Secondary glazing

Secondary glazing: design and installation choices

Add a separate internal glazed system while retaining the original window, with access, ventilation, noise and heritage needs recorded.

Secondary glazing adds an independent inner window instead of replacing the original glass with a sealed unit. It can address draughts, noise and comfort where the existing window is retained.

The gap, perimeter seals and original window condition affect the result. An airtight inner frame still needs a coordinated ventilation and condensation plan for the room.

Measurement reference

Enter the reference opening width and height. Identify face or reveal fixing and give available depth, obstructions and bay angles in the notes.

Budget and optional extras

A large acoustic or shaped window may cost substantially more. The reference does not include an agreed survey or installation scope.

Published prices on the main page state their reference size, supply or fitting scope, VAT basis and source. Add-ons are individually requested in the configurator and need separate supplier pricing.

Secondary glazing for your project

Common enquiry briefs include period sash window, road-facing bedroom, listed / heritage property, existing window upgrade. Describe the intended use and the supporting construction so the supplier can assess the complete specification. Different applications can need different glass processing, fixings and installation details.

A separate frame, not a sealed-unit swap

Secondary glazing sits on the room side of the existing window. Check reveal space and the existing handles, shutters and curtains.

Match how you use the window

A lift-out panel, sash slider and hinged casement provide different access. Choose the operation before measuring for manufacture.

What to include in a made-to-measure quote

Compare quotes using the same dimensions, quantities, finish, glass construction and installation scope. If you have a drawing or an existing specification, include its reference and identify which details still need advice.

• Secondary-window operation: Retain practical access for opening, cleaning and escape where required.
• Main objective: Ask for performance for the complete installed arrangement.
• Fixing reference: Reveal depth, handles and shutters affect the fit.
• Glass request: The original window and secondary pane work as one arrangement.
• Frame finish: Request a sample where matching existing joinery matters.
• Timber subframe / trims: Agree finishes and reveal preparation.
• Locks / restrictors: Confirm safe opening and escape requirements.
• Bay / shaped window detailing: Each facet and corner needs a measured drawing.
• Survey and installation: Include condensation, ventilation and existing-window condition.
• What should the quote include?: Ask suppliers to itemise delivery, measurement and fitting separately.

Cut-to-size dimensions, edges and fabrication

Measure the finished glass only when the fitting allowances and support details are known. Otherwise identify the opening or existing panel you measured and request a survey. Give each different size its own basket line, with its quantity and drawing reference.

Holes, cut-outs, shaped edges and interfaces with hardware should be settled before manufacture. The finished glass construction and any coatings must suit the intended environment. A screen preview or concept photograph cannot replace a sample, survey or product-specific installation drawing.

Supplier checks before manufacture

• Retain appropriate ventilation, cleaning and escape access; no acoustic or thermal value is inferred here.
• For heritage properties, obtain project-specific advice about consent and protected details before work.
• The supplier must agree the final sizes, construction and compatible fittings before manufacture.
• Confirm survey, packaging, delivery, access and installation responsibilities in the written quote.

Requesting comparable glass quotes

Save the choices you know and ask for help with the rest. The quote basket records a specification request rather than placing a manufacturing order. A firm quote needs an agreed final build, dimensions, delivery arrangements and any installation or design work.

When comparing proposals, check that glass-only supply and supply with fitting cover the same scope. Ask who provides measurement, drawings, supports, compatible hardware, lifting access and finishing work. Keep the final approved specification with the order.