Doors, windows, poly-seal

At this stage the doors will be installed. In some cases the contractor will only install the construction doors which are temporary doors so the original doors do not get damaged.

Window could have been installed at anytime after the framing stage, but now is as good as time as any.

Before the insulation your contractor will poly-seal the whole house. The is a yellow foam the seals holes and cracks (windows, door jams, exterior wall plugs, etc.) so that the home does not have any drafts or air escapes.