How to Seal Attic Air Leaks

Faced insulation refers to insulation material that has a vapor-retardant or vapor barrier attached to one side. This facing, often made of paper or foil, helps control moisture by preventing the movement of water vapor through the insulation.

Go with faced insulation if you’re insulating the attic’s floor joists. Either option is suitable for rafters without insulation or where attic insulation has been removed. But, if you’re adding new insulation over existing insulation, the new insulation should be unfaced to avoid trapping moisture between the layers.

Read More: Can I Add New Insulation Over Old?

Homeowners have multiple options for installing new attic insulation over existing. These include:

• Adding rolls of insulation to an under-insulated space (make sure the rolls are unfaced)
• Laying unfaced batts perpendicular to the joists on top of the existing insulation
• Blowing insulation into the floors and walls

The goal of upgrading existing insulation is to enhance the R-value, also known as thermal resistance. In cool, dry Colorado, attic insulation needs to be R-49. Adding layers of insulation is an effective way to seal the attic.

Absolutely! Fiberglass rolls are the most common choice for insulating the attic when a home is being built. Over time, it may be necessary to upgrade the attic insulation roll.

Fiberglass insulation can be retrofitted with new fiberglass rolls. Other types of rolled insulation (such as mineral wool or cellulose) can also be added to complement the existing fiberglass.

Retrofit insulation needs to be measured and cut precisely to ensure the new insulation fits the space and provides the necessary R-value. It is generally best to have a professional insulation contractor handle the job.

Batt insulation is another fine choice for sealing attic leaks. New batts (made from fiberglass, cellulose, mineral wool, etc.) can be laid across old batts if they are in good condition and there is no excess moisture present.

One of the advantages of batt insulation over rolls is the ability to retrofit or replace smaller sections. Some cutting may be required to fit the batts in place.

Retrofitting attic insulation can also be accomplished with blown-in insulation. The process consists of simply filling the space with enough insulation to achieve the desired R-value.

Blown-in insulation can be added to the walls, floor joists, and baffles of your attic. Although you can rent a blown insulation machine and handle the install yourself, insulation professionals can determine how much is needed to fill the space and provide adequate thermal resistance.

Loose-fill material isn’t as thick as batts, rolls, and other types of insulation. This can make it difficult for homeowners to know how much blown-in insulation they should be using in the attic.

While having too little attic insulation is the more common problem, it is possible to over-insulate the attic if you’re not careful. In addition to wasting money on materials, excess insulation can lead to problems such as mold and mildew if moisture becomes trapped in the layers—particularly if the attic is unvented.

Read More: Is There Such a Thing as Too Much Insulation?

Sealing attic leaks is important, no doubt about it. But we also want the space (and, by extension, the entire house) to be properly regulated.

Experienced home insulation contractors can determine how to seal attic air leaks. First, they will perform a complete assessment of the attic space, including the quality and quantity of the insulation. Next, they can recommend upgrades. Insulation removal may be necessary in extreme cases, but we generally find that existing insulation can be upgraded to seal the attic effectively.