There are some agreed and known challenges with capturing and publishing data for Building Age, Construction Material, Basement Presence, and Number of Floors:
There is no single, definitive measurement or information available for any of these attributes at a national scale.
There are limited and sometimes conflicting sources of information from which to derive values.
The real world can be very difficult to represent in data. For example, new builds can be made to look like older buildings.
The level of estimated conformance is perfect for 1 to 2 floors 95% of the time, but it reduces with the increasing number of stories. 95% of all buildings that have 5 or more floors will have the correct number of floors value (within 1 floor) recorded when compared with the real world.
It is difficult to accurately predict floor numbers for complex buildings with towers, spires, roof furniture, overhanging vegetation, etc.