Insulation, 
Air Barriers and Air Sealing are not Over-Rated
by Don Ames
The plan was to visit the home and ask the homeowners what they would like to do first to fix up their home. I had about a 40 minute drive, took the old highway to avoid the rush of the freeway – stopped and grabbed a Mountain Dew on the way.
Older communities along major roads can sometimes present problems when it comes to finding an address. The road was not always a four lane road with a divider in the middle - it became apparent that my Internet map was going to be a little off. On my third trip around the block, by process of elimination, I zeroed in on the only driveway that made sense.
Before the freeway went through, this road was the main North and South route. Old, single story strip motels have been turned into really old apartments. The driveways here were never asphalted and trees were allowed to grow into buildings. I drove pass the purple colored motel to the small, muddy, 18 unit mobile home park in the back. The park consisted of mostly older, single wide homes. I have to guess which home is space #10, space numbers haven’t been repainted since steam locomotives ran along the adjacent railway tracks.
The inhabitants of space 10 are a very nice young couple expecting a baby in a month and they would like to fix the place up a bit to provide a better home for the new family member.
My inspection of the home presented a problem concerning repair and remodel, the home was simply not in good enough condition to fix up. The roof and walls had allowed so much penetration of rain water for so many years that the moisture damage and dry rot was everywhere. There would be no fixing up of this home, too far gone, both axels in the grave.
To keep out the winter rain until I could find a replacement home for them , I had a contractor cover the roof with a tarp.
The tarp, temporary air barrier;
Now, here’s the interesting part – several months later, I have joined the couple at a Title Company to sign papers on the used replacement home that will replace the home that is falling down around their ears. The couple thanked me for the tarp - saying the tarp not only kept the rain out, but also made the home much warmer.
Well, let’s think about this a minute. The tarp over the roof made the home noticeably warmer! The tarp would not have insulation value – just a thin piece of woven poly. The tarp would not have any heat production value from passive or direct solar energy. The tarp was not plugged into an outlet like an electric blanket. The tarps only value in warming the home would be the benefit of adding an air barrier to the roof. The tarp served the purpose of air sealing the roof. The warm air produced by space heaters in the home was not allowed to pass through the roof and heat the great outdoors.
What’s an air barrier?
An air barrier is the layer of a home that separates the outside air from the indoor air. A home needs to have an identifiable air barrier as part of all exterior walls, floors, and ceilings. An air barrier can be wood, siding, drywall, plastic membrane, asphalt paper, metal flashing, spray foam, underlayment, house wrap, weatherstripping, windows, doors and duct tape. Air barriers block random air movement through building cavities. Without an effective air barrier, the homes insulation can not do it’s job. In some cases, dense-packed cellulose in walls can be a partial air barrier. However, fiberglass insulation is never an air barrier, air passes almost freely through fiberglass.
It shouldn’t take an old manufactured home with a tarp over the roof to demonstrate to all homeowners about the importance of a homes air barrier. Air barriers and air sealing are not over-rated. When it comes to energy efficiency and warm, comfortable homes, identifying and maintaining the homes air barrier is paramount to an efficient home . Even new homes can have breaks in the air barrier that can be repaired and will result in power savings.
As a homeowner, you may not be able to have a do-it-yourself project and install a new high efficiency furnace or crawl under the floor for hours and seal and insulate your heating ducts. You may not be able to install your own double pane vinyl windows or replace that 20 year old water heater. But one thing you can do is research the location of your homes air barrier and start plugging the holes. Grab a strip of door seal, a tube of caulk or a can of spray foam, roll up your sleeves and save yourself some energy.
