How Much Does A New Extension Cost?

We know that budget is a key factor when planning your kitchen extension, and while costs can vary—especially in Ireland—we’re here to give you a clear starting point. Our Extension Cost Calculator provides an estimated price range based on your specifications, helping you understand what’s possible within your budget.

  • Explore your options – Discover different extension styles tailored to your home.
  • Get a realistic cost estimate – Understand key factors that impact pricing.
  • Visualize your space – Our 3D models bring your extension to life before construction even begins.

While this tool doesn’t replace a detailed consultation, it’s a great way to get a ballpark figure and start planning with confidence.

Try our cost calculator today and take the first step toward your dream home!

House Type

Select from the below options

Detached

Semi-detached

End of Terrace

Terraced - Flat Back

Terraced - L Shaped

Extension Type

Select from the below options

Rear Extension

Side Extension

Wraparound Extension

Roof Type

Select from the below options

Flat Roof

Crown Roof

Gable Roof

Pitched Roof

Pitched (HIP) Roof

Your example costs:

All estimated costs for house extensions include building work, plumbing, electricity, glazing, external doors and applicable VAT.

Flat Roof

Small Rear Extension

Estimated Cost:

€ 60,000

Flat Roof

Medium/Large Rear Extension

Estimated Cost:

€ 90,000

Crown Roof

Medium/Large Rear Extension

Estimated Cost:

€ 100,000

Flat Roof

Large Side & Rear Extension

Estimated Cost:

€ 150,000

Crown Roof

Large Side & Rear Extension

Estimated Cost:

€ 160,000

Gable Roof

Large Wrap Around Extension

Estimated Cost:

€ 110,000

flat roof

Large Wrap Around Extension

Estimated Cost:

€ 115,000

Pitches (HIP) Roof

Large Wrap Around Extension

Estimated Cost:

€ 124,000

Gable Roof

Medium Wrap Around Extension

Estimated Cost:

€ 105,000

flat roof

Medium Wrap Around Extension

Estimated Cost:

€ 100,000

Pitches (HIP) Roof

Medium Wrap Around Extension

Estimated Cost:

€ 105,000

Gable Roof

Small Wrap Around Extension

Estimated Cost:

€ 110,000

flat roof

Small Wrap Around Extension

Estimated Cost:

€ 100,000

Pitches (HIP) Roof

Small Wrap Around Extension

Estimated Cost:

€ 105,000

flat roof

Large Side Return

Estimated Cost:

€ 90,000

Pitche Roof

Large Side Return

Estimated Cost:

€ 95,000

flat roof

Medium Side Return

Estimated Cost:

€ 80,000

Pitche Roof

Medium Side Return

Estimated Cost:

€ 85,000

flat roof

Small Side Return

Estimated Cost:

€ 70,000

Pitched Roof

Small Side Return

Estimated Cost:

€ 75,000

flat roof

3m x 3m Rear Extension

Estimated Cost:

€ 55,000

Pitched Roof

3m Rear Extension

Estimated Cost:

€ 85,000

Gable Roof

3m Rear Extension

Estimated Cost:

€ 95,000

flat roof

3m Rear Extension

Estimated Cost:

€ 90,000

Crown Roof

3m Rear Extension

Estimated Cost:

€ 100,000