Renew windows in a house from 1967, or leave the old ones in?

Hello dear forum friends,

I have bought a house built in 1967. Now I am starting to renovate. In 1995, new windows were installed. These are double-glazed wooden windows. Should I install new ones here? The window fitter says yes. What do you think about it?

The window maker says yes.

You notice, right?

1. Frame in good condition or fixable with a new coat of paint?
if yes, then:
2. Are the seals between sashes and frame present/intact, so no drafts?
if no, then renew seals afterward, otherwise...
3. 1995 is exactly the cutoff when an infrared coating was introduced on the outside of the inner window pane. It is probably present. This lowers the U-value of the glazing from about 3.0 W/m²K to 1.5 - 1.0 W/m²K
How to find out: Lighter test glazing – hold a lighter in front of the inner window pane. In the reflection you see four! flames. The first two are from the inner pane, the others from the outer pane. The first two flames in the reflection should have different coloring, the second is slightly pinkish.

If that is the case – leave it as is. Otherwise, have the glass replaced (around €100/m² including installation), preferably with triple glazing if it fits or at least with warm edge spacer.

The window installer says yes.

Makes sense. 23 years, any layman would believe they wouldn’t pass the vehicle inspection for much longer ;-)

I fully agree with my predecessor. The suspension can be readjusted, seals can be renewed, locking pins can be upgraded, glass panes can be replaced (and two panes are not necessarily worse than three). So, if the frames are still in good condition: avoid the hassle of replacing them.

Check everything on the weather side where water can drip and run behind. The transition between window and windowsill is such a problem area where moisture often remains inside. It still looks good visually but can be pressed in with a finger like a cake. (So der aktuelle Stand in der noch von uns bewohnten Mietwohnung, einige Fenster wurden schon getauscht deswegen)