My backyard is higher than my neighbor in behind me. To keep the ground level, there is a three foot retaining wall at the back of the yard, which is only a few inches from the fence. The wall is built from 6x6's, and is not normally visible (even the top of the wall is hidden by bushes and flowers in front of it.
The problem is that the 6x6's appear to have started to rot. I imagine they were put in place when the house was built 25 years ago. This year, the neighbor's want to rebuild the fence, so I was thinking of replacing the retaining wall at the same time to give easier access. It doesn't have to be pretty, just functional, and as long lasting as possible (and preferably fast to build without breaking the bank). The wall is about 25m (around 90') long, and I live in Canada, so there's lots of freezing and thawing going on.
I'm wondering if I should consider concrete, brick, or wood again (and what the advantages are), and if anyone has any advice that I might not have thought of.
Thanks
John