There seems to be a bug.
In the image below we see a cottage as Zone 5 and an office tower as Zone 1.
zoneBug.png [ 38.83 KiB | Viewed 502 times ]
The cottage properly builds in the outer most zone and the office tower properly builds in the inner most zone.
The bug is with the zone numbers.
Town zones are concentric rings around the centre of each town. A town can have up to five town zones where zone 0 is the outer most zone and the zone with the highest number the inner most.
Town zone where the building is situated. The value is between 0 and 4, where 0 is the outermost zone of the town. Smaller towns have fewer zones. Roads are plain in zone 0 and 1, paved in zone 2, have trees in zone 3 and streetlights in zone 4
Where you describe Town Zones as 1 2 3 4 5, shouldn't that be 4 3 2 1 0?
I noticed this while working in JGR Patch Pack v27.1