Dublin House Extensions : A Complete Guide
At Rejig Architects, we specialise in house extensions, attic conversions, and residential renovations across Dublin. We help homeowners create brighter, more functional homes through thoughtful design, planning permission support, and detailed architectural drawings.
Planning a House Extension in Dublin
Planning a house extension in Dublin can transform how your home works while allowing you to remain in the area you already know and enjoy. Whether you are extending for additional family space, improving energy efficiency, or reconfiguring an outdated layout, understanding the process early can save significant time and cost.
Why Extend Instead of Move?
A well-designed extension can:
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Add usable space
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Improve natural light
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Enhance connection to the garden
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Increase energy efficiency
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Improve property value
Common projects include:
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Rear extensions
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Side extensions
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Attic conversions
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Full refurbishments
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Energy retrofit projects
Exempted Development
Some house extensions in Ireland can be built without planning permission under exempted development rules.
Typically, rear extensions may be exempt where:
Total additional floor area does not exceed 40m²
Sufficient private garden space remains
Height restrictions are respected
Overlooking issues are avoided
Professional advice is recommended before starting work, particularly where previous extensions already exist.
When Is Planning Permission Required?
Planning permission is generally required where:
Extensions exceed exempted development limits
Significant roof alterations are proposed
The property is a protected structure on in an Architectural Conservation Area
The proposal affects neighbouring properties
Typical planning applications include:
Existing and proposed drawings
Site maps
Planning notices
Supporting documents
What Will My Extension Cost?
Construction costs in Dublin vary depending on specification, structural complexity, and the condition of the existing house.
Typical Construction Costs
Standard extensions: €3,500–€4,500/m²
High-spec refurbishments: €2,000+/m²
Additional Costs
Professional fees
Kitchens and finishes
Energy upgrades
Landscaping
Contingency allowances
A quantity surveyor can help monitor construction costs throughout the project, ensuring the design remains aligned with the agreed budget and reducing the risk of unexpected overspend.
How Long Will It Take?
01
Initial Design
2-4 weeks
Early design stage exploring layout options, spatial planning, and overall project brief.
03
Planning Process
12 weeks
Statutory assessment period by the local authority following submission of the planning application.
05
Tender
4-6 weeks
The tender process aims to find the best value contractor for the project through the comparison of like-for-like costings.
02
Concept Design
6-8 weeks
Preparation of drawings and documents required for a planning application or exempted development review.
04
Technical Design
8-12 weeks
Detailed construction drawings and coordination information prepared for pricing, compliance, and construction.
06
Construction
4-9 months
On-site building works including extension, renovation, fit-out, and completion.
Why Hire An Architect?
An architect helps guide a project from early ideas through planning, technical design, and construction. Working with an architect from an early stage can help with :
Developing layouts that improve how the home functions day-to-day
Maximising natural light, views, and connection to the garden
Establishing a realistic budget from the outset
Identifing planning risks and opportunities early
Producing detailed drawings for planning and construction
Coordinating engineers, quantity surveyors, and consultants
Helping to reduce costly mistakes and design changes on site
Advising on materials, energy performance, and sustainability
Balancing aesthetics, practicality, and buildability
Improving long-term property value through better design
Good architecture is not simply about adding floor area, but about creating homes that feel brighter, calmer, more functional, and better suited to everyday life.
Common Mistakes to Avoid
Underestimating Costs
Budgets often overlook wider refurbishment works and contingencies.
Proceeding Without Detailed Drawings
Incomplete information can lead to delays, disputes, and unexpected costs.
Prioritising Size Over Quality
Natural light, layout, and circulation are often more important than raw floor area.
Ignoring Energy Performance
Extensions work best when considered alongside upgrades to the existing house.
Thinking About Extending Your Home?
At Rejig Architects, we specialise in house extensions, attic conversions, and residential renovations across Dublin.
We work with homeowners from initial concept design through planning permission and technical construction drawings to create carefully considered homes that feel brighter, more functional, and more energy efficient.
If you are planning for a house or extending or refurbishing your home and would like to discuss your project, please do get in touch.