As planned, we continued to develop our business in the Value-add Business segment. The increase in the output of our craftsmen’s organization significantly contributed to this trend and allowed us to once again continue our investments in improving our portfolio. In addition, we also continued to expand our business activities in the areas of condominium administration, the provision of cable television to our tenants, metering services and insurance and residential environment services in the 2018 reporting period. As a leading real estate service provider, Vonovia Immobilien Treuhand now provides services to a total of around 106,000 units, 82,605 of which are apartments managed by third parties.
External revenue from our Value-add Business activities with our end customers in the first half of 2018 rose by 10.2% as against the same period of 2017, from € 80.1 million to € 88.3 million. Intragroup revenue rose by 29.3%, from € 403.7 million to € 522.1 million in the same period. Overall, this results in a 26.2% increase in the revenue from the Value-add Business from € 483.8 million in the 2017 reporting period to € 610.4 million in the first half of 2018. The adjusted EBITDA Value-add Business was up 13.4% year-on-year to € 51.7 million in the first half of 2018.
The EBITDA margin of the core business, calculated based on the adjusted EBITDA Operations in relation to rental income within the Group, once again showed positive development in the current reporting period. For Vonovia, it increased to 75.3% in the first half of 2018 from 72.7% in the same period of 2017.