Understanding how much wool to put in your wall, ceiling or floor cavity
Your insulation should be as thick as your build will allow. We recommend filling to full cavity depth. We typically see 2” batts used across the van by layering and peeling the batts to the right thickness. Some spaces more, some less. There is a surprising amount of room in the headliner. Measure the square footage and note the desired depth; you will then know what to buy and how much. Windows are often omitted from total square footage needed, we would argue windows should be insulated by making insulated curtains or the like as windows have almost no R-value. Each box of 2" covers 100 sq ft.
Check out our Van Insulation video which has a great description of thickness desired.