Posted: Sat Dec 31, 2022 8:29pm
If this terrace/solarium is for your own private use, then it's unlikely to be covered by any communal insurance.
Are there any cracks or gaps in the grout between the tiles? including any upstands at the edges? If so then a regrout with a good quality flexible, frost resistant grout would be the way to forward. This could be a relatively easy diy job with the correct tools. You don't have to do the lot at once, in fact I've just done mine over a couple of weeks grouting a few M2 per day when I felt up to it.
If many of the tiles are cracked & loose then a re-tile could be the way forward. More expensive than a regrout and I would get someone in to do this, especially if it involves removing all the old tiles.
The membrane should still be OK, unless the roof is very old. Our is circa 2007 and the membrane consists of 4mm rubber sheet which is never subjected to sunlight.
Whatever you do, don't go for the painted sealant. A cheap temporary solution which could last year or two.
Good luck