Hi Michael,

You are so right! I made geojson's in QGIS off of January 2017 imagery. Thank you for all your advice, I am finding my way and feedback really helps. I will do my best to fix all the errors:
1. use house number tag
2. remove null values
3. clear area values

The thing is we are using MAPS.ME to support the local neighbourhood watch and community register run by residents of the informal settlement. Updating the rooftops and labelling the houses with their registration numbers was done to assist the teams on the ground with their day-to-day operations. They're also locating critical services (taps/toilets) on M.M and sharing the status with the city repair team.

We would like to organise an OSM training event for our geospatial teams but have been unable to find active, experienced users in Cape Town. Is there anyone you could recommend?

Best wishes,
Chris Berens