This is a quote from another site, purported to be from Johns Manville. It is an early 60's product. Not sure I'd use it.
“An extra strong 1/2″ insulating board sheathing made of bitumen-impregranted wood fiber; comes in 4’x8′ and 9′ sizes; used as a sheathing for exterior walls and as an interior or exterior siding for utility structures; combines exceptional nail holding strength with insulating value.”
“An extra strong 1/2″ insulating board sheathing made of bitumen-impregranted wood fiber; comes in 4’x8′ and 9′ sizes; used as a sheathing for exterior walls and as an interior or exterior siding for utility structures; combines exceptional nail holding strength with insulating value.”
