Common bodge from the past when the windows were one integrated unit. Install from the inside, seal on the inside, non-sealed outside so water gets in between the window and the brickwork.
As I understand it, window tech has moved on a bit and the panes are installed after the trim has been fitted allowing the installer to do the correct sealing on both inside and outside without the need for a ladder or scaffold.
Common bodge from the past when the windows were one integrated unit. Install from the inside, seal on the inside, non-sealed outside so water gets in between the window and the brickwork.
As I understand it, window tech has moved on a bit and the panes are installed after the trim has been fitted allowing the installer to do the correct sealing on both inside and outside without the need for a ladder or scaffold.