Granny Flat, Garden Room, or Modular
Home: What’s the Difference?
Short answer: which do you need?
- Garden room: Extra space for office, gym, studio, or storage; not a separate
- Granny flat: Self-contained family accommodation, often linked to the main
- Modular home: A complete, independent dwelling to full residential
Your choice depends on how you plan to use the space and whether you need a separate home or just extra rooms.
What is a garden room?
A garden room is typically:
- A single-storey structure in your garden
- Used as an office, gym, studio, hobby space, or storage
- Not intended as a separate dwelling (no full kitchen/bedroom setup)
Many garden rooms can be built under exempted development rules if they meet specific size, height, and use conditions. They’re popular for:
- Home offices
- Gyms and yoga studios
- Music or art rooms
- Additional storage or workshop space
What is a granny flat?
A granny flat is:
- A self-contained living space for family members
- Often includes a bedroom, bathroom, and small kitchen or kitchenette
- Usually attached to or within the main house, but can be a separate unit
Planning rules depend on how it’s configured and whether it’s considered a separate dwelling. Granny flats are often used for:
- Elderly parents or relatives
- Adult children saving for their own home
- Carers or live-in support
What is a modular home?
A modular home is:
- A complete, factory-built dwelling
- Designed to full residential standards (BER, fire, etc.) Modular Homes Ireland – 2026 Blog Collection
- Intended as a primary or secondary home, not just an extra room
It can be placed on its own site or as a second dwelling on an existing property (subject to planning). Uses include:
- A new main home on a rural or infill site
- A second home for family or rental
- A long-term investment property
Key differences: use, planning, and cost
Use
- Garden room: Non-residential extra
- Granny flat: Family accommodation, often linked to the main
- Modular home: Independent dwelling for full-time
Planning
- Garden room: Often exempt if within size and use
- Granny flat: May or may not need planning depending on configuration and whether it’s a separate dwelling.
- Modular home: Planning usually required as it’s a new
Cost
- Garden room: Typically the lowest cost
- Granny flat: Mid-range, depending on size and
- Modular home: Higher cost, but delivers a full, independent
Which is right for you?
Ask yourself:
- Do I need a separate home or just extra space?
- Will anyone live there full-time?
- Do I need a kitchen and bathroom, or just a room?
- What’s my budget and planning situation?
- Choose a garden room for an office, gym, or
- Choose a granny flat if you need family accommodation connected to your main
- Choose a modular home if you want a fully independent, modern
FAQs: granny flat, garden room, or modular home
Can I rent out a granny flat or modular home?
Potentially, yes, but it depends on planning permission and local policies. Some councils allow secondary dwellings for family or rental; others are more restrictive.
Do I need planning for a garden room?
Many garden rooms are exempt if they meet specific conditions on size, height, and use. Once you add sleeping accommodation or a full kitchen, planning is more likely to be required.
Which option adds the most value?
A well-designed modular home or granny flat can add significant value by creating additional living space or income potential. Garden rooms add value mainly through improved functionality (e.g., Modular Homes Ireland – 2026 Blog Collection home office).
Next steps
If you’re unsure which option suits your site and goals, we can review your property and outline the most suitable solution for your needs and budget.
