One of the first questions homeowners ask when planning an extension is: “How much will it cost?”
The honest answer is: it depends, but there are realistic cost ranges you should understand before proceeding.
▶ This article outlines typical house extension costs in Dublin, what drives price changes, and how to budget properly.
Typical House Extension Costs in Dublin
As a broad guide (2025 prices):
- Single-storey extension: €2,300 – €3,000 per m²
- Two-storey extension: €2,000 – €2,700 per m²
- High-spec / complex projects: €3,000+ per m²
These figures usually include structure and finishes but exclude professional fees, VAT, and abnormal site conditions.
What Drives Extension Costs?
Key cost drivers include:
- Size and layout
- Specification level (windows, finishes, kitchens)
- Ground conditions and drainage
- Structural alterations to the existing house
- Access and site constraints (very common in Dublin)
Small design changes can have a significant cost impact if not assessed early.
Costs Homeowners Often Forget
Commonly missed items include:
- Demolition and enabling works
- Upgrades to existing electrics or plumbing
- Temporary works and protection
- Landscaping and external works
- VAT and professional fees
These omissions are a major reason projects exceed budgets.
How a Quantity Surveyor Helps
A Residential Quantity Surveyor provides:
- A realistic early cost plan
- Cost comparisons for design options
- Independent tender review
- Ongoing cost control during construction
This allows you to proceed with clarity rather than assumptions.
👉 Residential Quantity Surveyor
👉 Quantity Surveyor Dublin
Final Thoughts
Before committing to an extension, invest time in understanding the true construction cost. Early cost advice often saves far more than it costs.