Exterior Perimeter and storing items up against outside of facility

I can not find a written rule about how much space must be maintained along outside perimeter of facility.       I know it has to be a certain number of feet or inches not to be considered a potential for pest harborage.  Can anyone help with the specifics of the rule... what does SQF or FDA say?

Not familiar with SQF nor FDA having a Specific clearance requirement on this. Do see in my travels 2.5-3 foot clear space from exterior perimeter wall normally flat and filled in with gravel and of course flush kill boxes for rodents place 25, 50, 75 feet apart based on PCO recommendations, etc.

my concern is storing pallets up against the building.    

"11.2.12.1 The methods and responsibility for pest prevention shall be documented and effectively implemented. The premises, its surrounding areas, storage facilities, machinery and equipment shall be kept free of waste or accumulated debris so as not to attract pests and vermin"

That being said, harborage could be considered a longer term issue. If you store pallets for 2 or 3 days before they are eliminated / moved out, I don't see that as an accumulation of debris, but a temporary holding area. I would still recommend they not be stored against the building but 12" - 18" away if possible. We set our used plastic totes next to the building and it has never been cited as we have explained that they are removed weekly.