An Ordnance Survey cut mark in the UK. The term bench mark, or benchmark, originates from the chiseled horizontal marks that surveyors made in stone structures, into which an angle-iron could be placed to form a bench for a leveling rod, thus ensuring that a leveling rod could be accurately repositioned in the same place in the future.
The forces that cause windows to leak fall into three categories: house design, installation, and maintenance. Turning to the wisdom of industry experts, we can identify nine of the most common errors that occur during window installations, which can lead to window leaks â and now you can too.
More than likely this may just be mildew from condensation and air infiltration. Mold and mildew develops on your window sills because the window frames are not thermally broken.This allows condensation to form on the inside of the frames during cold days and winter months. 1  The formation of condensation could be an indicator that your humidity level inside the home is too high.