Here are four possible reasons for gaps in your attic insulation:

1) Insulation was moved for repair or installation work in attic and not replaced afterwards - Workmen in the attic have to move it for repairs or new installations of cable, plumbing, or electric. Sometimes they do a sloppy job of putting the insulation back, or don’t bother at all.

2) Critters - Rats, squirrels, or birds that find their way into an attic move insulation around as part of their nest-building process. Fecal pellets and shredded insulation in the area are a clue that’s the problem.

3) Remodeling of porch, carport or garage into living space - Rooms that are not used as a living space are not required by the building code to be insulated at the time of original construction of a home. Sometimes the addition of insulation above the ceiling is not done when they are converted to interior living areas. We often see this problem in a garage remodeling. This can be because of a simple oversight by a weekend-warrior remodeler or due to lack of easy access to the area between ceiling and roof. 

4) Insulation poorly secured - Insulation on vertical surfaces in an attic, such as around the light shaft for a skylight, or the walls of rooms built into an attic, can slide down the wall over time if not well secured.

    And, on just one occasion, we inspected a new house where the builder just forgot to install the attic insulation. Gaps in attic insulation are easily detected from below the ceiling by any home inspector with an infrared camera, and noted with photo documentation in their report.

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Here’s links to some of our other articles about ATTIC INSULATION: 

• What are the common problems with attic insulation?

• Why is vermiculite attic insulation a problem for both buyers and sellers of a home? 

• Why is the garage so hot in the summer?

• How can I tell if a house has insulation? 

• Why is spray foam used for attic insulation? 

• Should I put some more insulation in the attic?

• What does the "R-Value" of home insulation mean? 

• Is cellulose insulation flammable? 

• What does the U-value of insulation mean?  

• Does code require water pipes in the attic to be insulated? 

• Does a home inspector check insulation? 

• Does the code require a barrier/well around the attic access hatch for blown insulation?

• How long does fiberglass attic insulation last?