"mike" wrote in message
...
I notice the old fences around all have 2 horizontal rails for the
boards to attach to. I've also noticed that new specs often show 3
rails, without comment. I'm thinking that this might be due to the
fence boards being much thinner than they used to be.

I like to place my rails long side vertical, so I don't get excessive
sagging over time. But I'm thinking that unless I expect the fence to
see hard wind loads or other severe attacks (kicks, etc.), 2 rails
might be enough.

Any thoughts?

I've seen fences installed after Huricane Ike hit down here in Houston and
the ones with two rails have boards warping and bowing like crazy. I mean
every board is going a different direction. This is in more than just one
neighborhood so it looks like the quality of fence board in general has gone
down. 3 rails (top middle and bottom) may help with this warping issue.