Sealant to windows

is it sealant or corking... The windows should be silicone sealed on the outside and maybe corked on the inside just for decorative effect.

Good morning, silicone and caulking is quite common when talking about sealing up on the inside of the window after the window has been trimmed, different installers have different methods when it comes to finishing a window internally and externally, the only goal that should definitely be achieved is that the window has been sealed sufficiently. Most use trims to cover the decorative edge that is left by the removal of the window, behind this trim the gap should be filled with silicone and/or foam dependant on the size of the gap, on top of the trims, the smallest silicone lines possible should be used to seal plastic to plastic and caulking should be used to seal plastic to wall. Silicone can be used from plastic to wall as it stays white for longer and is flexible so the the line wont crack, however, when decorating, paint will not take to the silicone because of its rubber form, where as caulk dries as a plaster base and can be painted on to, hope this helps, Thanks

Yes they should most definatley to prevent leaks and drafts etc

There don't need sealant on the internal only the external side

Most windows should be sealed but depends on what finished they have left. Most installers put silicone in the gap and then push a trim on it and then caulk around the trim! But most installers don’t mastic/ gap fill the trim to the window as this can discolour over time or go mouldy

Yes the internal edges of the window should be trimmed and or sealed using either a quality silicone or caulk, the cheaper silicones can tend to peel away and discolour over time. Trimming and sealing internally gives it a much neater finish I find and stops any draughts which may travel through the cavity of the wall!