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Design, Cost & Planning

Granny Flat Dublin: Know the Cost Before You Commit

Add a private, self-contained home for a parent, an adult child or rental income, without moving house. Most granny flats in Dublin need planning permission and costs vary a lot by size. We tell you your likely cost and whether you need permission before you spend a euro on design.

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  • Built on-site to full home standard, not a modular pod
  • Your planning position confirmed before any drawings
  • Every build certified by an Independent Chartered Engineer
  • Complete builds from a minimum project value of €100,000

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All enquiries are reviewed by our team before a consultation is confirmed.

CIRI Registered

Construction Industry Register Ireland

5★ Google Rated

Verified by Dublin homeowners

CIF Member

Construction Industry Federation

100+ Projects Delivered

Across Greater Dublin Region

Understand Your Cost and Planning Before You Start

Two things decide your whole project: what your granny flat will cost, and whether it needs planning permission. We confirm both first, using real construction cost data and a check against current planning rules. You get a clear budget and a clear path before anyone draws a line.

As a general market guide for a self-contained granny flat in Ireland

  • Compact studio, around 25 sqm: from about €65,000 plus VAT
  • One-bed, around 35 to 40 sqm: from about €82,000 plus VAT
  • Larger two-bed annexe: up to about €130,000 all-in
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Client Reviews

What Our Clients Say

Rated 5★ across Google, Houzz, and OnlineTradesmen by Dublin homeowners.

★ ★ ★ ★ ★
GB
Graham Barry
Google

"Professional, reliable service with clear communication and integrity."

"Professional, reliable service with clear communication and integrity. The team kept us informed at every stage and delivered exactly what was promised. Would recommend to anyone looking for a trustworthy provider."

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★ ★ ★ ★ ★
KW
Kirsten Wendenburg
Google

"Excellent communication and budget-friendly suggestions throughout."

"Excellent communication and budget-friendly suggestions throughout. They took the time to understand our needs and offered practical options at every step. The end result exceeded our expectations."

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★ ★ ★ ★ ★
OA
Olga Antipenko
Google

"Excellent communication and support throughout. Highly recommend."

"Excellent communication and support throughout. Highly recommend. From the first call to the final handover everything was handled professionally. The team was responsive, knowledgeable and clearly cared about the outcome."

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★ ★ ★ ★ ★
JM
James Murphy
Google

"Outstanding work from start to finish. Couldn't be happier with the result."

"Outstanding work from start to finish. Couldn't be happier with the result. They were punctual, tidy and clearly took pride in their craft. The whole project came in on time and on budget."

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★ ★ ★ ★ ★
SO
Sarah O'Brien
Google

"Genuinely impressed with the quality and attention to detail."

"Genuinely impressed with the quality and attention to detail. Every aspect of the project was carefully considered and the finish is excellent. I'd use them again without hesitation."

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★ ★ ★ ★ ★
DK
David Kelly
Google

"Top-class service. Friendly team and a fair price."

"Top-class service. Friendly team and a fair price. They were upfront about everything, no hidden surprises and the work was completed to a very high standard. Already recommended them to a neighbour."

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Your Whole Granny Flat Build, Managed from Start to Finish

Your Dublin granny flat is built on-site to the same standard as a permanent home: solid foundations, full insulation, and its own kitchen, bathroom and front door. It lasts, and it adds real value to your property. One project manager runs the whole build, so you have a single point of contact from the first feasibility consultation to final sign-off.

You see every drawing, cost and update in your client portal, even from abroad, and the finished build is certified by an Independent Chartered Engineer.

  • Own-door and fully self-contained for day-to-day independence
  • Built to building regulations and warm enough for year-round living
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Not sure what your home renovation will cost? We give you full cost clarity before you commit to anything.

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0818 333 443
How It Works

A Structured Process Built Around Your Budget

BuildTech follows a clear four-step pathway, from initial feasibility through to completed construction, designed to protect your budget and keep your project on track.

1

Feasibility

Budget & scope clarity before any design work begins

Design

Measured survey, technical layout & cost plan
2
3

Planning

Managed application where required, many extensions are exempt

Build

On-time, on-budget delivery with full project management
4
Start with a Feasibility Call
Why BuildTech

Why Choose BuildTech for Your Granny Flat?

As specialist granny flat builders in Dublin, we give you budget certainty before design, one project manager for the whole build, and full chartered-engineer certification. We build permanent, certified granny flats, and we tell you what is realistic before you spend, so you are not left with drawings you cannot afford to build.

We are a member of the Construction Industry Federation, registered with the Construction Industry Register Ireland, and accredited by the Chartered Institute of Building.

  • Real cost data at feasibility, so the budget holds
  • Fixed and transparent pricing, no surprises mid-build
  • Client portal with drawings, costs and updates
  • Every build certified by an Independent Chartered Engineer

Our Granny Flat Planning Process in Dublin, Step by Step

Most self-contained granny flats need planning permission because a unit with its own kitchen, bathroom and entrance counts as a separate dwelling. We manage the full application, so you do not have to deal with the council yourself.

We check whether you need permission

First, we work out whether your granny flat needs planning permission at all. A self-contained space with its own kitchen, bathroom and door is usually treated as a separate home, so it needs an application. Knowing this early protects both your budget and your timeline.

We shape the design to fit the rules

Next, we design your granny flat to fit your council’s rules on height, spacing and the impact on neighbours. Where it helps, we raise the plan with the planning office early, so anything likely to draw an objection is sorted out before you apply.

We prepare the drawings and paperwork

Our in-house architectural design team then prepares the full set of drawings and supporting documents your application needs. Getting this right the first time keeps things moving, because gaps are the main reason a council stops to ask for more information.

We submit and manage the application

We submit the application to your local authority and manage it from there, including any queries the planners raise. You follow it all through your client portal, so you always know where your granny flat stands without chasing anyone.

We see it through to the decision

A planning decision usually takes a couple of months, though this varies by council and by site. When it arrives, we explain any conditions in plain terms and move your granny flat to the next stage: detailed costing and design, or straight to build.

Common Issues

What Causes Granny Flat Planning Delays or Refusals?

Most refusals and delays are avoidable. For granny flats in Dublin, they nearly always come down to four things:

Getting the classification wrong

Treating a self-contained flat as an exempt extension. If it has its own kitchen, bathroom and entrance, the council usually sees a separate home that needs permission.

Incomplete or inaccurate drawings

Drawings that miss detail, use the wrong scale, or leave out site information. These prompt the council to pause and ask for more, which adds weeks.

A design that clashes with local policy

A design at odds with the local development plan, on height, scale or overlooking. It invites objections from neighbours or conditions from the planners

Skipping the early council conversation

Applying cold, without testing the idea with the planning office first. An early chat often surfaces problems while they are still cheap and easy to fix.

Attached, Standalone or Subdivision: Which Granny Flat Needs Planning?

Most self-contained granny flats need planning permission. The safest move is to settle your classification at feasibility, before any drawings, so you know exactly where you stand. Always confirm with your local authority too.

What matters is how yours is built:

  • Attached extension: a rear extension up to 40 sqm can be exempt, but adding a self-contained unit usually tips it into needing permission.
  • Standalone in the garden: a separate unit with its own kitchen, bathroom and door is treated as a separate home, so it needs permission.
  • Splitting your home: dividing your house into a self-contained unit also needs permission under current rules.

Ready to build a granny flat?

Start with a feasibility consultation. We confirm your budget and planning position before any design begins, so you know exactly where you stand. Book online or call 0818 333 443.

Request A Feasibility Consultation
Common Questions

Frequently Asked Questions

Usually, yes. A self-contained unit with its own kitchen, bathroom and entrance is a separate dwelling and generally needs permission. An attached extension under 40 sqm can sometimes be exempt. We confirm your exact position at feasibility.
As a general market guide, from about €65,000 plus VAT for a compact 25 sqm studio, around €82,000 plus VAT for a 35 to 40 sqm one-bed, and up to about €130,000 all-in for a larger two-bed. These are market figures, not a BuildTech quote. Your cost depends on size, specification and site. BuildTech's minimum project value is €100,000.
Allow roughly 8 to 12 weeks for planning, then a build period that depends on size and specification. We give you a realistic timeline at feasibility.
A typical granny flat takes 16 to 24 weeks from construction start to completion, depending on size and complexity. Where planning permission is required, allow an additional 8–12 weeks from submission to decision. BuildTech provides a full project programme at the cost and technical design stage.
€100,000. We build complete, certified granny flats and whole-home projects, not small cosmetic jobs or modular pods.

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We review your enquiry before confirming a consultation — ensuring only suitable projects proceed.

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  • Min. project €100k · No surprises

What's Included

  • Feasibility consultation included
  • Measured survey & assessment
  • Technical design package
  • Full project management
  • Engineer certification on completion

Related Services

Home Renovation

House Extension

Attic Conversion

Deep Retrofit

Feasibility Consultation

Not sure where to start?

A feasibility consultation (€200 call · €500 home visit) confirms your planning position before you spend anything on drawings.

Book Feasibility Call
Explore more

Our Services

BuildTech is a specialist design and build contractor. We take on a focused range of projects — and we do not progress any project without a clear, agreed budget.

Single-Storey Rear Extension

The most common home project in Dublin. Open-plan kitchen and living, utility room, or additional family space — from feasibility through to a certified, compliant build.

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Home Renovation

Whole-home renovations and structural alterations for Dublin homeowners. Internal reconfigurations, layout redesign, and full refurbishment — all budget-led from day one.

Learn More

Feasibility Consultation

€200 call or €500 home visit. We establish what is realistically achievable within your budget before any design work begins — saving you time, money, and stress.

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Planning Permission

Full application management — pre-planning strategy, drawings, submission, and decision monitoring. Many extensions are planning exempt; we confirm this first.

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Already Have Plans?

Cost Planning & Construction Review from €2,500 + VAT. We provide a full cost breakdown of your existing drawings — gap identification, budget alignment, and value engineering.

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Cost & Technical Design

Measured survey, technical layout, and a detailed cost plan — all aligned to your budget before construction begins. No over-specified designs that cannot be built within your means.

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Our work

Recent Projects

Each project below started with a feasibility consultation and a clear budget. Here is what we delivered.

All Projects

Extension + Renovation

Full Ground Floor Renovation with Rear Extension

Location : Dublin

Scope : Ground floor knock-through, rear extension, open-plan kitchen and living

Status : Planning exempt

✓ Delivered on time and on budget

Extension + Renovation

Sandymount Seafront
Renovation

Location : Sandymount, Dublin 4

Scope : Full home renovation of period seafront property

Status : Planning exempt

✓ Full project management, completed on programme

Extension + Renovation

Rear Extension Plus Partial Renovation, Dublin 14

Location : Dublin 14

Scope : Single-storey rear extension and partial ground-floor renovation

Status : Planning exempt

✓ On budget, handover on schedule

Extension + Renovation

20 sqm Single-Storey Rear Extension, Mount Merrion

Location : Mount Merrion, South Dublin

Scope : 20 sqm flat-roof rear extension, open-plan kitchen and dining

Status : Planning exempt

✓ Completed on time and on budget

Extension + Renovation

Split-Level Open Plan Kitchen & Lounge Renovation

Location : Dublin

Scope : Structural reconfiguration, split-level open-plan kitchen and lounge

Status : Planning exempt

✓ Full project management included

Ready to Build a Granny Flat?

Start with a feasibility consultation. We confirm your budget and planning position before any design begins, so you know exactly where you stand. Book online or call 0818 333 443.

 

Request a Consultation →
0818 333 443

No obligation. No pressure. Just honest advice.