Open cell insulation was blown in before New Years! Love it. The ceiling and walls needed no more than 3". Unfortunately, the waste created was too much. They hauled away more than remains in the tiny house. Had a I known this, I would have found another insulation, since the waste was horrendous and could possibly been chopped up and blown into typical home ceilings, for example. Very little trimming was required, and have used a curry brush (used for combing horses) very effectively And since this insulation is so soft, you can push it with your hand and compress it enough to install the planking in most places.