On May 11, 4:57*pm, aemeijers wrote:
RicodJour wrote:
On May 11, 6:02 pm, mm wrote:
With a rail fence, three rails will each bear as much load as the two
rails would,

Each? *Not quite - each rail in a three rail fence will only have to
take 2/3 of the load on a rail in a two rail fence.

and the load on the posts will be 50% higher.

The only difference is the weight of the rail and the additional
fasteners. *Not sure where you get the load difference numbers.

R

Nobody else said it, so I will- how tall is the damn fence? For a short
fence, 2 rails may be fine, but for a traditional 6-foot privacy fence,
we always used 3. We also usually used alternating-side pickets with an
overlap, so some wind could still blow through. Plus, that way, no
arguments about who gets the pretty side.

--
aem sends...

6 foot tall privacy fence. All such fences in the area have 2 rails,
and seem to be none the worse off for it. The big problems are post
rotting and leaning as well as fence sag due to the 2X4 rails being
placed with the short dimension vertical.