Help foundry

I've just cleared the first room in the foundry (after iron throne quest) but we caught the attention of a watcher on the roof. So I'm stuck in combat but all the non player allies are gravitating to it's icon but on a different floor 🤦🏼 I can't figure out how to get up there. I can see an open skylight/ hatch but can't get up there.

Does anyone know how I can get up there?