Professional Sash window
draught proofing in London

Sash Window Draught Proofing in London

If your sash windows rattle when a bus goes past, or you can feel a cold draught standing a foot away from the glass, the windows themselves probably aren't the problem. It's almost always the seals — or rather, the lack of them.

Original sash windows weren't designed to be airtight. They were built to slide, which means there's always going to be some movement between the sash and the frame. Over time, whatever sealing was there degrades, the timber shrinks slightly, and suddenly you've got gaps that let through cold air, street noise, and damp. It's one of the most common complaints we hear from people in Victorian and Edwardian properties across London.The good news is it's fixable without replacing anything.

What the job actually involves

We're not fans of overcomplicating this. Draught proofing a sash window is skilled work, but the principle is straightforward: find where the air's getting in, and seal it properly.

Finding the gaps — We go round the whole window systematically. The meeting rail, the side channels, the bottom sill, the parting bead. Some gaps are obvious, some you only find by feel. We don't guess.

Choosing the right materials — Brush pile seals are the standard for sash windows because they allow the sash to keep moving while still blocking airflow. For fixed frames and sills, we use foam or wool seal depending on the gap size and location. We don't use a single product for everything — what works on a tight channel won't work on a warped sill.

The installation — We rout slim channels into the timber to recess the brush strips so they sit flush. Done properly, you can barely see them. The sash still glides, but the rattle is gone and the cold draught with it.If the frames are rotten or the sashes are badly misaligned, we sort that first. There's no point sealing a window that's structurally compromised — the seal won't hold and the underlying problem gets worse.

What you actually notice afterwards

The difference is immediate. The most obvious thing is the quiet — sealing the gaps cuts out a surprising amount of street noise. The second thing is the temperature: no more cold patches near the windows, and your heating doesn't have to work as hard to keep the room warm.

It also helps with condensation. A lot of the moisture that builds up on period windows comes from warm interior air mixing with cold air leaking in. Seal the gaps and you reduce that significantly, which means less mould risk on the timber and the surrounding walls.

From an energy standpoint, it's one of the most cost-effective things you can do to a period property. New double glazing in a listed building is often not permitted anyway — and even where it is, draught proofing the original windows typically gets you most of the thermal benefit at a fraction of the cost and disruption.

Why it matters for period properties specifically

Conservation areas and listed buildings in London have strict rules about what you can and can't change. Draught proofing the existing windows is almost always approved without issue — you're not altering the appearance of the window, just improving how it performs.

We work across all of London's period housing stock — Georgian, Victorian, Edwardian — and the windows, while all different in detail, have the same basic problems. The sealing systems we use are designed to be invisible from the outside and sympathetic to the original joinery. We're not fitting plastic draught excluders from a hardware shop. Everything is recessed, fitted properly, and finished so it doesn't look like an afterthought.

Ensuring proper closing

Verify that your sashes sit perfectly flush within the frame. If they are misaligned or warped, they may need professional calibration or repairs—this often involves retrofitting new hinges or installing specialized beads. Achieving a precise fit is key to ensuring a weather-tight seal while providing the added benefit of significant noise reduction.