I have a great system where I never have to clean the loft out. I only have to clean the nest boxes after the squabs have left the nest.
I keep my pigeons and one large covered run / aviary. The back and one side is solid, the top is waterproof and has a large overhang all the way around to make sure no rain gets in.
The floor of the coop in natural dirt. This is covered with a deep layer of coarse river sand.
Because everything is so dry, the poop lands on the floor and dries up, then gets mixed into the sand. I just rake the lot over once a week.
When the birds are moulting the feathers all collect up in the corners. I just scoop them out once a week also to keep it looking tidy.
Along the back wall are all the nest boxes.. which have mesh floors. On top of the mesh I place nesting material. The mesh floor provides good ventilation, again drying up the poop.
I have one chicken water thing on the floor, stood on some bricks.. to stop feathers and sand getting into it and making the water dirty. I just change the water once a day.
Its really easy to keep them clean like that. I also have 3 long thick oval perches running the length of the coop. As they are oval the bird poop just falls down onto the sand under them. I used to use flat planks as perches, but these get covered in poop, which gets onto the birds feet and they spread it everywhere. The THICK oval ones are much better.
I even let my king pigeons out to fly free when I am about to watch them. They don't go far... but I use this time to give them a pan of water to bath in (about once a week). Then they splash about .. and the coop stays dry, they get clean, and then they fly up onto the coop roof to sunbath and dry out.