Size of "rails" for them to "sit" on

[DaveK88]

All I did was use a 2x4 flat side up.

 

[NCVic]

Again, thanks everyone for the great info. Wondered how to keep the excrement out as the store sells uncovered nesting boxes. Saved $9.95 on that one! Also will make construction much easier. Will try to monitor the site and get more great ideas for my coop as I am sure it will continue to evolve! Do not know how to post pics, will look for that area too!
Thanks again