Insulating a loft properly with fiberglass can lead to savings in the money spent on heating a house. This is because a poorly insulated roof can lead to heat seeping out. Effective loft insulation alone can lead to a 20% savings on energy bills. A good insulation will help in keeping the house warmer during winter and cooler during summer.
The common constituents of fiberglass batts include soda ash, ground sand, and boron. Fiberglass acts as a good insulator because it has a number of trapped air spaces or cells. Air does not move out of these cells and thus helps in preventing heat loss. Fiberglass also acts as an acoustic insulator. This is because a fiberglass batt has a number of anechoic chambers that reflects sound inwards from a number of diverse surfaces. Another benefit of fiberglass is its non-corrosive nature. Fiberglass has no effect on the corrosion of steel or aluminum and can be applied directly on sheet metal.
The insulating capacity or the R-value of fiberglass varies a great deal. A high R-value for fiberglass would be R38. Size of fiberglass batts vary depending upon the area that the insulation needs to cover. A wall having 2" X 4" wall stud will require a fiberglass batt that has a thickness of 3 ½ inches. Insulation that is thicker will need to be compressed to fit into the space and this is not ideal. When fiberglass batts are compressed, they tend to lose their R-value.
The ideal way to install fiberglass insulation is from within the house and placing it against the sheathing. This fiberglass should be covered on the outside with an air barrier and an exterior siding. If insulating the attic, the insulation should be laid flat between ceiling joints. Some fiberglass batts come with a paper facing that acts as a vapor barrier. Vapor barriers are essential to prevent the flow of moisture and air through the insulation. They also come with an edging which ensure that stapling the batt in place is easy. If the batts are stapled incorrectly, then there could be small channels of air which pass through it and reduce the R value. This also goes on to present fire safety issues.
One disadvantage of using fiberglass is that is has lower resistance to fire as compared to other insulating materials. Another disadvantage of using fiberglass is that its R value reduces significantly once the insulation becomes wet. Care should be taken when handling fiberglass batts as fiberglass is made up of small particles that can affect your skin and respiratory tract. Protective measures such as the use of facemasks should be undertaken when installing fiberglass.