When our house was built 31 years ago, the foundation wall was sprayed with foam on the outside to insulate it. This material was neither thick nor particularly durable. We’d offset these weaknesses by insulating the inside of the crawl space some time back, but there was still a section where sunlight was breaking down some of the old exterior foam, bringing it down to a thickness of zero in places. Ugly and cold, I’d think each time I walked by it. And so it made it onto the Home List.

It is a pain in the butt to fix this problem, which may be why I only thought about fixing it for a couple of years. The solution is to dig a ditch two feet deep along the wall, put in panels of two-inch thick, two-foot wide blue foam insulation, and cover it with foundation flashing and dirt.

Sun-degraded, old exterior foam insulation.

Excavating to solve the problem.

I don’t mind digging; it’s easy to see progress when you’re making piles of dirt. But few jobs are trouble free. My first problem was finding the right foundation flashing. There was none in town. You need a special type to cover the enhanced thickness of the insulated foundation wall. Thank goodness for All Steel, Inc., who happily custom made just what I needed, fast and at a fair price.

I can dig it.

With the flashing and the blue foam boards in hand, it was just a matter of puttering away until the ditch and the foam were level and ready for the flashing.

Quick — hammer it all into place while it’s level.

Once things were in place, a little dirt held it all there while some quick work with hammer and nails locked it all up tight. A little more work with the shovel got all the dirt back in place, and it was another quick job to rake it smooth and plant grass seed.

Done. Raked, seeded, and — bonus prize — an unexpected carpenter ant barrier, too.

Not long after it was all done, I realized that there was an unanticipated fringe benefit. Each summer we protect the perimeter from carpenter ants to prevent the establishment of a colony in the walls of the house. With the physical barrier of the new foundation flashing, they had no little holes left to go scouting up into behind the siding where it met the degrading old foam insulation. An unexpected win for us and an unmourned loss for the ants.