interior ceiling/roof sheating?

Hello to everyone. I am finally "coming out of the closet" and posting a my question here for some help. I am finally taking the plunge into building my own teardrop after 1 yr of research, reading, and other various lookups on the T.D.
I printed the Benroy Plans from the site because I like it the best for me. It calls for 1/8" birch plywood for the ceiling/outside roof sheathing. While at H.D. today I tried to locate the 1/8" plywood but had no luck.
My question: Where can I purchase the 1/8" birch plywood? Can I use 1/4" birch instead without it cracking on the bends?
I appreciate all your help with this and I hope to get pictures as I start building the T.D. any other suggestions for the T.D. will be appreciated.
Thank you
Jake
I printed the Benroy Plans from the site because I like it the best for me. It calls for 1/8" birch plywood for the ceiling/outside roof sheathing. While at H.D. today I tried to locate the 1/8" plywood but had no luck.
My question: Where can I purchase the 1/8" birch plywood? Can I use 1/4" birch instead without it cracking on the bends?
I appreciate all your help with this and I hope to get pictures as I start building the T.D. any other suggestions for the T.D. will be appreciated.
Thank you
Jake