It rains a lot here (Hilo, HI) and my yard does puddle when it rains for days. Pullets (2 RIRs & 2 EEs; 12wks) are sleep in their coop that's in my patio. In the mornings they stay in the mobile run which I move every 2 - 3 days, late mornings I let them out to grub the yard & they return to their coop for bedtime. Hubby will be building a 8 x 12 walk - in run (with roof) on the high ground that is grassy but I know it won't be for very long. We plan on draping sun shade over the wire to help prevent the rain from getting in, allowing ventilation. Even thought of hanging shower curtains, I'd close when we have our rain storms (get a lot). The area is also protected on 3 sides with shrubbery, their house (plastic) will be raised off the ground. I was sold on the sand until I read up about DLM now undecided :(
Playground sand I can find at Walmart but read not the best to use, that Construction Sand (courser) on top of gravel is the best drainage. Playground sand would be easy to use a kitty scoop for poop but Construction Sand, I'm not sure. We'd have to get it from the gravel yard, renting a truck & hauling by wheel barrow to the backyard.
Pine shavings & grass clippings for DLM, told hay although some say straw (?), would be easier to purchase at the feed store & transport. The "old" stuff I'd put around my surrounding plants. Thinking out loud leaning toward DLM, again, maybe start off with DLM and if it don't work go to sand? I know it's all preference but just sounding out for any other arguments.
All the advice & information on this site is ever so helpful :)
Hilo, HI is extremely wet and humid. I have been there twice, and my son lived there last summer. He said even his coins were rusting. It is probably one of the wettest places in US with the highest annual rainfall.
So if I were you, I would not use sand, because the chicken poop would just get mushed into the sand to create a smelly paste. Sand is not decomposable so you can't even get rid of it easily. A lot of people like sand, but it is most suitable for areas where the weather is not too hot, too cold, or too wet. The substrate below the sand bedding should be permeable, or the condition is such that the sand bedding can remain dry. It also needs a very dedicate owner who wouldn't mind sieving poop daily, rain or shine.
Use DLM instead in a covered run would make your life so much easier. You do want your run shielded from most of the rain, so the DLM has a chance to obsorb to wetness and odor. A roof with wide overhang is good, also shield off only the lower 12" of the run, but not the entire side. The wide roof overhang will help shielding the top half of the run. Good ventilation is very important especially in a hot and humid climate. You can put in grass clippings, mulched leaves, wood shaving, etc., basically, any organic materials. I personally don't like straw and hay due to concerns with harboring mites, so maybe try to start with your yard waste first. Rake the DLM occasionally in the run to keep the moisture evenly distributed, add more material if it starts to smell a bit or the bedding layer is wearing thin. Dump it out to the compost once or twice a year to make top soil for next year. It is extremely easy. I only scrap the poop boards daily, dump it to the compost bins. No other maintenance needed in the DLM runs.