I talked to a woman about the plastic eglu runs, if you can't move them, they advise that you cover the run and put down a thick layer of chunky wood chips, not shavings. I can't remember if they were meant to be removed every year or so, but she she said this was a very easy to use system. I have a handful of birds inside at the moment, on concrete. I was hoping to sweep it every day, but it's a bit wet and sticky and just makes a mess, so I'm thinking a layer of straw will be needed after all. The rest of my birds are free range on grass,most is no problem.