Plan with confidence
Secondary glazing versus double glazing for an older home
Compare a separate internal glazing layer with replacing the existing window unit, including heritage and room-use considerations.
Secondary glazing adds a separate internal pane; double glazing usually describes two panes within a sealed unit. They are different interventions with different effects on the original frame, access and appearance.
How the two approaches differ
Secondary glazing is fitted inside the existing window and can leave original frames in place. Double glazing typically uses a sealed unit in a replacement or compatible existing frame.
Do not assume that every historic frame can accept a sealed double-glazed unit. Glass thickness, frame sections, condition and historic interest can limit options.
Compare practical considerations
Consider cleaning access, operation of both layers, ventilation, condensation risk in the cavity and how the room is used. Ask how the proposal will preserve ventilation.
Energy and noise outcomes depend on the complete design, gaps, glass and fitting. Request data for the actual system rather than assuming one approach always performs better.
Check heritage requirements and availability
For a listed building or conservation area, speak to the planning authority and review Historic Environment Scotland advice before altering windows. Repair or draught proofing may be options too.
The group’s currently advertised window range does not confirm a secondary-glazing installation service. Ask what can actually be supplied and fitted before planning a quote.
Explore your next step
General planning information updated 29 September 2026. Product specifications and the work for your home are confirmed in your quotation.