Frequently asked questions 

What is heritage double glazing?

Heritage double glazing (also called slimline or conservation double glazing) uses a much thinner sealed unit — typically 11–14mm compared to the 20–28mm standard for modern windows. This narrower profile fits into original timber sash and casement frames, letting listed and period buildings gain the thermal and acoustic benefits of double glazing without altering the historic glazing bars, sightlines or overall appearance of the window. 

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What thicknesses do you manufacture?

We manufacture slimline units from 11mm to 14mm. Get in touch with your frame rebate depth and we'll confirm the right specification. 

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 What glass types and spacer options are available? 

We offer a range of glass from annealed to toughened from clear to coatings like soft coat or hardcoat, we can also offer a range of patterned glass including satin glass. We are also pleased to be able to offer traditional style glass.

 

 What thermal and acoustic performance can I expect?

Even at slimline thicknesses, heritage double-glazed units significantly outperform single glazing for both heat loss and sound insulation. Exact figures depend on the glass and spacer specification.

 

What's the maximum and minimum unit size you can manufacture? 

Our toughened sizes are minimum 120mm x 290mm.

Maximum size 4mm cavity 500mm x 1000mm or 600mm x 600mm.

Maximum size 6mm cavity 700mm x 1500mm or 800mm x 800mm. 

 

What warranty do you offer?

All of our 7mm+ sightline units come with a 3 year warranty.