Thank you for your inquiry regarding this item from Prime-Line Products. This item fits on 1-3/8 inch thick doors max., most all exterior doors are 1-3/4 inches thick, so that would prevent this lock from fitting on the door. Secondly, this item would not do anything for a single door... it's designed to clamp over a pair of bi-folding doors to prevent them from folding outward into the room, which is how they fold when the door is opened. This item will only work on bi-folding closed doors that measure up to 1-3/8 inches in thickness.
For additional questions regarding this item, or any other product manufactured by Prime-Line Products, please call their toll free number at (877) 649-9740, or contact them by email at firstname.lastname@example.org