Now you need to install a window structure.

Now you need to install a window structure. It is better if it is a plastic window at least a double -glazed windows and at least 60 mm depth with a depth of at least 60 mm. After installing a window or balcony frame, you can proceed to the lining of the balcony with a vapor barrier film. This is necessary to protect the insulation. Then a layer of a foamed, to improve insulation. Foam, mineral wool or any other insulation. And close it from moisture with vapor barrier film. And the last stage of the lining of the balcony by a rail or drywall. Check carefully so that there are no cracks left, your comfort depends on it.