10 house extension ideas for every budget that add space and value
Are you are looking for house extension ideas, but are not sure on how much does a house extension cost in Ireland or maybe what the best option is for your needs? We'll take you through 10 different house extension ideas while outlining an expected budget and what the extension is most suitable for.
1. Single-Storey Rear Extension
Best for: Extra kitchen or dining space | Budget range: €30,000 – €60,000
The single-storey rear extension is the most popular choice for Irish homeowners and it's easy to see why. By pushing out from the back of your home you can dramatically open up your ground floor creating a larger kitchen, a spacious dining area or a bright family room.
This type of extension works particularly well with older semi-detached and terraced homes that have a standard kitchen layout at the rear. When combined with bi-fold or sliding doors opening onto the garden, it creates a seamless indoor-outdoor living experience that's hugely appealing to buyers.
Value added: A well executed rear extension can add 10–15% to the value of your home.
2. Two-Storey Extension
Best for: Multiple new rooms, bedroom + living space | Budget range: €60,000 – €120,000
If you need more space but your site footprint is limited, building upwards is the logical next step. A two-storey extension gives you double the floor area for a fraction of the cost of two separate builds making it one of the best value for money options available.
Typically, the ground floor adds a new living or family room, while the upper storey creates an additional bedroom or a luxurious master suite with ensuite bathroom. This is particularly popular with families in Dublin and larger urban areas where space is at a premium.
Value added: A two-storey extension can add 20–25% to your property's value, particularly in high demand areas like Dublin.
3. Side Return Extension
Best for: Narrow side passages on terraced or semi-detached homes | Budget range: €25,000 – €55,000
Many homes have a narrow largely unused passage running down one side of the property. A side return extension fills in this dead space to widen your ground floor, most often transforming a cramped kitchen into a stunning open plan kitchen diner.
By adding a roof light above and extending the kitchen out to the side, you gain both width and natural light two things that make an enormous difference to daily living.
Value added: In the right property type a side return can add up to €20,000 – €30,000 to resale value and is an excellent selling feature.
4. Wrap-Around Extension
Best for: Maximum ground-floor transformation | Budget range: €70,000 – €130,000
For homeowners who want to make a real statement, the wrap-around extension combines a rear extension with a side return to create an L-shaped addition that wraps around the back corner of the house. The result is a dramatically enlarged ground floor with excellent flow and light.
This is one of the most transformative options available as it completely transforms the layout of your home's ground floor by creating a large, modern open plan living space that feels entirely new. It's a particularly popular choice among homeowners who have purchased older homes with dated layouts and want to modernise without moving.
Value added: Wrap-around extensions consistently add significant value and are a major selling point, often returning close to the full cost of the build in added property value.
5. Attic Conversion
Best for: Adding a bedroom or home office without extending outward | Budget range: €20,000 – €45,000
An attic conversion is one of the most cost effective ways to add a usable room to your home. Rather than extending your footprint, you're making use of a space that already exists, typically a largely wasted roof space and turning it into a bright functional room.
Common uses include a fourth or fifth bedroom, a home office or a playroom. When a proper staircase, insulation, windows and flooring are added, a converted attic can feel like a genuinely premium space.
Value added: A converted attic with bedroom and ensuite can add 15% or more to your home's value.
6. Garage Conversion
Best for: Homes with an integrated or attached garage | Budget range: €15,000 – €35,000
If you're lucky enough to have an attached garage converting it into a habitable room is one of the most affordable ways to gain significant living space. Because the structure already exists, the work mainly involves insulation, flooring, windows and internal finishes, keeping costs well below what a new build extension would require.
Garage conversions are commonly used to create a home office, a playroom, a utility/laundry room, a ground floor bedroom or a self-contained space.
Value added: Garage conversions are among the highest return on investment options with potential to add 10–15% to property values.
7. Sunroom or Garden Room
Best for: Extending your living space with natural light | Budget range: €15,000 – €40,000
A sunroom or glazed garden room is a popular and relatively affordable way to extend your home while maintaining a strong visual connection to the garden. A good sunroom can be used year round when properly insulated and heated.
This option is especially attractive for those on a tighter budget who still want a meaningful increase in usable space.
Value added: A quality sunroom adds kerb appeal and living space typically returning €10,000 – €20,000 in added value.
8. Over-Garage Extension
Best for: Detached garages with space above | Budget range: €40,000 – €75,000
If you have a detached or integral garage with a flat or pitched roof building above it is an often overlooked way to add an entirely new room or suite. The space created can serve as a master bedroom with ensuite, a self-contained apartment for a family member or a generous home office.
This type of extension requires careful structural assessment to ensure the existing garage foundations and walls can take the additional load so engaging an experienced builder and structural engineer from the outset is essential.
Value added: Over-garage additions are highly valued by buyers looking for flexible living arrangements and can add 10 – 20% to property value.
9. Granny Flat or Garden Lodge
Best for: Self-contained living space in the garden | Budget range: €50,000 – €100,000
With housing demand on the rise in Ireland and rental income an attractive prospect for many homeowners, a self-contained garden lodge or granny flat is an increasingly popular option. Built in the garden as a separate structure it can accommodate an elderly parent, an adult child or serve as a rental unit.
Value added: In addition to rental income potential a well built granny flat can add €30,000 – €70,000 to your property's overall value and significantly broaden its appeal.
10. Open Plan Kitchen Diner Extension
Best for: Modern family living and maximum lifestyle impact | Budget range: €40,000 – €80,000
If there's one extension that consistently tops wish lists in Ireland right now, it's the open plan kitchen diner living room. This project typically combines a rear extension with internal reconfiguration removing walls between the kitchen, dining room and sometimes living room to create one large sociable light filled space.
The result is the kind of layout that defines modern family living: a kitchen where parents can cook while keeping an eye on the kids, a dining space for everyday meals and entertaining and a living area that flows seamlessly into the garden. When done well it completely transforms how a home feels and functions.
Value added: An open plan ground floor is one of the most desirable features among Irish home buyers and can add 15 – 20% to your home's market value.
Ready to Extend Your Home?
No matter what your budget or your vision, the right extension can transform the way you live and add real lasting value to your property. As experienced Dublin house extension builders, we've helped homeowners create the spaces they've always dreamed of.
Call today or get in touch today for a free, no obligation consultation and quote. We'd love to help you make it happen.