The topic of insulation is widely debated across the blogs and forums on van conversions. The major factors of debate include efficiency, moisture management and cost. There are two major categories of insulation to choose from, spray or roll. We decided to begin weighing the options for roll insulation as we did not want to tackle the process and mess of applying the spray insulation. Before getting into the specifics, it is important to understand the concept of R value. R value is "the capacity of an insulating material to resist heat flow. The higher the R-value, the greater the insulating power." In order to fully insulate the Ford Transit 148 wheel base, we will need roughly 250 sq feet of insulations. After some initial research, we narrowed our options down to Thinsulate, denim or natural sheep's wool. We had excluded any fiberglass based insulation as we were nervous of any health risks associated with spending a lot of time in a small space with fiberglass particles floating around.
Thinsulate is a synthetic material with hydrophobic properties, meaning the fibers resist moisture, mold and mildew. Moisture management is an extremely important factor when evaluating insulation as you don't want mold and mildew to form behind the walls, ceiling and other finishes. The Thinsulate insulation comes in rolls of various sizes, but a standard of 1 3/4" thick at an R value of 5.2 for a cost of $2 / sq foot. Our overall feeling on Thinsulate was an expensive product for an average R value.
Next we began to investigate denim insulation. Denim is derived from recycled textiles (nice!) and is readily available at most home improvement stores. The R value is great at R13 for a 3.5" thick product and it costs as little as $.80 / sq ft. The one downside to denim insulation is that it naturally absorbs and holds moisture. In order to protect mold and mildew, you must cover any areas of insulation with a plastic vapor barrier. We did not want run the risk of the plastic wearing over time or getting a hole, so denim was scratched from our list.
The last option we explored was natural sheep's wool insulation. Sheep's wool insulation is naturally breathable and able to absorb, retain and release moisture without impacting insulating performance. Sheep's wool is also naturally flame retardant and will not disintegrate over time from vibration, which will happen to both fiberglass and denim. This wool insulation is rated at R13 for a 3.5" product and is priced at just about $2 / sq ft. Great moisture management, reasonable price and all natural...we were sold on the natural sheep's wool. We shopped around and found a USA sourced and made product at Eco Building Products. We wanted to make sure we weren't missing anything, so called Greg at Eco Building Products and he was incredible knowledgeable and helpful. We have been very happy with the insulation and glad we took the time to do our homework on this one! We will have a future post of installing the insulation coming shortly.