Just two pics of this crawlspace.

This is really the ultimate in High-Performance Construction as far as crawlspaces are concerned. We recommend the use of a mechanic’s cart when working in a crawlspace like this. Your knees with thanks us!

It is important to note that when you insulate a crawlspace wall like this, with individual pieces of foam, it is a major pain in the neck, it is messy, tedious, and the end result benefit is only cleanliness if you actually clean up. You see, if we foam everything, it will be initially and forever a bit dusty and overspray droplets will be everywhere but then it will stay about that dirty over time. When you do foam board, or piecemeal insulation, you need to ensure there are no holes for pests, even the tiniest bugs, and zero light getting in anywhere. A sliver of light can support life. So what we find is that it is hard to seal the insulation to the foundation: the foundation is not flat, not straight, not smooth, not well-lit or accessible…

We often see our competitors trying to wrap corners and get continuity with this foundation insulation but miss the actual seal in so many areas. It would be like carefully putting on one shoe and ensuring the perfect knot, and then not even wearing the second shoe.

We believe the crawlspace goal should be air-tightness and many that are leaky are humid, dirty, and the problem is the missing seal between the ground liner and the wall-board. How do you seal the ground liner to the wall board and keep air from escaping behind the wall-board? It is too hard to seal behind a piece of foamboard with the floor, the ground, the other walls in the way… spray foam is the way, especially when the geometry is tricky. We have troubleshot sealed crawlspaces that were wet, and the dehumidifier died, and instead of the problem getting bad slowly, it got bad quickly, because there was a pretty rapid transfer of ground vapor to inside the crawlspace and the homeowner liked their home COLD. Often the solutions needed for air-tightness to be achieved are obvious when we install our construction lighting.

I would rather have an absolutely air-tight crawl, with full illumination, and zero insulation, than any leaky crawlspace with lots of insulation or messy insulation.