45 m² (counting previous extensions), leaves 25 m² of open space to the rear, and stays below the existing roofline. The 45 m² limit applies from July 2026, up from 40 m². We confirm exactly where your property stands when we visit.
As a build guide, expect €2,500 to €3,500 per square metre. Where you land depends mainly on the tie-in to the existing house, plus finish and access. Engineering fees are separate, and a visit gives you an exact figure before you commit.
A single-storey rear extension typically takes 12 to 20 weeks on site, depending on size and complexity. Where planning permission is required, allow a further 8 to 12 weeks before construction can begin. You receive a detailed programme before the build starts.
That is a decision we make with you before the build. An extension can be detailed to blend seamlessly with the original house or set up a deliberate contrast in materials and glazing. Either way, the junction between old and new is where the technical detailing matters most, and it is handled by the same team building the rest.
In many cases yes, especially for a rear extension where the house stays largely intact until the connection is made. Where occupied rooms are involved, we plan the sequence and any temporary arrangements with you up front.
Find Out What Your Extension Will Cost
Tell us about your extension and get a clear price.
We come back with a realistic cost for your extension and the next step. If it is the right fit, you get one team from your first visit through to a finished, certified space.
Dublin and Greater Dublin · minimum project value €100,000 · no obligation.
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Unit U1 Trenure Enterprise Center 17
Rathfarnham Road Dublin D6W X921
01 912 0306 · © 2026 Alder Construction
01 912 0306 · © 2026 Alder Construction