Timber Science

Joinery joints are rarely visible once a window or door is installed, but they carry most of the structural load. When they are designed properly, the rest of the product can move, breathe and age without failure. When they are not, no amount of surface finishing or hardware can compensate for what is happening inside the frame.

Timber is often described as “stable” or “reliable,” but that doesn’t mean it’s static. Every piece of wood continues to respond to its environment long after it’s been milled, planed and installed. It absorbs moisture, releases it, expands, contracts and slowly adjusts to seasonal conditions. This movement isn’t a flaw. It’s the defining characteristic of timber—and the reason joinery design either succeeds long-term or starts failing within a few years.

In many period homes across Cornwall and Devon, the timber itself remains in excellent condition. The problem is usually worn sash cords, loose joints, failed seals or years of paint build-up preventing the window from closing properly.