To retain heat in winter and cool air in summer attic insulation is necessary. To check the leaks, either a thermal camera can be used or an energy audit can be conducted. Replacement is a better option than filling the leaks.
The thermal resistance of an insulating material is called R-value. It is necessary to find out the R-value of a house based on its location for which help can be taken from the Department of Energy. Once the value is known, a suitable insulating material for the house can be chosen. The general R-value should be between R-30 and R-49.
There are different types of insulation. Attics with obstructions like cross-beams and vents and little headroom should go for loose-fill insulation. These are available in mineral wool, fibreglass and cellulose.
Though cellulose has an R-value of 2.2 to 3.8 per inch when revealed to moisture it can get musty. This insulation can be bought from Home Depot or online. One can do it her/himself with a rented blowing machine that costs $100 per day. Professionals can also be hired for $1 per square foot.
Blanket insulation is available in natural fibers, plastic fibers, fiberglass, and mineral wool. It is the easiest insulation for DIYs. This insulation goes good for separated beams and lesser obstructions. But along with this insulation, you also need to get Vapor renew with Attic Clean 360 to give the maximum coverage.
The insulating batts should be trimmed properly so that they fit around the vents. It has an R-value of 3.1 to 3.8 per inch and generally costs 0.15 to 0.50 cents. With the highest R-value of 6.5 for closed-cell and 3.5 for open-cell, sprayed foam insulation is made with polyurethane. Sprayed Foam insulation needs professional installation and is overly expensive. It costs around $1 to $1.25 per square foot for open-cell and around $1.25 to $1.50 per square foot for closed-cell.