Should I Add New Insulation to Old Insulation?

At Insulation Hamilton we get a lot of reoccurring questions about insulation removal.

If you’re considering adding new insulation to your attic, one of the first questions is whether you should remove the existing insulation.

Here’s a few things to consider before making a choice:

Historical Background

Attic insulation has been used for generations to help manage the temperature inside dwellings (To learn more about attic insulation check out The Ultimate Guide to Attic Insulation).

People used to insulate their attics with wool, straw, or newspapers.

The insulation business has produced many new types of insulation over time, including fiberglass, cellulose, and spray foam (To learn more about spray foam insulation check out The Ultimate Guide to Spray Foam Insulation).

Today’s Insulation

Modern insulation materials are designed to be more effective at preventing heat transfer than earlier ones.

Fiberglass insulation, for example, is formed of tiny glass fibers that trap pockets of air to limit heat transfer.

In contrast, cellulose insulation comprises recycled paper treated with fire-retardant chemicals.

While current insulation materials are more effective than earlier materials, this only sometimes implies that existing insulation should be removed before adding new insulation.

Many expert insulation companies actually do advise leaving old insulation in place and installing new insulation on top, especially if budget needs to be maintained.

Consider the Following Factors

Numerous considerations must be considered when selecting whether or not to remove existing attic insulation before installing new insulation. Here are a few of the most important:

Old Insulation Condition

The state of the original insulation is one of the most significant variables to examine.

Before installing new insulation, the old insulation should be removed if it is damaged, polluted with mold or mildew, or infested with vermin.

However, in good shape, old insulation can typically be retained in place.

Adding new insulation on top of old insulation can increase the attic’s overall insulating value.

Old Insulation Type

Another critical element to consider is the sort of old insulation you have. If the existing insulation contains dangerous elements such as asbestos, it should be professionally removed before new insulation is put in.

If the old insulation is composed of a non-hazardous substance, such as fiberglass or cellulose, it can frequently be left in place and covered with new insulation.

Old Insulation R-Value

Insulation’s R-value is a measure of its resistance to heat transmission.

The greater the R-value, the better the insulation at preventing heat transfer.

If your attic’s original insulation has a low R-value, putting new insulation on top of it can efficiently boost your attic’s total insulation value.

Home’s Age

Another significant element to consider is the age of your home. If your property is relatively recent, the attic insulation may be in good shape and not need removal.

However, if your property is older, the insulation may be decaying and must be removed before new insulation can be placed.

Your Local Climate

Another significant element to consider is the climate in your area.

Canadian winters can be tough if your home isn’t insulated properly. By putting new insulation on top of old insulation can effectively boost your attic’s insulating value.

However, if you’re concerned about the Southern Ontario summer heat, installing new insulation on top of old insulation may be ineffective since it might trap heat in your attic and make your home less pleasant.


To summarize, whether or not you should remove old attic insulation before installing new insulation is determined by many criteria, including the state of the old insulation, the type of old insulation, the R-value of the old insulation, the age of your property, and the climate in your area.

Connect with us today and we will be able to give you a more thorough answer regarding your own unique situation for insulation removal and installation.

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