Kitchen + Bathroom Extraction/Ventilation through roof

[Soulfish]

Currently refurbishing a Bungalow and need to provide extract/ventilation to a couple of bathrooms and the kitchen. For all three its currently looking a lot easier to go straight up into the cold loft space and through the roof into a universal roof vent or similar. 

 

Because of the locations of all 3 we could just about get a <3m run from the extract terminal to a soffit location, but it would involve quite a few bends and a run that is just about 3m in length. Going straight up from all 3 locations involves no bends and is a lot shorter. 

Has anyone used or got a view on the Universal Roof Vents by Vent-Axia (https://www.vent-axia.com/range/universal-roof-vents) or Klober (https://klober.co.uk/product/pitched-roofing/pitched-roof-vents/universal-20k-tile-vent)? Ideally we'd be terminating 150mm rigid insulated ducting into the roof vents. I'm assuming a condensate trap to pick up any condensation that does form is needed - but my only worry is the kitchen extract, is it fesable to do something like this or am I mad for even considering it?

[Mr Punter]

Would you look at a MVHR unit so you recover heat from extracted air in the winter?

 

Kitchen extract I prefer straight through the wall if possible but you could go up through the roof.

 

For the bathrooms you could have inline fans mounted in the loft as they cut down on noise and can provide better flow.  With the centrifugal and mixed flow ones you can have long runs and lots of bends.

 

With standard extractors and short runs of insulated ducting I don't see the point in condensate traps.

 

Just use flexible insulated ducting and connect it with jubilee clips.