Yep, I'm with you on the shelf and as you specified a dimension between shelves and where the lowest shelf should be, you could pull him up if they aren't that distance apart.
He may try to argue that you didn't say that and if he does, that's the point you should tell him to leave and find another carpenter.
Next chapter, having a cupboard made around the boiler in the bathroom and cupboard for washing machine and dryer.
Maybe I’m overly worrying now but this looks a bit too tight!?
Edit: apologies wasn’t meant to be a reply
Yep, I'm with you on the shelf and as you specified a dimension between shelves and where the lowest shelf should be, you could pull him up if they aren't that distance apart.
He may try to argue that you didn't say that and if he does, that's the point you should tell him to leave and find another carpenter.
Tradespeople can be notoriously dense.