Secondary Glazing for Victorian Terraces

Draughts come from shrunk timber and worn parting beads. Noise comes from 4mm glass plus perimeter leakage. Cold comes from a U-value around 5.0 W/m²K on single glazing — worse than an uninsulated brick wall.

A single secondary system addresses all three: the sealed cavity stops air movement, the acoustic laminate blocks sound, and the trapped air layer drops the U-value to roughly 1.8 W/m²K.

The Victorian bay is the technically demanding part of any terrace project. Angled returns mean the secondary frames must be mitred to the bay geometry rather than fitted as three independent rectangles, or you get visible gaps at the corner joints.

We survey bays with a laser to capture the actual internal angles, which in a settled terrace are rarely the nominal 45 or 90 degrees.

Most owners start with the two front bedrooms and the front reception — the rooms where street noise costs sleep and quiet. Rear elevations and the return can follow later; because each unit is independent, there is no penalty for phasing.