A conservatory-style extension in Ireland can cost from roughly €2,200 to €2,500 per m² for a basic finish, while a more highly specified glazed extension can reach €3,500 to €5,000 per m². These are early budgeting figures based on OS Holding’s current extension cost guidance, not a fixed quotation. Your final price will depend on the structure, glazing, roof, ground conditions, access, finishes and whether professional or planning fees are included.
OS Holding designs and builds extensions across Dublin and surrounding areas. A site survey is the best way to confirm what is practical for your home and receive a properly itemised quotation.
How Much Does a Conservatory Extension Cost in Ireland?
The figures below convert our current per-square-metre extension guidance into indicative project allowances. They are useful for early planning, but every conservatory is priced to its design and site conditions.
| Example size | Basic finish | High-spec glazed finish |
|---|---|---|
| 12 m² | €26,400 to €30,000 | €42,000 to €60,000 |
| 20 m² | €44,000 to €50,000 | €70,000 to €100,000 |
Indicative calculations only. Planning, design, structural engineering and other professional fees may be separate. VAT and exclusions should always be confirmed in writing.
What Affects the Cost of a Conservatory Extension?
Size and shape
A compact rectangular design is generally simpler to build than a large or unusually shaped room. The amount of structural work required to connect the new space to the existing house also matters.
Glazing and frame specification
Frame material, glass performance, opening panels, sliding or bi-fold doors and solar-control requirements can make a substantial difference to the price. Good thermal performance is especially important if you want a room that is comfortable throughout the year.
Roof design
A fully glazed roof, solid insulated roof, hybrid roof or roof lantern will each have a different structural build-up and cost. The best option depends on daylight, heat control, appearance and how you plan to use the room.
Ground conditions and access
Foundation depth, drainage, restricted side access, excavation and waste removal can all affect labour and plant costs.
Heating, electrics and finishes
Underfloor heating, radiators, lighting, sockets, flooring, plastering, decorating and bespoke joinery should be allowed for from the outset so that quotes can be compared on a like-for-like basis.
Existing conservatory removal
If the project involves replacing or upgrading an old conservatory, allow for surveys, careful demolition, disposal and any work needed to make existing foundations or openings suitable.
What Should Be Included in the Quote?
- Site survey, design assumptions and measured dimensions
- Foundations, drainage and structural work
- Frames, glazing, doors and roof construction
- Insulation, ventilation and weatherproofing
- Heating and electrical work
- Plastering, flooring, decorating and final finishes
- Scaffolding, access equipment and waste removal
- VAT, provisional sums and a clear list of exclusions
Ask for an itemised quotation and confirm who is responsible for drawings, engineering, planning checks and Building Regulations compliance. Our broader house extension cost guide explains the main budgeting considerations in more detail.
Conservatory vs Sunroom vs Orangery
These terms are sometimes used for similar projects, but the construction is not always the same:
- Conservatory: typically has a higher proportion of glazed walls and roof.
- Sunroom: usually uses more solid, insulated construction while still maximising natural light.
- Orangery: often combines masonry walls or piers with large glazed areas and a roof lantern.
Cost depends more on the final specification than the label. If year-round comfort is the priority, compare insulation, glazing, ventilation and heating as well as appearance. See our sunroom extension service and house extension service for related options.
Can an Old Conservatory Be Upgraded?
In some cases, an existing conservatory can be improved by replacing the roof or glazing, upgrading heating and ventilation, or improving the connection to the house. In other cases, rebuilding as a better-insulated sunroom or orangery-style extension offers a more reliable long-term result.
A site survey should check the foundations, drainage, structural openings, damp protection and the condition of the existing frame before an upgrade route is recommended.
Do You Need Planning Permission?
A small rear extension, including a conservatory, may qualify as exempted development when it meets the current conditions. The assessment can depend on the combined floor area of previous extensions, remaining private open space, height, boundaries, the property type and whether the building is protected or within an architectural conservation area.
Building Regulations still apply even when planning permission is not required. Check the current requirements with your local authority before work begins. You can also read our planning permission guide and the South Dublin County Council House Extension Design Guide 2026.
How to Set a Realistic Budget
- Decide how the room will be used and whether it must perform comfortably all year.
- Choose an approximate size, roof type, glazing level and finish.
- Arrange a site survey to identify access, drainage and structural constraints.
- Confirm the planning route and any professional input required.
- Compare itemised quotations with the same inclusions and specifications.
- Agree an appropriate contingency with your designer, builder or quantity surveyor.
Why Choose OS Holding?
OS Holding provides a complete design and build service for home extensions, including site surveys, planning guidance, construction and project management. Our team can help you compare a glazed conservatory-style design with a more insulated sunroom or orangery approach so that the finished space suits your home, budget and intended use.
Contact OS Holding to arrange a free site survey and discuss an accurate quotation for your project.
Costs and guidance checked in August 2026. Prices and planning requirements can change, so confirm the latest position before making a final decision.
Conservatory Extension Cost FAQs
How much does a conservatory extension cost in Ireland?
For early budgeting, OS Holding’s current extension guidance indicates approximately €2,200 to €2,500 per m² for a basic finish and €3,500 to €5,000 per m² for a high-spec glazed finish. The final quotation depends on the design, glazing, roof, structure, access, services and finishes.
Is a conservatory cheaper than a house extension?
Not always. A simple conservatory may cost less than a highly finished solid extension, but high-performance glazing, roof systems, structural openings and heating can narrow the difference. Compare complete specifications rather than relying on the project name.
Do I need planning permission for a conservatory in Ireland?
A small rear conservatory may be exempted development if it meets all current conditions. Previous extensions, remaining garden space, height, boundaries and the status of the property can affect the assessment. Confirm the position with your local authority before work starts.
What is the difference between a conservatory, sunroom and orangery?
A conservatory normally uses more glazing, a sunroom generally has more solid insulated construction, and an orangery often combines masonry elements with large windows and a roof lantern. The exact design and specification matter more than the label.
Can an old conservatory be converted into a year-round room?
Sometimes. Options may include improved glazing, an insulated roof, better heating and ventilation, or rebuilding as a sunroom or orangery-style extension. A survey is needed to assess the foundations, frame, drainage and connection to the house.
How do I get an accurate conservatory extension quote?
Start with a site survey and a clear brief covering size, glazing, roof, heating and finishes. Ask for an itemised quotation that states VAT, professional fees, provisional sums and exclusions so that different quotes can be compared fairly.
Planning a Conservatory-Style Extension?
Book a free site survey with OS Holding. We will review the property, discuss conservatory, sunroom and orangery-style options, and prepare a quotation based on the design and specification that suit your home.
