Victorian Bay Sash Windows, SE London

01 · The Project

The Brief

This South East London project covered both halves of a period bay: the windows and the structure that frames them. We installed new Victorian-style timber windows and carefully reconstructed and refurbished the existing concrete bay window surrounds, then repainted them.

The aim was to preserve the property's original Victorian character while improving energy efficiency, acoustic insulation and durability.

Victorian bay sash windows are hard to treat in isolation. On a front like this one, the moulded window heads, pilasters, projecting sill and corbels carry as much of the character as the sashes do. New joinery set into worn surrounds still leaves a worn-looking bay, so the windows and the surrounds were handled as a single job.

Before

After

02 · The Structure

Reconstructing the Concrete Bay Surrounds

Projecting sills and mouldings take the worst of the weather on any elevation, which is why they are so often the first part of a bay to need attention. A window replacement can stop at the frame and leave all of that untouched. Here, the existing concrete surrounds were part of the scope, reconstructed and refurbished alongside the new windows.

The before photo shows how far this bay had gone. Paint was flaking from the old sashes and the sill, and on the right-hand side the outer pilaster was missing altogether, leaving bare brick between the head and the sill. The finished bay has a full pilaster there, so the moulded heads, square pilasters, long projecting sill and paired corbels read as one surround again. The surrounds were then repainted in a warm cream, which stands out against the dark red brickwork and frames the white sashes cleanly.

03 · The Joinery

Two Timbers for Victorian Bay Sash Windows

The windows use two different timbers, each chosen for the part it plays. The box is the fixed part of a sash window, with the sashes running inside it, while the sashes are the parts that move and carry the glass.

The boxes are Sapele, a dense hardwood with the strength to give each window a firm, durable frame. The frames and sashes are premium Accoya, timber that has been acetylated, a process that changes the structure of the wood so it no longer readily absorbs water.

Timber that takes on less moisture swells and shrinks less through the seasons, which is what usually causes sashes to stick, joints to open and paint to split. There is more on the material in our guide to Accoya windows in London.

04 · The Performance

Acoustic and Energy-Efficient Glazing

Behind the traditional appearance of these Victorian bay sash windows sits a modern double-glazed unit, specified to deal with both noise and heat loss.

Each layer does a separate job. Acoustic laminated glass has an interlayer that damps sound vibration, so less street noise reaches the room. A low-emissivity coating on the inner pane reflects radiant heat back inside, and warm-edge spacers reduce heat loss around the edge of the glass, where a unit is usually at its coldest. If noise is your main concern, our guide to acoustic glass and soundproof windows explains the options, and our double glazed sash windows page covers glazing more widely.

05 · The Detail

Paint and Finishing

The windows were finished with a professional timber coating system, chosen for long-lasting protection against the weather and a smooth, elegant appearance.

RAL 9016 is a clean, bright white, and it keeps the sashes crisp against the warmer cream of the surrounds. A stable timber also helps the coating last, because the surface underneath moves less from season to season.

06 · The Outcome

The Result

The finished Victorian bay sash windows combine traditional architectural character with modern performance: beautifully crafted timber joinery, excellent acoustic insulation, improved energy efficiency and long-lasting durability, all set within surrounds that have been reconstructed and repainted.

If you have a period bay where both the windows and the surrounds need attention, it is worth looking at them together. See our bay sash windows and sash window replacement services, or browse the rest of our projects.