Your own building in Berlin: assessing a green roof – guide

Editorial team·updated on 15 Sep 2026

Deadlines, funding rates, responsible offices, projects and events in this guide come live from our records. They are not written into the text and are not maintained twice.

Your building in Berlin has a flat roof: bitumen, gravel, a few vents. In summer the heat stands under the top-floor flats, and in heavy rain everything runs into the combined sewer. A green roof answers both. Before you commission anyone, three questions need settling – in this order: will the roof carry it? Are you allowed? And is your address inside the funding area?

Your starting point

You decide about the roof, but rarely on your own. As a sole owner you need not ask anyone. In a Wohnungseigentümergemeinschaft (condominium owners' association) a green roof is a structural alteration under the Wohnungseigentumsgesetz (condominium act): it has to be resolved or permitted, and how the costs are shared depends on the majority by which the resolution passes. As a tenant you cannot build a green roof – you can propose one, and you are entitled to know that its cost may not be passed on to your rent.

On the roof itself four figures count: the area (in Berlin eligibility for funding only starts at 100 square metres of vegetated area), the pitch (extensive greening is typically a flat-roof matter), the condition of the waterproofing and the available load reserve. And a fifth: age. Only existing buildings are funded, and only from three years after occupancy.

Is this realistic?

Extensive greening – sedum, wild perennials, eight to fifteen centimetres of substrate – weighs in the order of 80 to 170 kilograms per square metre when saturated. Whether your roof takes that is not answered by a catalogue but by a structural engineer. Berlin's older buildings often have no original structural calculation; then the first step is a structural survey. Professional planning is not advisable here but required: responsibility for stability, fire safety and fall protection stays with the client, even when a funding programme pays a share.

The second hard point is the waterproofing. A green roof only goes onto intact, root-resistant waterproofing – the technical benchmark is the green roof guideline of the Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau. If a roof renovation is due anyway in the next few years, that is the moment; nobody builds a green roof onto waterproofing that will be replaced in five. Roof coverings containing asbestos or PVC are excluded.

What is not realistic is getting a usable roof garden as a by-product. As soon as the roof is to be walked on and used, the use changes, railings, access and much higher loads come with it – that is a different building project. The best way to see what green roofs look like in Berlin is at existing projects:

Step by step

1. Check area and address Measure the roof and deduct accesses, roof lights, ventilation openings and building services – what remains is the eligible area. Below 100 square metres of vegetated area there is no state funding. And: GründachPLUS applies only inside a binding funding area defined by a list of postcodes in the annex to the guideline. If your address is not on it, the funding falls away – the project does not.
2. Have the structure assessed Commission a structural engineer to check the load reserve. Stopping point: if the assessment shows the additional load cannot be carried, the route to an extensive green roof ends here – or turns into a strengthening project with a cost dimension of its own.
3. Collect consents and permits Pass the resolution in the owners' association. If the building is a listed monument or lies in a monument area, you need permission from the lower monument protection authority in your Bezirk (district). Whether a building permit is needed as well is settled by the district building control office. Stopping point: all official decisions must be in place by the time the funding is approved, and you have to declare that expressly.
4. Commission the planning Build-up, substrate depth, plant selection, drainage, fall protection and – if wanted – combination with a solar installation belong in a proper plan. Planning costs are eligible: 75 per cent, up to 15,000 euros; doing roof and façade together raises it to 85 per cent and up to 34,000 euros.
5. Apply for funding before you commission anything The application goes on the prescribed forms to IBB Business Team. Required documents include proof of ownership, site plan, area calculation, quotes from specialist firms, photos, a financing plan and a declaration that work has not begun. Stopping point and the most common mistake: concluding a supply or works contract already counts as starting. Sign only after the grant decision – otherwise the funding is gone.
6. Obtain three quotes and award the contract For direct awards, at least three firms must be invited to quote; invitation, quotes, selection and outcome must be documented. The work must be carried out by suitably qualified people.
7. Build, complete the establishment care, file the proof Establishment care is a binding part of the funded project and its cost must be evidenced by a quote from a specialist firm. After acceptance of the work you apply for payment; the proof of use, with a report and photos, is due at the latest three months after completion.
8. Deregister the area with the water utility Nobody does this for you: reporting the green roof to the Berliner Wasserbetriebe, which can reduce the rainwater charge, is expressly the applicant's own task. This is the part that saves money permanently.

Time and cost

Time: from the first structural question to the decision, several weeks to months are realistic; the installation itself takes days. Approved measures must begin within one year of the decision becoming final – the deadline is generous, coordination in an owners' association is not.

Cost: as an order of magnitude for extensive greening installed complete, roughly 25 to 80 euros per square metre, depending on build-up and roof condition – an editorial market range, not a quotation. Not included: structural assessment, planning, scaffolding, any new waterproofing needed, fall protection.

Upkeep and follow-up costs: extensive means low-maintenance, not maintenance-free – after the mandatory establishment care, one or two inspections a year remain for outlets, self-seeded woody plants and safety strips. Ten years of retention obligation mean ten years of upkeep. Against that: heat protection, a longer life for the waterproofing, and the possible reduction of the rainwater charge, which the water utility bills at 1.809 euros per square metre of drained area per year according to its tariff page.

What are you allowed to do?

Building law. Simply greening an existing flat roof is usually not a project requiring a building permit. It becomes one if the use changes – for instance because the roof turns into a walkable terrace – if the load-bearing structure is altered, or if railings and fall protection then become necessary. That is an assessment, not an official answer: whether your project is permit-free is decided by your district's building control office. Conversely, the Bauordnung für Berlin (Berlin building code) can require greening on certain roofs – then it is an obligation and for that reason expressly not eligible for funding.

Monument protection. For a listed monument, or in its immediate surroundings, altering the appearance requires permission under the Denkmalschutzgesetz Berlin; the lower monument protection authority in the Bezirk is responsible. A flat roof is often not visible from the street – the question still has to be asked rather than answered by you.

Consent and responsibility. In an owners' association a resolution is needed, regardless of who pays. And feasibility, adequate structural capacity, fire safety and fall protection are the client's responsibility – the funding guideline says so explicitly. Who is responsible in your Bezirk and where you can ask free of charge beforehand:

Matching funding

GründachPLUS is the state programme for roof and façade greening, administered by IBB Business Team. Four conditions decide your project, whatever the rate: the funding area (a binding list of postcodes in the annex to the guideline), existing buildings more than three years after occupancy, at least 100 square metres of vegetated area, and a vegetation-bearing layer of at least eight centimetres, ten on average. The grant itself is banded by substrate depth and reaches well into three figures per square metre at the top, with surcharges for a biodiversity green roof and for fall protection needed for maintenance – the current rates, deadlines and sources are in the dataset below and not in this text, so that they do not go stale when the guideline changes.

Three exclusions are easily overlooked: new buildings are not funded, nor is the renovation of an existing green roof, nor anything that is required anyway – by a development plan, a condition in a building permit or the Bauordnung für Berlin. In return there is clear tenant protection: neither the grant nor the owner's own share may be passed on to the rent or used to justify rent increases.

The work belongs in expert hands – structural capacity, root-resistant waterproofing and fall protection are not DIY subjects:

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