My leaded windows are drafty. Can that be fixed?

Drafty leaded glass is a real problem, especially in a Toronto winter, and it's completely fixable. The right approach depends on what's actually causing the draft.

Why it's happening

Leaded windows are sealed with linseed oil putty that fills the space between the glass and the lead. Over decades that putty dries out, shrinks, and eventually cracks or falls away. When the putty fails, the seal breaks and outside air comes straight through.

In worse cases the lead itself has pulled away from the glass, creating actual visible gaps. That's a structural issue, not just a sealing one, and it needs more than re-puttying.

Option one: re-lead and re-putty

If the lead is in decent structural shape but the putty has failed, re-puttying can restore the seal. If the lead itself is deteriorated, a full re-lead replaces both at once. After a proper re-lead, a well-built window should be close to draft-free.

Option two: encapsulation

If you want to eliminate drafts permanently and improve the thermal performance of the window at the same time, encapsulation is the better long-term answer. The original panel gets sealed inside a modern thermal glass unit. It performs like a double-pane window. No drafts, significantly less heat loss, no ongoing maintenance of the putty seal.

For windows in exposed positions, or front door panels where drafts are a persistent issue, encapsulation is almost always what I recommend. For more sheltered windows where the lead is otherwise in good shape, re-leading and re-puttying is often enough.

How to figure out which you need

I'll look at the lead, the putty, whether there's any bowing, and give you a straight recommendation. Both options are solid. The right one just depends on your window and what you're trying to get out of it.