This is typically decided by treaty and negotiation. As such, things greatly depends on who has possession of what and at what time.
Many nations choose to take possession of the property first so they can dictate the terms of construction, but things do not always work out that way. If compelled for some reason, such as time constraints, the nation may choose to inhabit an existing structure at the site which was likely constructed upon local building codes.
On the other hand, once the nation takes possession of the property it becomes sovereign territory and can be constructed to any standard level high or low and no one can oppose that unless it was part of the negotiations.
In practice, some nations do allow emergency personnel from the local authorities should their own personnel become overwhelmed, but it tends to be limited in nature and with escorts.
MKDesign 