Why is there a steel spring on the Shimex?
Structures tend to move a little because of the humidity in the studs, or various other reasons. If you use solid shims, they will either become loose or tighter. When they become tighter, a load transfer may occur directly on the window or door jamb. The steel spring acts as an absorber. It compensates for any movement by substantially reducing the load transfer and preventing any binding or squeezing of the moving parts such as window sashes or door slabs. The anchor strap allows the jamb to float in the rough opening so that you are free to secure the unit by fastening screws through the anchor strap. We recommend using fibreglass insulation all around the unit to allow for compression and expansion of the insulation.
