Should interior window sills be installed before or after the interior plaster?

We would like to have interior window sills made of natural stone installed. Normally, the window sills are measured after the windows are installed and then mounted before the interior plastering is done.

Unfortunately, the window sills have a very long delivery time, but the date for the interior plastering cannot be postponed.

I am reluctant to measure the window sills before the windows are in because I think too much could go wrong.

What is the difference if I install the window sills only after the interior is already plastered? Is that possible? I have read that it then looks different aesthetically; can someone explain this to me?

I am reluctant to measure the window sills before the windows are installed because I think that too many things can go wrong.

Uh, yes, for example, this thread comes to mind:
Try surfing a bit with the search function; questions about window sills and interior plastering are not uncommon topics here.

Uh, yes, I have to think of this thread, for example:
Surf around a bit with the search function, the questions about window sills and interior plaster are not a rare topic here.

Thank you for your reply, I have now read through the entire thread. But unfortunately it does not answer my question, so I am trying to formulate it better...

Our construction manager prefers that the window sills be installed before the interior plastering. This would look nicer. But it also leads to the scheduling problems mentioned above because the window sills have such long delivery times.

My question now is, if you plaster first and then install the window sills, what will look visually different about the window sills?

I was told that when the windowsill is installed after the interior plaster, some plaster has to be chiseled away again on the left and right... Ok, I understand that because otherwise the windowsill won't fit, and that also means the plasterer must come back for finishing work after the windowsills are installed...?!

But it doesn't look any different at all plastered in on the left and right than if I install them before plastering, right?

My question was, if you plaster first and then install the window sills, what will look different on the window sills visually?

A picture detail from our future kitchen may help illustrate the difference. On the right window, the window sill was properly plastered, including in the window recess. On the left window, the window sill is missing because later the countertop will extend up to the window there. If you wanted to install a window sill there afterwards, the plaster in the lower part of the window recess would have to be removed again so it can be fitted on the side and then plastered again. Alternatively, a section of plaster is left out when plastering. Both options involve time-consuming rework. Hence the rule: always install window sills before plastering.

Best regards

Axel

A picture detail from our future kitchen might clarify the difference. On the right window, the windowsill was properly plastered, including in the window recess. On the left window, the windowsill is missing because later the countertop will extend to the window. If you wanted to install a windowsill there afterwards, the plaster in the lower part of the window recess would have to be removed again so that it can be adjusted on the side and then replastered. Alternatively, a piece of plaster is left out during plastering. Both mean time-consuming rework. Hence the rule: windowsills always before plastering.

Many greetings

Axel

Thanks, Axel, that’s exactly what I was looking for...

So it’s simply too time-consuming to redo it afterwards, and that’s why you install it beforehand...

Unfortunately, I have to wait 3-4 weeks for the windowsills. If I only measure after the windows are installed + 4 weeks and then the plasterer can come, my project will be delayed both by this time and additionally by a waiting period because the plasterer won’t be able to come exactly the week I need him… I’m currently looking for a solution for this...

Measuring windowsills before the windows are installed is nonsense, right?