Roof Renovation Cost Efficiency

Hello, we have a 50s house. The roof has Meyer Holsen tiles, a company based in our region known for good tiles. However, these were fixed back then with some kind of mortar that is now partially starting to crumble, and a few parts sometimes fall off the roof. We had already considered renewing the entire roof (with doubling of the rafters), also from an energy efficiency/funding perspective. However, we are looking at around 45,000 EUR for that. An alternative would be to take new tiles and renew the gutters. The costs for that still need to be estimated. Now my question is, is there a possibility to renovate the partially crumbling roof or is it not worthwhile for cost reasons since you would start renovating again in 10, 20 years or so? The downpipes would have to be done anyway and at least the top floor ceiling insulated. Does anyone have experience with the costs for something like this? Many thanks in advance!

If you want to replace the bricks anyway, then just do everything completely. Especially since nothing is insulated yet. You should inquire with an energy consultant, some counties also offer free consultations.