Cellulose insulation comes compressed and packaged in jumbo blocks. The cellulose is broken up into loose material during the blowing process.
In the last post I spoke about the process of insulating the roof. We opted to install the insulation ourselves, even though many people prefer to hire a contractor for a specialized task such as this.
One problem that faces the do-it-yourselfer is the seemingly endless number of decisions which have to be made during construction—when you build your own home, you are faced with many choices, both practical and aesthetic, every day. With the construction of a conventional house, you can usually get a lot of helpful input from contractors so you can make informed choices, but with green building, contractors may actually have less knowledge in this area than you do. Finding green-friendly sub-contractors can take quite a bit of research. If you cannot find a sub-contractor who is experienced with green design, the alternative is to hire someone with less experience and expertise in green building, and to to be as educated as possible yourself so as to steer him in the right direction when the need arises.
Many years ago, before I built my own house, I was involved with the construction of another adobe home. The plumber on this project felt that insulating hot water pipes was a waste of time. Now, twelve years after the house was built, I still think of this plumber every time I visit the place— because every time I turn on the kitchen faucet to get a drink, warm water comes out of the cold water tap. Not only is the circulation system on the hot water line losing a tremendous amount of heat to the surrounding area, the heat is also transferring over to the cold water line, since the two pipes run side by side. I'm sure that a mistake like this is not how the plumber would like to be remembered. For me, though, the incident served as a valuable lesson: one must make sure that potential problems like this, even small ones, are properly dealt with as they arise during the construction phase.
Make sure that all of your pipes are properly insulated, both to prevent heat loss in the hot water lines and to insure that the pipes will not freeze when exposed to cold air in the winter. Also make sure that the proper freeze-proof hose bibs are used on the outside wall of the structure.
Just as with plumbing, it is vitally important that the insulation of the house be installed correctly, particularly when batt insulation materials such as cotton or fiberglass are used. Although fiberglass would be discouraged in a green home (mainly due to the high amount of energy that is required to manufacture it and the fact that some of the binders in the material are toxic), it is still a very common insulator and must be carefully installed. Batt insulation needs to be installed without gaps between the rafters, wall studs, pipes or vents. Without a tight seal, energy efficiency will drop dramatically. This is why blown-in insulation may be preferred as its very nature is to seal up all these potential gaps in hard-to-reach places.
My home does not have any exterior adobe walls—they are all straw bale. However, if you do plan to have exterior adobe walls, it is important to note that certain local building codes may require that the exterior sides of these walls be insulated. This is the case in this part of New Mexico. The exterior insulation slows the transmission of heat through the wall, and, when properly insulated, the thermal mass of the wall also works to stabilize indoor temperatures. Builders often opt to use a spray-on foam insulation for this purpose. When using this type of product, avoid extruded polystyrene as it contains a blowing agent that is damaging to the ozone layer, as well as chemicals which are considered hazardous.
For many companies and individual contractors, quality workmanship is what made them successful in the first place, so they will make every effort to do a good job for you. For others, however, your project is just another job, and they want to get it done as quickly as possible, because time is money. So it is up to you to make an informed choice when hiring someone to help you build your home. Because it is you—not the plumber or the electrician or any other sub-contractor—who will be living in the house for years to come.
More next time on building a green home.
[This has been a guest post by Ted Owens, a green designer and filmmaker. More details on green building design and construction can be found on his website and in the Building with Awareness DVD and Guidebook. -Ed.]