I'm putting up some wood board and batten siding on a small barn, hoping to let the raw wood turn grey over time to look old. There is a lot of conflicting advice online about how to nail/install the boards, plus what species of wood to use if I want it to weather to a silver/gray finish. What's your advice?
Board and batten siding has been around for a long while, which is probably why there are so many differing opinions on how best to install it. I can't think of a better looking wood siding style to use on a barn or an out-building, and just thinking of its undulating profile and the rustic appeal of aged siding boards that have weathered to a gray patina reminds me of all the old barns that I have stopped to gawk at over the years.
Unfortunately, it can be difficult to replicate the honest beauty of an old building that has aged gracefully, as you rarely know all of the details of the original construction, not to mention the problems of creating a "finish" that has been born by 50-75 years of exposure to the weather. More than once I have opted for unfinished wood siding, only to be disappointed when the weathering created a mish-mash of of black and gray splotches, instead of the hoped for consistent silver color. Perhaps I am not patient enough to let nature do its work, but in general I never leave exterior wood unfinished anymore.
If you want to replicate the look of an old barn, then you could either purchase actual recycled barn wood that is already weathered (very expensive), or try your luck with a semi-transparent gray stain or one of the many weathering "recipes" found online (ie.,vinegar and steel wool).
In my neck of the woods, cedar is the preferred species of choice when installing wood siding, but pine, oak, or fir are also used. More important than species, is the cut and quality of the wood. I do not work with fresh-cut green wood, as it is unpredictable and prone to cracking and splitting over time. When installing the boards, I set 2 nails every 24 inches into solid horizontal backing, leaving about 1/4-inch gap between boards. I then cover the gaps with 2-inch wide battens, making sure to nail them through the gaps and not the underlying boards.