[SML] roof question

[Bill Conner]

Foam is not very good at stopping sound energy since it's rigid and
tends to conduct it.  And someone has included a vent space they think
will stop ice dams (don't get me started on that fallacy) so design is
complicated, because the vent space should be above the insulation.
Ultimately I think a heavy weight asphalt shingle and maybe add
another layer of ply for mass would be best choice.  Should be fine on
4:12 by most codes and by most manufacturers.

If you want to add insulation, either do that under the base wood deck
or hire a real roofing expert - not a roofing contractor or sales rep
- and follow their recommendations, but don't put foam on top of the
vent space.


-- 
Bill Conner Fellow of the ASTC