In Poland it's 35 square meters of footprint of a single storey building as long as the land is designated as buildable or recreational. But it has to conform t

In Poland it's 35 square meters of footprint of a single storey building as long as the land is designated as buildable or recreational. But it has to conform to a plethora of local zoning laws making it kind of tricky. Once you fall out of notification only proces it can take a long time to receive a permit.