A sinking fund is not a legal necessity, but it makes sense to spread the cost of future large bills relatively painlessly for the residents. It can mean, of course, that a resident pays into the fund over the time they are there and the money is not needed during that time - in which case it should enhance the value of the property on sale.
The principle is also used by local authorities, who, unlike most organisations (companies, for example) have no requirement to charge Depreciation on their fixed assets (buildings, machinery etc) and therefore don't, with the result that when an asset needs major repair or replacement there is no money to pay for it. This happened two years ago with our local Town Council who own the Town Hall. The central heating system failed (it was a thousand years old) and as yet they haven't found the money to replace it, so users of the hall (of which there are many, on a regular basis) sit in their coats and scarves with a couple of electric heaters that barely take the chill off. Of course in the "good old days" the council simply applied to central government for the money - and got it! Surprise, surprise, that doesn't happen any more.
Of course, the amount in the sinking fund may still fall short of the actual cost of the roof replacement but at least it would help.
Hysteroscopy using spinal block/epidural

