providing a structure including framing members and {TAIL ~ a sheath} forming at least one cavity having {HEAD ~ a known depth} 
providing a structure including framing members and { TAIL ~ a sheath } forming at least one cavity having { HEAD ~ a known depth }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD