All outside doors, windows and other outside openings shall be screened with wire screen or its equal with not less than sixteen (16) meshes per linear inch. All screen doors shall be equipped with self-closing devices and, when closed, fit tightly enough to prevent entrance of flies, mosquitoes and other insects. Window screens shall fit closely enough to keep out insects and be easily adjustable so that they will not serve as a block for the evacuation of patients in case of fire. (Mont. Co. Code 1965, § 89-42.)