Sealed With A... Can?

In this picture, Tom is sealing the cracks between the panels with foam insulation. He drills an access hole, fills it, drills another, fills it, all the way along each seam. Anyone who has insulated knows that if you miss a spot, you've missed it all. So foot by foot, space by space, wall by wall and roof panels too, all the seams are sealed up tight.

XPS has a high R-value (5 R-value per inch of panel). This means a very well-insulated envelope that should heat and cool with minimum effort.