Balsa wood outdoors - Garden Railways Magazine

IRB: I’ve seen that balsa will not stand up to the weather and constant contact with dirt. You will most likely need to pull it up every year to retreat with Thompson’s. Have a look at cedar or redwood fence boards. They run about two bucks a board, which need not be treated. Untreated, they should last about 6~10 years in your environment. Adding a sealant or preservative will extend their life use. In the long run you should save a pocket full of change over balsa. Cedar ages nicely with a very good-looking patina. Redwood will hold its natural color a bit longer but also develops a nice patina. After building my bridge (redwood) I got a balsa birdhouse (gift) to put among my other buildings. The birdhouse fell apart in just a few months (glue failure), the "floor" had some serious rot after a year, and that was after treating with preservative. The bridge still stands strong with no signs of rot.