Hempitecture HempWool is made from 92% industrial hemp fiber. Because it’s mostly plant based, it’s non-abrasive and non-toxic It comes in 16 and 24-inch batts with R-values of 7, 13, 20 and 28. Working with hemp wool requires the eye protection and dust masks typical of any insulation job. It’s best to cut the material with a table saw and an angle grinder.