Is this to be a permanent house? If you mentioned how many birds, I missed it. For a permanent house, A#1 floor of choice is cement, followed by wood planks, followed by dirt, which comes in dead last. That has been true for at least 100 years. Even with deep litter, dirt will foul (fowl?) over time. The only way to clean it is to remove it. Deep litter will prolong that, but it gets there eventually. Unless situated on a site that is well drained and high and dry, dirt floors can be wet, which comes to the forefront in winter, with high moisture issues leading to frostbite. Dirt floors are an open invitation to rats. Advantages of cement are it is built so as to be high and dry (built elevated from surrounding land on an elevated, well drained site), it is sanitary, and best of all, provides protection from digging predators, including rats. ON an uneven site, wood floors can be used for the same advantages. And you can still use deep litter on cement floors, which also makes them easier to clean out. On the other hand, if this is portable housing that can be moved, then dirt on a well drained site, or wood floors are OK. Having said that, I have two houses, one with wood plank floor (pressure treated lumber which gets wet and stays wet if the litter gets wet) and dirt. Dirt also stays moist when it gets wet, but house is well ventilated and underlying soil dries out over time. But both of mine were built to be portable. House with board floor is rat proof, more or less. A mouse might find a way to sneak in. House on dirt is not rat proof. I've not had rats, but have had mice and the mice tunneled their way in and were living in tunnels under the litter.