Always order windows by name specifying blindstop or overlap.Always give exact opening width and height.On windows for blindstop installation, we will cut back under opening size 1/8″ on width and height.

Example: Actual size of storm window to fit a 36″ x 55″ opening for blindstop installation will be 35 7/8″ x 54 7/8″, including sill expander.

On windows for overlap installation, we will add 1 ¼” to opening width and ¾” to opening height.

Example: Actual size of a storm window to fit a 36″ x 55″ opening for overlap installation with be 37 ¼” x 55 ¾”, including sill expander.

NOTE: Columbia does not recommend the use of storm windows for porch enclosures.

WIDTH “W”: Inside casing to inside casing equals opening width.
HEIGHT “H”: Inside head casing to sill equals opening height.