Attic crawlspace closets, foundation crawlspaces, and unfinished basements are large areas for energy loss. These areas are hardly ever insulated correctly and are not that easy to insulate to begin with. Or are they? One of the biggest problems with the movement towards energy efficiency is that people do not understand the thermal principles of a home and how to best conform with those principles for maximum energy efficiency, in terms of heating and cooling. By creating a blanket of insulation that does not allow penetration even through the framing, home can operated at a significantly lower energy cost and the easiest place to do this is in unfinished spaces that are going to remain that way.
Creating A Monolithic Thermal Blanket
Monolithic is another way to say continuous, so a monolithic thermal blanket is simply a continuously insulated surface. I am going to lay out a few examples for you on areas of your home that you can insulate in a monolithic way. All of these methods will incorporate using closed cell spray foam insulation:
If you have a closet area in an attic crawlspace that you use for storage, you can insulate this area completely by bringing it into conditioned space. In other words, insulate the underside of the roof. Start where the roof meets the floor. Spray over the top plate of the wall and into the cavities, making sure to spray along the edges of the roof rafters before filling the interior of the cavity. This is called picture framing. You will need about 3 inches but no more than 5 to be affective in insulating this space. This requires about 2 or 3 separate sprays on the surface of the cavities. Once you have insulated this area, spray a layer of foam on the roof rafters themselves, completely encapsulating them. Make sure it ties into the insulation in the rafters. You now have one large insulated surface with no framing that will lose energy through it as it is part of the insulation system.
Lay 6 mil plastic down on the ground and run the plastic about 12 inches up the walls. Spray a layer of spray foam about 1 1/2 inches thick on the walls. You will spray onto the plastic that is ran up the wall also making sure that the plastic is tight against the wall when spraying. This seals the plastic to the wall and prevents any moisture from escaping into the crawlspace.
Spray the box sill areas with spray foam wrapping the foam down on top of the foundation and onto the wall insulation. Once again, you have formed a monolithic thermal blanket that encompasses the entire crawlspace.
Spraying the basement walls is just like spraying the crawlspace walls, except you will not need to wrap plastic on the floor as no vapor barrier is needed, and you will need to coat the surface with a fire coating. There are several types of paints that meet fire retardency standards.
Creating a monolithic thermal blanket makes the most sense when insulating unfinished spaces and reaps the largest energy savings rewards.