"straydog" wrote ' in part ' in message
...



..............(the moisture barrier was,
believe it or not, roofing felt) and I
noticed no moisture residue or short-term
rot (house & siding were about 20 years old)
and I mention this as an FYI.

When you say 'Moisture barrier' are you referring to the "roofing felt"
being immediately under the exterior clapboard cladding/finish?
If so that would not be a moisture barrier; those are installed on the warm
or inner side of a wall or ceiling, to prevent warm (and therefore moisture
laden) house air from seeping out and condensing inside the walls and
insulation.
What should have been used under house siding AIUI, back before today's
'Type style' products, would have been some kind of permeable barrier which
would have allowed moisture that did get within the wall to have 'breathed
out'. Maybe your roofing felt would have met that requirement?
I have used 'Building paper' in such a situation and plastic sheeting
internally on the walls etc. as the 'Vapour Barrier'.
Curious.