A tree house designed for a Primary School has now had to be erected outside of the school's own grounds to address concerns about risks to children created by the structure being within the school premises. This decision had been made by the Local Authority who employ the staff at the school.
There are no health and safety regulations that specifically apply to tree houses. There are industry standards for playground equipment but these are not mandatory.
The tree house is in use in another location so it is very likely that any safety concerns could have been dealt with and the tree house used in its original planned location. This seems to be a case of risk averse behaviour possibly on grounds of potential civil liability.