I've been lucky enough to get to use a decent sized shop for a short while. I've always wanted to build boxes for screetch owls, kestrels, and flickers to add to the wildlife habit modifications here. I've already installed a number of birdhouses, lizard refuges, foodplants, perches, feeders of various types, and water baths. Below are some photos of the current state of my kestrel / screech owl / flicker boxes.

I started with the plans from Nestwatch (Cornel). However the flat roof situation didn't sit well as last year we had the wettest year in recorded history and this year we are outpacing that. I think we're about 14 inches above normal. Anyway, I modified to a 15% slope for the roof and sides and had to bevel the top edge of the front panel in order for them to fit well. This brings me to a bit of a predicament. Those same slopes, while good for shedding water, make a top-hinged side for cleaning nearly impossible. I'm considering making the front of the box the clean out panel. Since writing this I've seen similar efforts on YouTube. Thoughts?

All that said, the back panels are longer for mounting. Now that I know where they are going. I may need to modify how the box is placed on the back panel. I'm planning on putting the boxes under the eaves of the higher roof looking out over the lower one. That will protect them quite a bit more than an open metal pole which could end up as a lightning rod. Has anyone done something similar?

I'm having trouble finding either solid brass or stainless steel Screw-in Square Bend Hooks. I'd rather not have to replace hardware later so would prefer to have free things to worry about.

Rather than use screws in the top of the opening side (which will probably just be the front of each box) I'm thinking of using a brass piano hinge. The gap I mention next might kill that idea. Thoughts?

If I make the cleaning side the front, I'd probably have to move the front panel down a quarter inch or so in order for it to swing upwards. If I did that, it would leave a gap right under the roof when closed. Ventilation? Since I wrote this, the aforementioned YouTube video below seems like they did the same thing.

https://youtu.be/ke1fpL_Dj8Q

Here are the boxes. Two styles... One for kestrel/screetch owl and another for flickers. Hole size is the same. Kestrel box is more girthy while flicker is taller and slightly more narrow.

After a long delay, they got installed today. I put them hanging under the third floor roof overhang (standing on the second floor roof). I shoved in a few inches of poplar shavings for the nest floor. This allows me easy access to service the boxes while keeping them away from people and prying eyes. Now, fingers are crossed for coming breeding seasons.

I just found this thread today. I like your idea for letting the front open for cleaning.

For me it was easier because I'll be standing on a roof in order to service the box. The folks who run kestrel box trails recommend opening from the side as you have fewer options when you're on a ladder and it is safer in case the chicks try to bolt.