Rooftop Conversions
Rooftop
Conversions
Conversions
The conversion of rooftop floors into premium residential units has been a feature of West Berlin's property market since the early 1980s. EnTerra has built a substantial track record in this discipline — identifying structurally suitable buildings, securing construction consent, executing technically demanding rooftop extensions, and delivering finished penthouses to a discerning owner-occupier market.
Our approach is selective by design. We focus exclusively on well-maintained buildings with an existing lift and a strong owner-occupier base, in locations where the planning framework and architectural character support a premium product. We do not operate in the lower quality segment, where the absence of lifts, deferred maintenance and weak WEG (Wohnungseigentümergemeinschaft — owners' association) governance make rooftop conversion economically unattractive.
Across five completed projects in Berlin — spanning Schöneberg, Steglitz, Friedrichshain and Treptow — EnTerra has delivered more than fourteen rooftop apartments, several of which were retained in the portfolio for their long-term income characteristics.
Our approach is selective by design. We focus exclusively on well-maintained buildings with an existing lift and a strong owner-occupier base, in locations where the planning framework and architectural character support a premium product. We do not operate in the lower quality segment, where the absence of lifts, deferred maintenance and weak WEG (Wohnungseigentümergemeinschaft — owners' association) governance make rooftop conversion economically unattractive.
Across five completed projects in Berlin — spanning Schöneberg, Steglitz, Friedrichshain and Treptow — EnTerra has delivered more than fourteen rooftop apartments, several of which were retained in the portfolio for their long-term income characteristics.
Quality Framework — Three Categories
Category 01
Standard — no lift
Buildings of medium quality in a secondary location, without a passenger lift. Frequently burdened by deferred maintenance and a weak WEG structure. Purchase prices have historically been below €2,000/sqm. EnTerra does not operate in this segment.
Category 02
Good quality — lift extended
Well-maintained buildings with an existing passenger lift capable of extension to rooftop level. Owner-occupier base above 75%. Roof pitch can be optimised from 45° to 60°, creating additional floor area and headroom. EnTerra's primary operating segment. Target exit price: above €6,000/sqm where listed-building criteria also apply.
Category 03
Premium — listed, double-height
Architecturally distinguished buildings where the roof structure permits two storeys, typically incorporating a gallery level. Usually a heritage-listed (Denkmal) property. Scarce supply; significant AFA depreciation advantage. Exit prices typically well above €6,000/sqm. Lift extension and bespoke rooftop terrace are standard.
Selection Criteria
For a Category 02 or Category 03 project to proceed, the following conditions must be met. The first five are prerequisites; the additional criteria below, where also satisfied, support a premium exit price.
- Location: the building sits in an established residential district with sustained rental and resale demand.
- Owner-occupier base: more than 75% of existing units are owner-occupied, ensuring a competent, engaged WEG.
- Building management: a professional Hausverwaltung is in place.
- Lift extension: the existing lift can be extended to rooftop level without structural compromise.
- Roof structure: the existing roof geometry can be optimised, delivering meaningful gains in floor area and internal headroom.
- Aspect: the building is oriented on an east–west axis, giving morning sun on one terrace and evening sun on the other.
- Side wings: staircase landings in the side wings can be designated as exclusive-use ancillary space, adding up to 50 sqm per wing to the usable area.
- Terrace structure: an elevated rooftop terrace is technically feasible and planning-approved.
- Heritage listing: façade and/or staircase are listed (Denkmalschutz), providing AFA depreciation benefit to buyers.
Track Record — Completed Projects
| Address | District | Units | Notes | Status |
|---|---|---|---|---|
| Helmstedter Str. 26 | Schöneberg | 2 | Two penthouses of approx. 220 sqm each incl. rooftop terrace and gallery level. Heritage listed. Completed 2011–12. | Sold |
| Am Treptower Park 21 / Moosdorfstr. 1 | Treptow | 4 | Four rooftop apartments. Waterside location adjacent to Treptower Park. | Held / Sold |
| Heylstr. 1 / Koburger Str. 16 | Schöneberg | 2 | Two rooftop apartments with elevated rooftop terraces. | Held / Sold |
| Muthesius Str. 23–25 | Steglitz | 2 | Two penthouses built to KfW 40 low-energy standard. Highly efficient fabric-first construction. | Held |
| Revaler Str. 9 / Libauer Str. 12 | Friedrichshain | 4 | Four rooftop apartments with elevated rooftop terraces. Corner location. | Sold |
Case Study
Completed 2012 — Sold
Helmstedter Str. 26, Berlin-Schöneberg
2 × 220 sqm
Floor area (incl. terrace)
€1,265/sqm
All-in entry cost
~€4,100/sqm
Exit price (2012)
Heritage
AFA depreciation eligible
The building at Helmstedter Str. 26 was acquired in 2011 at approximately €1,150/sqm, with acquisition costs of 10% bringing the all-in entry cost to €1,265/sqm. Construction costs, including all ancillary costs and VAT, were budgeted at €1,800/sqm, yielding a total all-in cost of under €3,000/sqm for a finished premium product. The two apartments — each approximately 220 sqm including rooftop terrace and a full gallery level — were sold in 2012 at approximately €4,100/sqm, a margin reflecting the scarcity of the product type in that location and the heritage depreciation benefit available to buyers. With the exception of the heritage listing, the project satisfied every quality criterion in EnTerra's framework.
Project Photography
During — interior shell, finishes stage
During — fitout, screed and first-fix
Lift extension — glass shaft, courtyard elevation
After — Altbau exterior with DG roof conversion
After — completed interior, floor-to-ceiling terrace doors
After — DG living space, Velux and balcony access