February 6, 2011 at 10:01 pm
#716590
wsgolfer
Member
Actually, R13 is typically used to retrofit old exterior walls. In older homes, like mine, exterior walls were framed with 2″x4″ lumber, which is really only 1.5″x3.5″. So the wall cavity in such walls is only 3.5″. Most R13 batts & rolls you see in store are 3.5″ thick, and are meant to completely fill this cavity. In new construction, exterior walls are required to be framed with 2×6 lumber, which means a 5.5″ wall cavity, which can easily be insulated to meet new code.
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I suppose you could use R13 fiberblass for noise abatement in interior walls, but I’d recommend Roxul Safe’n’Sound for that.