Adam: From memory (its several years since I was auditing this type of installation abroad..). There is (there wasn't) any 'industry standard' or 'official guidance' on what this actually means... In practice, following the French explosion, and in light of others over a number of years - I believe most if not all operators decided to adopt the 2m stack height as an effective maximum. If I were looking to increase the height for any reason (and it would need to be a really really really good reason) then I would be looking for: Lightweight construction - roof and walls to prevent excessive over pressure (but not Dutch Barn type roof that cannot exclude rodents and birds etc). Remote siting - remote from any occupied buildings and (perhaps more importantly) remote from any bulk storage of other potentially hazardous materials (ammonia spheres, oil tanks etc....) Very high standards of cleanliness - floors and walls that can be washed regularly (not Dutch barn type witih open sides. Robust early detection and alarm system, coupled with a drench or deluge system that might stand a chance of extinguishing any incipient fire. Emergency procedures that do not rely on firefighters needing to approach with hoses.... But these are effectively the precautions for a store with 2m stack height limit anyway....