• Mark Gordos

Why Does Existing Insulation Need to be Removed

We often get asked why existing insulation needs to be removed. There are two answers depending on the type of insulation being installed.


When blow-in fiberglass or cellulose insulation is being installed, extraction of the existing insulation is not always required. In many situations, the existing insulation can remain in place and new blow-in or batting can be installed on top. In Florida, building code now requires an R38 value which is achieved either by thirteen inches of loose fiberglass or cellulose or batting with a combined value of R38.

So when do you need to remove existing insulation if blow-in or batts are being installed? The obvious answer is when the existing insulation is so old it has deteriorated or you have a pest or insect infiltration. Unfortunately, our attics attract vermin and they love to nest in blow-in and batting insulation. Before you have an insulation company, like On The Mark, come in to extract and install, a pest company should be hired to eradicate the pests. Finally old insulation is often a habitat for allergens and moisture retention. In Florida's humid climate, the integrity of blow-in and batting deteriorates within eight to ten years and each year the amount of allergens and moisture content increases.


The application of spray foam requires a clean surface to adhere to and existing insulation is in the way. In addition, since the purpose of spray foam is to create a sealed air envelope to result in your attic being a conditioned space, the removal of at least 70% of existing insulation is required.

Installing spray foam, while more expensive due to the cost of the material and the removal of existing insulation, is recommended. Spray foam does not deteriorate and the product has a lifetime warranty. Spray foam does not absorb moisture or attract pests because of the sealed air envelope. Removing the existing insulation ensures spray foam will work efficiently.

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