ᐅ Garage – roof drain is leaking

Hello,

Water is leaking into my garage (flat roof with roofing felt, or bitumen as it is probably called). The roof drain is leaking (see the patchwork job done by the previous owner).

My question:
Which tradespeople are responsible for this? Plumber? Roofer? Or someone else?

Best regards,
Volkmann

I would contact a roofer. If the issue is with the waterproofing membrane, the drainage, or the sealing, they are most likely the ones who can fix it. (Layperson’s opinion)

What is the purpose of this unusual structure below the ceiling, and who originally built the garage?

Regards, Bauexperte

Perhaps the previous owner wanted to recreate Beuys' fat corner.

I don't know who built the garage. Willi is no longer alive.