I assumed it was steel frame and should've checked. I've hunted about a bit since but all I can find is that the cladding is aluminium - like Grenfell IIRC - but can't find anything concrete (I'll get me coat) on what the main part of the building was constructed with. I have to say that from various photos it does have a certain concretey kind of vibe about it but isn't 600 feet a bit on the high side for that type of construction these days?