In temperate coastal areas such as zone 3 attic insulation of at least r30 up to a maximum of r60 is recommended.
How thick should insulation be in an attic.
The thicker the better.
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.
Add the right kind of insulation when adding additional insulation you do not have to use the same type of insulation that currently exists in your attic.
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.
So if the ideal r value for your home is r 40 your contractor may only need to spray five inches of foam 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.
They range from around 1 to 3 inches in thickness and can be used in multiple applications ranging from walls to attics.
This is compared to having to stack fiberglass as high as 14 16 inches to get the same results.
Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation.
Find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces.
The recommended level for most attics is to insulate to r 38 or about 10 to 14 inches depending on insulation type.