Window sills aluminum or granite

That one should use good stuff, agreed - but, (assuming that '87 refers to your birth year) I do not share the assessment that the current one will also be your last built house. This "principle" applied when eightieth birthdays were a rarity and only the abandoned and widowed remarried a second time.

that was the last house ☝️

that was the last house

Double swear? - that's what you say now. But when it's paid off and the dog is literally buried, then a colleague your age (still with the fresh impression of the cousin’s stairlift remodeling stress) invites you to his newly built soon-to-be retirement home. Then you really have to be especially "strong-willed" to stand by that bold statement from Mother's Day 2020.

Hello dear community, I have to bother you again. The granite window sills outside... when will they be installed and who usually does this? Before or after the insulation? We are getting 18cm insulation, stone 17.5cm. The fact was that we are getting these sills and I now have to plan when they should be on site and in place.

I only know it "before" the insulation. 18 cm ETICS also means that the window sills cantilever most of their depth. There must be an appropriate fastening, which I honestly can't really imagine how it should work "afterwards". To be honest: if you had mentioned the wall structure beforehand, I would have advised against the heavy sills as well.

After insulation before plaster.

The wall structure does not matter at all, don’t be discouraged. The bench is supported by a fastening system on the ETICS, no problem at all.

It’s best to just ask the involved trades how they see it. Window sills usually come from the local stonemason who also installs them. For aluminum things, the window installer does it; you can also ask them if they have a cooperation partner.