If you want to make it even more predator proof you can go to a company that does on-site gutter replacement and get a piece of brown coil stock they use in making gutters. You can wrap this piece of metal around the back of the box and the 2 sides - attach it with screws and drill several ventilation holes in the 3 sides you have covered.. The length of your piece of metal should equal the width of both sides of your box plus the width of the back of your box. The height of your piece of coil stock should be about 7-8 inches above the top of the box at all points. Then attach a piece the size and shape of the roof. If you put metal on a wood duck box, you increase the inside temperature; especially if the box is in the sun for most of the day. Consequently, metal-clad boxes are best if placed in shady locations or in locations where it is shady during the hot afternoon sun. One suggestion … if your box goes unused, try attaching it to a end corner post on your dock next year (still use the post you have and a predator guard). It has been my experience woodies really like nesting boxes that are placed over water. Just a suggestion; hope you get a nester.