Adding & Extending 2026

Adding a conservatory and balcony: costs and planning at a glance

More light, more space, more living value: a conservatory or a subsequent balcony lifts your home to a new level. We give you the 2026 costs for cold and warm conservatories, for free-standing balconies and timber structures – and what matters when it comes to approval.

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Adding a conservatory: cold or heated?

A conservatory connects living space and garden and creates a bright retreat. The use and cost are decided above all by the question: cold or warm conservatory? The cold conservatory remains unheated and mainly serves as weather protection and a transition space – pleasant in summer, cool in winter. It is noticeably more affordable and generally easier to get approved. The warm conservatory is heated, insulated and usable all year round as full living space. Because it has to meet the requirements of the Building Energy Act, the costs for glazing, insulation and heating technology rise noticeably.

The legal basis for the energy standard is the Building Energy Act (Gebäudeenergiegesetz, GEG). For a heated conservatory, good triple glazing, effective shading and well-thought-out ventilation are a must, so that the room does not overheat in summer and does not cool down in winter.

Conservatory type	Reference size	Costs 2026	Note
Cold conservatory (unheated)	approx. 15 m²	€8,000 – €25,000	Weather protection, not usable year-round
Warm conservatory (heated)	approx. 15 m²	€30,000 – €60,000	Usable all year, GEG insulation standard required
Living conservatory with foundation	approx. 20 m²	€40,000 – €80,000	Full living space, with structural design & heating

Guide values for 2026, without guarantee. The actual costs depend on size, material, foundation and local tradesperson rates.

Adding a balcony afterwards

In the vast majority of cases, a balcony can be added later, too – the decisive factor is the right construction. The simplest is a free-standing balcony: it rests on its own posts in front of the facade and barely loads the exterior wall, which makes it the most sought-after solution for retrofitting. The attached balcony is anchored directly to the facade and needs a load-bearing wall as well as structural proof. A projecting timber structure or a roofed loggia creates a particularly homely sitting area.

Before the addition, you should have the structural stability of the existing building, the sealing of the transition and – for semi-detached or terraced houses – the boundary distances to the neighbour checked. A timber structure impresses with warmth and looks, but requires regular care against the weather.

Balcony type	Reference size	Costs 2026	Note
Free-standing balcony (on posts)	approx. 6 m²	€5,000 – €12,000	Own posts, independent of the facade
Attached balcony (fixed to the facade)	approx. 6 m²	€6,000 – €15,000	Additional wall anchoring, structural proof required
Projecting timber structure / loggia	approx. 8 m²	€8,000 – €20,000	Timber construction, roofed on request

Guide values for 2026, without guarantee. The decisive factors are material, size, structural design and the condition of the existing wall.

Approval: the points you should clarify

Both the conservatory and the subsequent balcony change the volume of the building and are therefore almost always subject to approval. The specific rules – for example on setback areas, boundary distances and the permissible footprint – are laid down by the state building codes, whose common framework is formed by the Model Building Code (Musterbauordnung) of the Conference of Building Ministers. Therefore, clarify the approval question with your local building authority before awarding the contract.

For semi-detached and terraced houses, neighbour law also takes on great importance: if the boundary distance is affected or the shared wall is touched, early coordination with the neighbours is advisable. Our guide to neighbour law when building a house brings together the most important points. If you are considering a more extensive extension, you'll find further options in our overview of extensions to an existing house.

From €8,000

Cold conservatory as weather protection and transition zone.

€30,000 – €60,000

Heated warm conservatory, usable as living space all year round.

From €5,000

Free-standing balcony on its own posts – ideal for retrofitting.

Approval

Usually required – clarify distances and neighbour law in good time.

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Frequently asked questions about conservatories and balconies

Answers on costs, construction method and approval of conservatories, balconies and timber structures – briefly explained and up to date for 2026.

What costs should you expect for a conservatory in 2026?

The amount depends above all on the intended use. A cold conservatory (unheated, as weather protection) ranges around €8,000 to €25,000 for roughly 15 m² in 2026. A heated warm conservatory, usable year-round and meeting the insulation requirements of the Building Energy Act, usually lies between €30,000 and €60,000. A full living conservatory with its own foundation, structural design and heating can cost €40,000 to €80,000.

What is the difference between a cold and a warm conservatory?

A cold conservatory remains unheated and serves as a sheltered transition space – in winter it cools down, in summer it heats up. It is noticeably more affordable and generally easier to get approved. A warm conservatory, by contrast, is heated, insulated and usable year-round as living space. It must comply with the energy requirements of the Building Energy Act (GEG), which makes glazing, insulation and heating more expensive.

What does it cost to add a balcony afterwards?

For an added balcony of around 6 m², you should budget €5,000 to €15,000 in 2026 depending on the design. A free-standing balcony rests on its own posts and is the simplest structurally – from around €5,000. An attached balcony fixed to the facade needs wall anchoring plus structural proof and usually costs €6,000 to €15,000. A roofed timber structure or a loggia tends to sit at the upper end.

Which types of balcony are suitable for a subsequent addition?

The most common is the free-standing balcony: it rests on its own posts in front of the facade and barely loads the wall – ideal for retrofitting. The attached balcony is anchored directly to the exterior wall and requires a load-bearing substrate as well as structural proof. Cantilever balconies without posts are usually too complex for existing buildings. For a cosy, roofed sitting area, a timber structure is a good option.

Is a building permit required for a conservatory or balcony?

Usually yes. A conservatory creates additional enclosed space and requires a permit almost everywhere; the details are governed by the respective state building code. A subsequent balcony also changes the exterior outline of the building and generally requires a permit. Clarify boundary distances, setback areas and – for terraced or semi-detached houses – neighbour law with the building authority and your neighbours in good time.

Does a conservatory or balcony increase the property value?

Yes, high-quality additions generally increase living comfort and resale value. A heated living conservatory increases the countable living area, and a balcony makes flats and houses more appealing. The decisive factors are clean workmanship, energy-efficient glazing and proper approval. An unheated cold conservatory, on the other hand, usually does not count as full living area.

Can I add a conservatory or balcony myself?

Kit conservatories and simple free-standing balconies are available as systems that experienced DIY builders can partly assemble themselves. The foundation, structural design, wall anchoring and proper sealing, however, should be left to specialist companies or at least checked by them – tightness, safety and eligibility for approval depend on it. Doing the work yourself does lower the costs, but shifts responsibility and warranty risk onto you.

As of 2026, without guarantee. The costs depend on size, material, structural design and regional tradesperson rates. Whether a permit is required is determined by the respective state building code.Prefabricated House is an independent comparison portal and not a legal or construction advisory service.