We have the maçons in who are about to repair the end wall of the house - lime rendering on top - so we ned to make the hole for the hotte before they make the outside all nice.
The question is - I know those expanded aluminium tubes are normally used for hottes but are they ok to go through a wall or do we need something more rigid. The wall is over 500mm thick and made of cob.
Personally I would sleeve the hole with something stronger then have your aluminium pipe go through that, it allows for easy replacement in the future as well as being stronger to begin with.
I agree with @Corona , you could use 110 mm plastic waste pipe but obviously depends on the size of the hole
For what I understand it’s 150mm but it’s my partner who is doing it and he seems to have got his mind in a knot 
You can get bigger plastic waste pipe, just need to make sure you can get the appropriate sized vent for the outside wall.
Rather than knocking a hole through ask your maçon if they can faire un carrotage (core drill) then sleeve.
Or they can be hired, but only up to 110 mm if using a hand held drill. Anything bigger needs a fixed rig (according to the hire shop - BLS, I used to use) which wouldnt be easy at the height of an extraction hood. Messy too, as you need a water hose to keep the core lubricated.
Drill a pilot hole from the inside of the house then core drill from the outside
With stone walls always use a fixing rig unless you want to damage your wrists
Thanks so much for the suggestions. I’ve passed them on to my partner who has talked with the maçon. I can hear drilling noises so something is happening although I’m not sure I dare look 
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The wall at that height is actually cob @wozza, which is both easier and harder from a drilling point of view…
I think @AngelaR said the wall was made of cob.
Edit: I see @AngelaR has already made the point. Didn’t see it on first read 
Looks like my partner is going with the suggestion that we put the flexible tube through a plastic pipe. He’s talked to the maçons and they’ve OK’d the location and also the gaines which are also going through the wall to give external light and power. All systems go here but at least the job is getting done!