I'm learning here too so it will be an experiment based on my previous experience.
The house part is deffo enough space to sleep 24 6-9 week birds on roosts. I'm basing this on a 100% hatch from my Octagons and in reality, it will be less birds. My broader concern is how long 6' x 4' of grass will last 24 growers. But I will only know that by experimenting and it may mean 3 moves a day or one move every 3 days.....
The roosts will be 2x1 batten on their sides and with the edges planed off. I have found that this age of bird likes this profile to roost on through nothing other than trial and error so will go with that. The 2x2 mesh will be stapled below this. The purpose of this is to stop the birds getting down onto the floor of the house bit and getting mangled when I drag the brooder along. I want them in there, safe and roosting when I move it. In my previous attempt, I got a bird caught up in the dragging and although he is fine now, I nearly had to cull him there and then. Not nice. If they do get their legs though the mesh, they will still be way off the deck so no harm while dragging. I can't see a 6 week grower getting through a 2x2" hole. Also means they are not treading in the droppings they lay down of a night. That's going into the soil as pure fert.
Also, at night, I want them to be roosting, not on the deck. This is important training for later and some say it should start from 10 days.
More pics should clarify things. I'll add some with the birds in too, maybe tomorrow if I get it finished.