Is this a sheathing?

This portion of the siding is butted up with hardi. Is this a kind of clapboard siding or type of sheathing? 1981 Home


Looks like “Masonite” composition (cellulose product) clapboard style directly nailed to studding through a tarpaper WRB (weather resistive barrier).

What do you mean “butted up with hardi”…is it clapboard style Hardiplank or commercial style Hardiboard? If it is the Hardiplank ,they may have vertically strapped the exterior for leveling purposes and then installed the horizontal cement clapboard.

So it does not appear there was any sheathing board used as to my “butted up with hardi” term.

It was definitely clapboard style hardiplank.