Most of the loose ones I have come across fit that description. Though mostly on single house and barn conversion homes.Barratts and Taylor Wimpeys ? do you come across those big rectangular ones on wimpey houses which have like a black honeycomb set in them also what is the crack with pvc windows with metal sills
Wouldn't you think designers, manufacturers and builders would be getting the hang of it at this stage? Can't be that hard to design window vents to be fit for purpose, surely?