Re: Little Library- which plywood?
David Weaver
I built one a couple of years ago with interior plywood - If it's heavily painted and you're careful about not making areas on it that will retain standing water, i doubt it will matter too much. the one that I built breathes well - intentionally, so that it won't heat and cool and cause condensation issues.
https://i.imgur.com/zdpl0QF.jpg
I built mine for the neighborhood at the cost of materials, and at first thought about using premium materials but the cost would've been double. (the bigger one on the left - sorry I don't have better pictures of it face on, that's just the side - some of the girl scouts in the neighborhood requested that the sides be inset so that they could do tile mosaics).
I couldn't find a reasonable roofing material (cost wise for one house) so I bought a quart of rubberized bed liner and applied that to the roof so that there were no seams or low areas that would hold water.
As ellis says, most of the libraries are haphazardly built. The small one on the right in the picture was "professionally" made and it's made poorly, but it's small enough that it doesn't really matter. When I was eyeballing the construction of other "professionally" made and sold versions, many were just made of pine dimensional lumber from home stores.
I think paying attention to costs and doing something simple is more prudent - ours are heavily used, but who knows before you put them up? Some others near us in parks scarcely have much in them or get used (when you go back to them, the same books are in them every time). If ours last 10 years, that's great. If they last 5 and need repair, I will repair or replace parts.
if you're volunteering the work, especially if you're donating materials, just doing something reasonable is going above and beyond.