Batt insulation is still the most common type used in home building. Why? It is the least expensive. Batts are typically made of fiberglass. There are some suppliers that offer natural batt products such as wool or cotton. This can be an important option for some owner builders.
While you can get a well insulated home using fiberglass batts, it requires that you pay special attention to installation. Look for gaps, voids and compression. Be particularly aware of problems that can occur around fixtures, pipes, outlets and other items that could cause air gaps in your wall.
The advantage of blown cellulose over batts is that those gaps and voids that the owner builder worries about with fiberglass batts, almost disappear. Installers "blow in" a loose fill of cellulose(treated recycled newspaper ) or fiberglass. There is typically a light adhesive and the mixture is slightly wet so it sticks inside the wall cavity. Shears are then used to cut the material flush with wall studs.
If blow in cellulose is used on interior walls for sound, netting is stapled in place and the wall cavities a filled dry.
Blown in products are more expensive than batts but the gap is closing. Cellulose is slowly becoming the industry standard. It's worth the extra to insure a tight home. For more information about blown cellulose insulation, including a video, click here.
While batts and blown in cellulose or fiberglass are the big 3 products used for residential construction, other products are making headway.
SIP's( Structural Insulated Panels), are just what they say, they insulate AND they're structural. An SIP is basically a premanufactured wall member that consists of a foam core sandwiched between two pieces of OSB(Oriented Strand Board). Whole home kits of SIP's can be purchased. If a framing crew is experienced with the product a building can go up very quickly. Because of their design, the owner builder gets a very, very tight home.
It is important to research carefully if this is a direction you wish to go. There are a lot of options and as always, quality varies.
Spray Foam Insulation
Spray foam insulation is another amazing product that not only insulates, it seals. It is applied in the wall with a sprayer and it expands and fills the entire cavity. Shears are used, as with blown in cellulose, to flush up the insulation with framing members. Because of it's sticky properties it can be applied to the attic roof. This creates a conditioned space for your ductwork, reducing the impact of heat.
This is an inspection that can go either way. Often, an old timer will come in and just breeze through your inspection. In the past, insulation was merely an afterthought. I have also had inspectors that fail the house for a quarter inch gap in at the top of a single wall cavity. That is what you want when you are building your own home. You should make sure it happens whether the building inspector does or not.
After your inspection is complete, drywall hangers can start.