Extreme home insulation saves more than heat, it saves money.

Extreme home insulation starts by reducing heat loss through the ceiling.  That heat goes into the cold attic in an effort to heat the world.  The ceiling loses more heat than any other portion of most homes.  Heat always rises which explains why the ceiling has the best opportunity to lose the most energy.    We designed our home for nine foot ceilings throughout.

The shop extreme home insulation job brought special challenges.

We built the shop to be large enough to store a 40 foot diesel motor coach.  To do so, a portion of the shop ceiling must be 16 feet off the ground.  Accordingly, the coach also needed a 14 X 14 foot access door.  We chose an insulated  door with a R175 rating built by the Overhead Door Company dealer.

We used high density spray foam to insulate the two vertical vaulted ceiling walls on either side of the vaulted ceiling.  The insulators covered those vertical walls on the attic side to prevent heat loss into the attic.  They used R20 closed cell spray foam extreme home insulation for those walls AND R20 of the same foam over all the attic hatches. In the process the crew also sprayed the end vertical wall (above the SIP walls which was a 2X6 outside wall.

Outside Ducts and Inside Exhaust Duct

Extreme home insulation demanded that we use a Closed Cell high density spray foam where necessary.  This foam insulation protects the vertical wall between the house attic and the warm shop inside the vaulted ceiling.

Houses undergo a different set of extreme home insulation challenges.

At a different time the insulation crew tackled the house.  The insulators had to use the same spray foam to full cover a myriad of openings that lose heat.  For example they had to cover all the following (plus more):

  • All the ceiling seams
  • Outside electrical outlets
  • electrical boxes for light fixtures
  • Wires coming through equipment room ceiling
  • Any other kind of holes through the ceiling into the warm home area

I placed a five gallon paint bucket over the top of all the recessed light fixtures in the kitchen area.  Then the sprayer covered the bukets with spray foam as well.  We purchased LED lights for all the recess can fixtures back when they were still expensive.  That purchase enabled us to use high lumen light bulbs with very low power dissipation.  Incandescent bulbs present a hazard in super well insulated can fixtures.

We had a good reason for using the foam insulation to plug any holes we could find that led from the inside of the house into the outside air.  Any open holes allow fenestration of air that can get through blown-in insulation.  When we block those holes it sets up a dead air space throughout the loose insulation that is applied later.   Energy is greatly reduced with the combination of blown-in insulation and totally dead air in between the insulation fibers.

Extreme home insulation gets a boost from Energy Heel Trusses.

Energy Heel Trusses support the entire roof over the entire building.   These trusses create more space above the top of the SIP wall plates than  trusses without this feature.  That space allows more foam insulation to fit under the trusses and OSB roofing. That resulting space extends along the entire perimeter of the building over the top plates.  The crew sprayed several inches of foam insulation over the SIP walls.  The foam even extends up under the cardboard soffit baffles.  The soffit baffles allow cold outside soffit air to rise next to the pitched roof and above the blown in cellulose insulation.  We covered the entire attic space with R60 blow-in insulation to meet our extreme home insulation goal.    The foam and blow-in insulation stops all cold air from coming in close proximity to the ceiling below.

We will dedicate a future blog to blower door tests, but first, I will throw out a teaser.  I will explain what we did without giving you the results until you receive the blog.

A regional blower door test agent performed such a test on our house before the blow-in insulation.  We hoped we found and foam insulated all the holes between the attic and the heated house space below, but you never know until testing is done.  A blower door test was performed before we added R 60 worth of blow-in cellulose insulation throughout the building.  That way we could still foam over any air leaks we might find in the blower door testing process.  Fortunately, we only found a few places we had missed!  I will present some of the test results in the future blog.


I consider extreme home insulation to be the very foundation of making a true Net Zero energy home.  That can be especially true in Montana.  You will require vastly more energy to keep your house heated and cooled without good insulation.  I need to add a special note after making the previous comments.  Active PV solar panels have become much more affordable since we finished our home building project.  Therefore, if you pursue a Net Zero energy goal, be sure to weigh the costs of adding super insulation.  The insulation route might just cost more than simply adding to or starting a new active solar system. Some comparisons might surprise you!  Good luck in whatever extreme home insulation endeavors you may take!  Mike