As you know we are focusing our budget on the major guts of the home that are not easy to upgrade in the future. Probably the biggest organ of all in the home is the insulation or quality of the shell. I can’t believe all of the home improvement shows I have seen lately that are focusing on replacing the insulation in not so old homes to bring them up to their homeowners new green standards. It’s painful to watch and looks quite expensive. We don’t want that happening to our home buyers so we are committed to building the most cost-effective, efficiently insulated home possible.
These are not all of the options out there for insulation, but they cover the main options that you can use for a nicely sealed home that we are considering.
Traditional Batt Insulation or Alternatives
Batt or Blanket Iinsulation is the most common and least effective insulation used in the states today. It has an approximate rating of R-3 per inch. Technically the R rating is even lower because typical batts are so loose that they allow air to penetrate them and cool them down. For example, 6.5″ thick R-19 batts have actually been tested to achieve only an R-13.8 rating in typical installations.
Other issues with typical fiberglass insulation include difficulty of having it installed improperly and contributing to poor indoor air quality of the finished home. It is possible to use batts effectively in energy efficient homes but the installation is labor intensive. Since batts do not seal air out well, all joints and gaps must be sealed by hand and the batts must be precisely cut to fill all gaps perfectly, especially around electrical outlets and gas or plumbing runs.
One slightly greener alternative to batts would be to use batts or rolls made of natural fibers such as Bonded Logic’s insulation made from recycled denim jeans. These types of insulation typically have a slightly higher R rating and do not harm the indoor air quality since they are made of natural materials. The trade off is that they are pricey and still do not effectively seal air gaps without extra labor and supervision.
Blown-In Cellulose Insulation
Loose-Fill Insulation is an option that can be eco-friendly. Specifically, Cellulose is a type of blown-in or loose-fill insulation that is made from recycled newspapers. There pros and cons but the bottom line is that it will not provide much better R factors than batt insulation and typically will cost more to have installed. The best applications seem to be for attics that are not well insulated because cellulose can be quickly and efficiently blow over an attic floor to dramatically and safely increase the insulation between the home and the hot attic space.
Rigid Board Insulation
Rigid Board Insulation can contain some of the highest R values with some Polyurethane sheets reaching R-8 per inch. Since the insulation comes in the form of rigid boards it is popular as roof and wall coverings attached to the exterior of the framing of a new home. Attaching to the exterior of the framing will improve the strength of the structure while also creating an insulated break (thermal barrier) between the wood studs and the exterior sheathing or siding. This can greatly reduce the heat loss transferred from the inside of the home though the wood studs and to the exterior that occurs in the vast majority of new homes today in the U.S.
There are also green versions of rigid board that are normally classified as polystyrene rigid insulation. This type may contain some recycled materials and will not off-gas like some of the other sheet products might.
One last advantage to rigid board insulation is that you can find boards that are laminated or strengthened to act as both the homes sheathing and insulation. Since sheathing of some type is necessary, this doesn’t eliminate a step but can greatly improve the building envelope without additional labor.
Spray Foam Insultion
Spray-Foam Insulation is probably the most effective type of insulation for traditional, stick-framed homes available today. The product is in the form of a liquid that is sprayed on and quickly expands to 100 times its size. It can achieve R values of R-9 per inch but most importantly, it automatically creates an almost perfect air seal upon expanding. While the product is costly, it is effective and reduces a lot of manual caulking and sealing that would be necessary with other types of insulations.
The most popular forms are petroleum based but there are also green options such as BioBased Insulation that is composed of 96% bio-content (soy-beans).
SIPs or ICFs
SIPs or Structurally Insulated Panels are arguably the best way to achieve a tightly sealed and well insulated home. They are basically two sheets of OSB with spray foam insulation sandwiched between them. They are both structural as well as insulating so they eliminate the need for traditional framing and can streamline the construction of a home is assembled properly. All seams are sealed and there is no thermal bridge from studs. The only downfall is many contractors are unfamiliar with them and they can be quite pricey.
Many green builders are using SIPs today and are vehemently opposed to stick building as they view it an obsolete building practice.
So this is all great info but what are we leaning towards? Well, as I see it here are our top 3 options:
- Rigid Foam Board on exterior of framing with Spray Foam Insulation sprayed inside of 2×6 on 24″ center framing.
- Nothing – I don’t like the other alternatives and will not pursue unless we really can’t afford 1 & 2.
Types of Insulation – U.S. Department of Energy (Great Table with comparisons and links)
If you enjoyed reading this post I can promise you'll love our new writing over at Postgreen Homes. Yeah, we know that's the same thing your favorite band said and their new album is nowhere near as good as their early stuff, but seriously, we are actually still getting better.
There also isn't much conversation to be had here . . . at least not with us. So come on over to the Postgreen Homes Blog and tell us what you think of our new(ish) digs and crazy ideas. We will be sure to tell you what we think of your opinion.