Had this in the 11-flat block I bought into. Basically the developers span up a PLC in the name of the building, each flat owner owned one share in 11. We all paid management fees into the PLC each year and managed the company ourselves. From these fees were covered communal area cleaning, gardening, maintenance, the accountant and most importantly buildings insurance. On a leasehold this is critical as if the building is destroyed your flat's contents insurance isn't going to cover rebuilding it!
This was much cheaper than the fees you normally pay in a block and allowed us to save some aside for emergencies (e.g. access gate needed replacing at a cool £10k). However, it is a PITA when trying to get agreements on certain things basically you have to get shareholder majorities to enact changes.
Oh and before I sold up we subcontracted a maintenance company to do the heavy lifting as I ended up doing everything as I was the only owner/occupier (the rest were landlords). DON'T DO THIS, all they care about is extracting the most money for the least effort.