The thicker the better.
How thick should insulation be in an attic.
They range from around 1 to 3 inches in thickness and can be used in multiple applications ranging from walls to attics.
The insulation in your attic should be at least 12 thick.
Inspecting your attic insulation.
First things first you need to go up into your attic inspect the condition of the insulation and calculate the current level of insulation.
Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation.
So if the ideal r value for your home is r 40 your contractor may only need to spray five inches of foam insulation.
In temperate coastal areas such as zone 3 attic insulation of at least r30 up to a maximum of r60 is recommended.
The most common form that insulation comes in is a batt or blanket these are large rolls of insulation that are easy to cut into usable shapes.
The recommended level for most attics is to insulate to r 38 or about 10 to 14 inches depending on insulation type.
It is not uncommon to see 15 to 20 of insulation in a well insulated attic.
For loose fill cellulose this translates to a total depth ranging from 8 inches.
This is compared to having to stack fiberglass as high as 14 16 inches to get the same results.