Fiberglass Batt Insulation
The most common form of attic insulation material and one that you are likely already familiar with is fiberglass batt insulation. The rolls of material, cut in compact lengths, line the joists of your ceiling to cover a very large majority of any leaks. This type of insulation is very economical and covers a lot of area very quickly. It does however, leave a few spots open so it's best to have another form of insulation compliment the fiberglass batting, such as loose fill.
Spray Foam Insulation
Spray foam insulation for your attic, besides being very effective, has one major benefit over other forms of insulation. The spray covers all the tiny holes that is naturally in all forms of lumber which eliminates any moisture coming into the home from the exterior, and ensures that all the energy within the home stays put. Because of this, most spray foam insulation is used primarily with exterior walls, but can be used just about anywhere in a home. Spray foam insulation is installed by having a machine outside the home, hold different chemicals separately until they get to the nozzle. When the contractor starts spraying, the chemicals mix and instantly creating an expanding foam. The foam will conform to the space it was sprayed in and it will expand 2-4" in one pass, so a few passes may be needed depending on the depth of the wall.
Loose Fill Cellulose
The other type of attic insulation material common in the market is loose fill, or blown-in, made from cellulose or from fiberglass. This type of insulation is mainly used in the attic due to the fact that it doesn't conform to a vertical or above space. The insulation is more like the "fluff" inside a pillow.
The reason why loose fill is also called blown-in is because of it's applied. The insulation itself comes in compacted blocks and a machine breaks up these blocks and "blows" the insulation through a hose. The contractor applying the insulation will start in one corner of the attic, fill it to a couple of inches above the joists and continue on. A lot of insulation is used in this process, and it does take a little bit of time to complete, but loose fill is extremely economical and gets the job done quickly and efficiently.
Ideally, using all three forms of insulation is going to get you the best results. But using all three in one location probably wouldn't be a good idea as the house does need to breath a little bit. Obviously the person who will get the best answer for your home will be a home contractor. They can look at how old your home is, what the structure is like and, a more a concerning reason to hire a contractor, they'll know what the current building codes are.
