The cases where we recommend it, the cases where we tell customers to spend the money elsewhere.
Triple glazing is sold as an obvious upgrade and treated as a gimmick in equal measure, and neither is right. It is a specification choice that suits some houses and some rooms very well and is a poor use of money in others.
We fit it regularly, and we also talk people out of it regularly. Here is the reasoning we use on survey.
A third pane adds another sealed cavity and another low emissivity coating, which lowers the heat loss through the glass and raises the internal surface temperature of the pane.
That second effect is the underrated one. A warmer inner pane means less radiant chill sitting next to the window and less surface for internal condensation to form on.
The strongest cases in our experience are:
Triple glazing is not automatically quieter than double. Acoustic performance comes from mass and from asymmetry, meaning panes of different thicknesses, plus a laminated acoustic interlayer.
A well specified acoustic double glazed unit will usually beat a standard triple glazed unit on a main road. If noise is your actual problem, ask for acoustic glass by name rather than assuming the third pane solves it.
Internal condensation on the glass generally reduces, because the inner pane is warmer. That is a real and noticeable benefit in bedrooms and bathrooms.
You may see occasional external condensation on a cold clear morning instead. It is not a fault. It happens precisely because so little heat is escaping through the unit to warm the outer pane, and it clears as the day warms up. It is worth knowing before it surprises you.
If the house is losing most of its heat through an uninsulated loft, solid walls or a freezing conservatory roof, the money buys more comfort spent there first. We would rather say that than sell the more expensive glass.
Weight is the other consideration. Triple units are heavier, so the frame and hardware need to be specified for it. In some slim period sightlines the frame simply is not the right home for a triple unit.
One free survey, double and triple quoted side by side, and a straight recommendation on where the money is best spent.
It is a step up rather than a doubling, and the gap varies with frame system, glass specification and window size. We quote both side by side on the same survey so you can see the real difference for your own house before deciding.
It reduces heat loss through the glazing, which is one part of the picture alongside walls, loft, floors and draughts. We will not put a figure on your bill, because anyone who does is guessing at your house.
For a sheltered, well insulated house with modest window areas, good A rated double glazing is often the sensible spend. For exposed elevations and large glazed areas it earns its place.
Yes, and it is often the smart approach. Bedrooms and the coldest elevation in triple, the rest in high performance double, all matched visually so the outside of the house looks consistent.