Thermacell provides a window sill in lengths of 2.5m to suit the 150mm and 200mm blocks.
The thickness of the sill is 80mm. As per the photograph, the sill should be placed across the blocks after they are filled with concrete, and the window frame is then placed on the sill.
Note: Please allow for the 80mm thickness of the sill when calculating the window height.
The weight of the window is more than sufficient to secure the window sill to the wall.
The window sill section that protrudes from under the window is later rendered using fibreglass mesh set into the render.
The end result is very strong and provides a great-looking finish.