Retain historic detail and check permissions before committing to an installation.
Start with the building
Record the existing windows, shutters, panelling, mouldings and historic glass. A secondary frame can affect internal features even when little changes outside. A careful design works around those features rather than treating the reveal as an empty opening.
Historic Environment Scotland identifies secondary glazing as an option for improving traditional windows. Suitability still depends on the particular building and proposal.
Check with your local authority
Listed building consent and planning permission are different processes. Do not assume that an internal or removable installation is automatically exempt. Ask the local authority planning or conservation team what is needed for your proposal before ordering or starting work.
For an unlisted building in a conservation area, establish the applicable controls and whether the proposed work needs permission. Written advice based on the actual details is more useful than a general assurance from a salesperson.
Prepare useful drawings
Provide photographs, opening details, frame colour and sections showing fixing positions and depth. Show how the new glazing lines relate to the original meeting rails or glazing bars. Explain access, ventilation and how existing shutters will operate.
Describe how fixings affect the original fabric and how removal would be handled. Reversibility can be a useful design consideration, but it does not itself remove a requirement for consent.
Repair before installation
Investigate water ingress and decayed timber before fitting the inner glazing. Make sure the original windows can still be inspected and maintained.
Consult the current Scottish guidance linked on the Resources page and obtain project-specific advice. This guide is general information, not a consent determination.