Why don't you just keep the dirt floor? Thats all I have ever had.
If you don't live in the Pacific Northwest, it's hard to imagine how incredibly wet everything is. No matter if you live on high ground or near a wetland (as I currently do), you constantly battle mud, slippery clay, mold, and just plain ol' water underfoot. Unless your chickens are housed in a weather-proof large barn and never go outside, having something on the ground that drains well is a must.
I ran into people saying they would never put their animals on sand on another forum. They just couldn't understand the need...it's crazy wet here! LOL.