faux bois steps by lauraknosp, via Flickr
It's concrete!!! They use a mold created from old logs to make the siding! Resists mold, insects, fire, etc! Something to think about!
Google Image Result for http://www.nps.gov/nr/feature/hispanic/2001/Tree.jpg
FRAYAGES DE LA DÉRIVE: ROCAILLES FIN-DE-SIÈCLE ET POÉSIE DES RUINES
Faux bois arbor
Concrete arbor that lasts decades
Real live treehouse!
French Vintage Faux Bois Animal House