I have a customer that wants me to build a small outdoor shed for her. Several years ago she had a large barn built that is covered on the the outside with board and batten hemlock. Seems to have held up very well and aged to a nice color. It has no finish on it and is about 12 years old now.

Does anyone have experience using hemlock for barn or shed siding? If so, what's the life expectancy if left untreated. Both hemlock and eastern red cedar are readily available here. She does not want any finish on it at all.......prefers the natural weathered look over time.

Thanks for any info that you may be able to provide.