Because of how much energy and money is spent on heating and cooling, insulation is one of the first places to look to save energy. Insulation allows you to avoid heating and cooling losses by installing a thermal barrier. Insulation is used to keep your house warm in the winter and cool in the summer by limiting air movement within the space it occupies.
Insulation performance is measured in “R-Value,” which is a rating on the materials’ ability to resist heat. The higher the R-Value, the greater its insulating power. Recommended R-Values differ for walls, attics and basements, as well as the region you live in.
Insulation comes in a variety of sizes, shapes and materials to suit a variety of different needs.
Blanket, batt or roll insulation comes in flexible pieces made from mineral fibers such as fiberglass or rock wool. Each is available in widths designed to fit standard wall stud, attic or floor joist spacing. Installers have to hand cut the batts to fit special areas such as around windows. This type of insulation is also available with both flame and vapor-retardant facings.
Blown-in loose-fill insulation comes in the form of loose fiber or pellets that are blown in with pneumatic equipment, generally by professionals. Loose-fill insulation can be made from cellulose, fiberglass or rock wool and is appropriate for wall cavities, unfinished attic floors and irregular shaped spaces/obstructions.
Foam insulation is also usually applied by professionals. This type of insulation uses mixing equipment to meter, mix and spray the foam into place. There are 3 different types of foam insulation available - Polyicynene, polyisocyanurate and polyurethane. Polyicynene is an open-celled foam, which allows water vapor to move through the material easily. Polyicynene and polyisocyanurate are closed-celled foams, which do not allow water vapor to move easily through them. Closed-cell foams usually have a higher R-value when compared to open-cell foams, making them more appropriate for areas with limited space.
Rigid Insulation is produced in board form and molded pipe coverings, generally from fibrous materials or plastic foams. They provide full coverage and do not allow for many heat loss paths, meaning they provide greater R-Value in limited spaces. This type of insulation can be faced with reflective foils to reduce heat flow when adjacent to an air space. The most common use for rigid insulation is for foundations and wall sheathing.
Reflective insulation systems are made out of aluminum foils and have a variety of different backings such as kraft paper, plastic film, polyethylene bubbles or even cardboard. Reflective insulation systems are best used to reduce the downward flow of heat and are typically found in roof rafters, floor joists and wall studs.
As mentioned above, insulation can be made from a variety of different materials, including fiberglass, rock/mineral wool, cellulose, polystyrene, polyurethane/polyisocyanurete and air crete, just to name a few.
Fiberglass is made into blankets, batts or rolls by spinning glass fiber together using a glue, followed by attaching a vapor barrier backing. In this form, fiberglass is a good insulators with R-Values between 3 and 3.5 for every inch installed, but does have the downside of losing its insulation ability in extreme cold weather and can break down over time with age. Glueless fiberglass is also available.
Rock/Mineral Wool is a fiber made from various rock and mineral byproducts possessing similar characteristics to fiberglass. Although quite common in the 1940s and 1950s, this type of insulation is no longer a popular choice.
Cellulose is a 100% biodegradable type of insulation that bears similar R-Values to fiberglass, but is made from recycled newspaper and immersed in a borate solution to boost its fire and insect resistance. It can either be blown in dry, or sprayed on wet. However, if it comes in contact with moisture, the borates may be extracted and leave the insulation vulnerable.
Polystyrene is better known as Styrofoam, is a petroleum based insulation that is blown with a gas and formed into boards. Gases used in the past have been known to contact CFC or HCFC materials, meaning they were bad for the environment and led to ozone depletion. However, manufacturers have recently switched to Pentane or Carbon Dioxide gas as an alternative, which is more environmentally friendly. Styrofoam is a marginally better insulator with an R-Value of 4 per inch, but is flammable and may leak gas over time, reducing its insulator properties.
Polyurethane and polyisocyanurate are plastics blown with gas, but promise higher R-Values than polystyrene, as much as R7.5 per inch in the case of Polyisocyanurate. Polyurethane is marketed as also being more environmentally friendly foam and is featured in many healthy demonstration homes.
Air crete is a unique cement product with air contained within that is installed as a foam. Its R-Value is similar to fiberglass, but because it is a cement product, it does not have problems with silicosis. This type of insulation requires a lot of energy to produce it and even though it is recyclable, there is not a strong market for it.