When adding insulation to my home, do I need to remove the old insulation?

Adding more insulation can be a cost-efficient way of improving the indoor environment of your home and lowering utility bills. But is it ok to install new insulation on top of old insulation, or should you remove the old insulation first?

The answer depends on a few factors, including the condition and volume of the existing insulation. This article will discuss how to assess the relevant factors, whether the type of existing insulation makes a difference, and finally, a few important things to note when you want to properly add new insulation on top of old insulation.

Consider the Condition of Insulation

An inspection of your existing insulation should be performed before new insulation is installed. If the existing insulation is moldy, wet, or has evidence of pest infestation, it should be removed and replaced. It is also necessary to identify the cause of any moisture or pest problems and fix it before proceeding. If your insulation appears to have previously been wet but is now dry, you should likewise identify and resolve the cause of the problem.

Check the Existing Levels of Insulation

According to the Environmental Protection Agency (EPA), the attic is the most cost-effective area of the home to add insulation and improve comfort and energy savings. You can check the depth of your attic insulation to see if more should be added.

A simple assessment that can be performed regardless of the type of insulation material present is to just look across the span of the attic. When insulation is at the same level or below the floor joists (in other words, the joists are easily seen), more insulation can likely be added on top. If it is difficult to see the joists because of the insulation material’s depth, then you probably already have enough insulation.

R-value is a measure of how well a certain type of material insulates. The recommended R-value for most attics is R-38 (10-14 inches depending on the type of insulation). To determine the current R-value of your attic and the proposed R-value of any additional insulation, add up the stated value (on the product label or in the manufacturers information) for each layer you have or plan to add.

Does the Type of Material Matter When Adding Insulation?

When additional insulation is being installed, it is usually not necessary to use the same kind of insulation that is already in place. Loose fill or blown-in insulation can be used on top or under fiberglass batts or blankets. However, if you are adding a batt-type insulation on top of existing insulation, be sure the batts you add are unfaced (without a vapor retarder). This will help you avoid moisture, mold, or rotting issues.

If you will be adding spray foam inside walls or to the attic, it may be necessary to remove existing insulation first. Additionally, if you discover vermiculite insulation, removal may be necessary.

Vermiculite insulation looks like gray-brown or silver-gold pebbles and is pour-in product that can be used in attics or walls. If you have vermiculite insulation in your home, the EPA recommends assuming this material may be contaminated with asbestos. This means the homeowner / DIYer will leave vermiculite insulation totally undisturbed and have a trained professional test it for asbestos before installing more insulation. If removal is deemed appropriate, it should be handled by a trained and accredited asbestos
abatement contractor.

Important Notes When Adding New Insulation on Top of Old Insulation

When adding new insulation on top of old insulation, there are a few more things to consider:

The EPA states that attic air sealing should be performed before adding more attic insulation. Eliminating air leaks can pay off big by increasing your home’s efficiency, durability, comfort, and indoor air quality. When combined with proper attic insulation, it can also keep dangerous ice dams from forming in the
winter.

When installing new rolled insulation on top of old insulation, it should be rolled out perpendicular to the joists. And as already mentioned, be sure to use unfaced products to avoid moisture problems.

Adding Insulation Pays Off

When you have added new insulation properly, the results can mean great savings, a lighter carbon footprint, and multiple benefits to your family. Your home will be more comfortable, use less energy, safeguard your indoor air quality, and cost less to maintain. It is a project that is likely well worth the effort.

Don’t wait any longer to improve your home’s energy efficiency and comfort. Contact us today to schedule your insulation removal and installation.