Henhouse questions for deep litter, DE question

All,

I'm partway through our coop build, a stacked henhouse over a fenced run that is being designed to accommodate deep litter. I have a few urgent questions about this as I attempt to finish things and get our girls moved in, which we hope to do tonight:

1. Bottom line up front: how do I prepare the plywood surfaces of the henhouse if using deep litter, to maximize longevity of the structure? The details: the henhouse is a 1/2" plywood box design on 2x4s. The box is built (see attached photo), roof is mostly done, but the insides are not yet done. Cutouts at 12" above the floor have been incorporated for the laying box and chicken exit, to accommodate the foot deep bedding used for the deep litter method, and then another hatch is cut lower that will be opened to clean out the composted bedding bi-annually / annually. Not all doors and windows are in yet, we're cutting those in next. Since we will have this damp mess of bedding year-round with the DL method, do I want to line the plywood floor with something? If so, what? Should I use a spare pond liner (heavy duty rubber sheet) that we have? Should we put down linoleum, or something else specific? Do I drill holes in the floor to allow bits or fluids to drop through? I don't know if I need it waterproofed or performated on the bottom and sides, to prevent rotting of the wood.
2. I have heard that the use of diatomaceous earth is no good for the deep litter method to prevent killing off beneficial microorganisms, which makes sense. But can I use DE in a separate dirt bath station underneath the henhouse, in the fenced in run? In the absence of guidance, I was going to use a mix of DE, sand, ash from my charcoal grill, and topsoil.
3. What kind of ground material is preferred for that run area at the base of the structure? Just leave it as dirt, put in some mulch, bring in gravel? This year is a test run and if we love the placement and design of the coop, I will pour a pad next year and anchor it down. But for now, what's the best flooring on which the coop will sit, both for longevity of the wood (only the bottom rectangle is pressure-treated, the rest regular pine) and for the chickens' enjoyment?

1. Yes, put down a liner. In one coop I used some old sheet vinyl that I found in our attic left from a previous owner, and for the second coop I bought a large heavy duty tarp. In both cases I ran it up the walls about 6" but really should have done it a foot.

2. Yes, DE is fine in the dirt bath (though useless IMO and some people do say it could be bad if breathed in while they are bathing).

3. Leave it as dirt unless you encounter drainage problems, in which case you can amend it accordingly. They are going to scratch it all to heck regardless so save yourself the trouble. When you pour a pad what are you planning to put over the pad? Soil?

For the very bottom, just leave it dirt. Throw in gardening waste (non poisionous of course), the occasional bag of sand/dirt/straw/hay, and shovel it out as needed. Use this to fill low spots, or just spread evenly on your lawn.

Excellent, I might be on the right track then. I will have a look at that pond liner and see if it will do the trick. I was going to line a raised bed planter same size with it but I decided not to, and have been trying to figure out what to to do with this thing. It comes up about a foot on the sides for a 4'x8' structure, same as the bed I built coincidentally.

I might go easy on the DE. I read through a lot of the 2000+ post DLM thread and it's been a mixed bag, people said that DE in the deep litter really doesn't cause too much trouble, others said it's bad, more of the former than the latter. They also said maybe put in a few shovels full of dirt if you have a lined henhouse to try to jump start the actual composting, since dirt floors allow the good bacteria to get up into the litter, and keep the moisture levels up just a bit. I didn't realize that the DLM didn't necessarily guarantee composting in-place, and might only be there to keep the waste dry and compact, and it's just a slow process of building up that has about a 1 year timeline until it's time to start over. I want the composting to happen, so hopefully I can figure out something that works.

If we did a concrete pad, I actually didn't know what the ground level should be on top of that. Maybe sand? If it needs to be something organic, it seems like pouring a pad would just be silly, since I'd need to put something natural back down on top anyway. Less work is okay in my book.

With deep litter that has actually composted (as opposed to just getting packed down but staying dry), can you use that compost right away in the springtime, or do you have to mature it further in a separate compost pile? And what about if it didn't really compost but just absorbed waste and was just barely moist enough to keep dust and rot down - how long would that take to compost outside of the henhouse when we wanted to use it? I'd like to avoid having to wait months for compost that I need in the springtime.