Box sash windows

[meccarroll]

It's not that it's a bad idea it's just not how it was done. If it was proof against it ever rotting I would consider it but after 100+ years these windows can basically turn so dry and twisted water can penetrate In a multitude of spots. Making them with a housing is my favourite bit oddly it's just a rock solid joint with the sizes set by the inside of both housings.

I totally understand why the original sliding sash windows used a wedge and groove at the junction between the pully stile and cill.

The wedge tightens up the joint to prevent shrinkage and stop water running in the groove but over time shrinkage plays it's part and water inevitably makes it's way into the groove and the rot starts. It was known many years ago to be a weak point and the wedge was a form of preventing shrinkage opening the joint.

It is normally only the corners of the cill on a sliding sash window that go rotten and it does usually take some years to happen so it's overall not a bad design.

 

[Jim mcgrath]

Thanks for all the photos. There’s a good Youtube video where he demonstrates making the housing in the cill for the pulley stile to sit into. It’s titled “how to make box sash windows in oak part 1” (skip to about 13.40)