I need a bit of advice.
I'm a 69 year old, very out of shape woman, and a very poor carpenter, but I build my own coops and pens anyway.  And they work fairly well.  I'm currently finishing one that I've placed in the "ell" formed by our small newly-renovated 10' x 20' Dutch barn and its 10' addition (my new incubator/
brooder room).  The barn forms the back and one side of the coop, which is only 2' x 8'.  I framed the botom and have filled it with Quickcrete so predators can't dig under it.  I took a shortcut (don't laugh) with the Quickcrete.  Reasoning that the bags will set up if left anywhere too long, I just had my husband pour it into the framed bottom, added water, and stirred it around some.  (I have limited strength and stamina!)  I did mix the last couple of bags properly in the wheelbarrow to finish off the top. Those bags are heavy and it's a lot of work!
What I need the advice on is probably a major mistake I made in purchasing materials for the top.  The roof of the barn proper will drain about two feet down onto the roof of the coop, which I've slanted at a 1" per foot rate.  I just realized (wasn't paying close attention--just bought by sight) Tuftex Deck Drain instead of material intended for roofing.  Am I wasting my time if I use this for the roof?  I'm just at the point of installing it.  I don't think I can return it to the store, as it has been sitting outside for a couple of weeks.    The reasonable side of me tells me I need to go back to the store and buy tin roofing material, but the hopeful side wants it to be workable as is.  If I need to get the tin roofing, can I use the deck drain fasteners with it?
I've been very careful about constructing this coop, so it is neatly built and quite sturdy, and I'll add a small outer pen to it so the chickens will  have more space to run around in.  I'm normally happy with my pens if they just do what I want them to do and hold up for a few years--they don't have to be all that pretty.  Les and Teva can verify that.  LOL
Now that all the men and women who know how to do thngs right are rolling on the floor laughing, someone please let me know what I need to do and give me a LITTLE encouragement in spite of my ignorance.