We're having a precast concrete hollow core floor as our first floor. The Architect has designed it so that there is a ceiling void and as I see it this is 'only' to allow the routing of services and drainage: mains cables - to whole house, but I guess these could be routed up to the first floor ceiling and then down from there hot and cold water - pretty localised at one end of the house in the first floor. There is one bathroom at the far end of the house, but I guess pipes coul