Window Jigsaw

The time has come to start assembling the jigsaw that is the stone mullions for the front window and rear patio doors. As this photo shows, the bottom layer of the window comes in three sections that are set into the stonework, and distanced from each other using metal spacers :

The spacers seem to have a dual function in that they also join the components together and will probably also be the locating lugs for the vertical mullions.

In the rear patio door the components are again installed in sections. Today the first vertical block was placed on each side. As this photo shows, there are metal tie barts to link in with the stonework, and two holes on top that presumably accept some form of peg to locate the next section up :

I imagine getting this to stay vertical, and correctly aligned, was a tricky job. The plywood plank to the left is cut to the exact width of the opening and is wedged between the two to help to hold them up while the mortar goes off. The blue clamp also helps with this.