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Adding New Insulation Over Old Layers

Do you need more insulation in your home? You probably already have insulation in your walls and attic, but maybe you’re wondering if you should remove your current insulation or add new layers over the old ones. So, can you install attic insulation on top of old insulation? Put simply, yes.

When considering new insulation installation or home retrofit insulation, many DC-area homeowners wonder if removing the old insulation first is necessary. Can you add new insulation on top? The answer, in many cases, is yes. You can often leave old insulation in place ― but not always. Here, we’ll explain the deciding factors, along with proper home insulation practices.

At Accurate Insulation, we’re experts in full-service insulation installation. Contact us for your free estimate, or keep reading to learn more about adding insulation to your Maryland home!

Get a Free Insulation Estimate from Accurate Insulation in Maryland!

Can I Add New Insulation Over Existing Layers?

According to ENERGY STAR®, you can put new insulation over old insulation, “unless it is wet. If it is wet or appears that the insulation has previously been wet, you should look for the cause and repair the problem…” Wet insulation is problematic, as it can lead to mold, mildew and sometimes the rotting of ceilings or roof rafters.

Although insulation professionals will handle the installation for you, here are some things to keep in mind about removing old insulation and installing new insulation over old insulation, according to ENERGY STAR:

  • “Faced” insulation should not be placed on top of existing insulation in the attic. Any new batt or roll insulation installed over existing insulation in the attic needs to be without a vapor retarder (face). The vapor retarder on top of or between layers of insulation can trap moisture. Any existing batt or roll insulation in the attic should have the facing against the attic drywall floor or no facing at all.
  • Insulation should be rolled out perpendicular to the joists — and unfaced rolls should be used.
  • Rolled insulation should not be tacked down. The R-value can be reduced if the insulation is squashed or flattened.
  • It’s recommended to air seal before installing insulation since air leaks can hinder the performance of insulation and significantly reduce the energy efficiency and comfort of your home.

The most important thing to keep in mind is that you don’t have to worry about all this. Professionals can answer any questions you have about putting new insulation on top of existing insulation — and handle your entire home insulation project.

How to Decide if You Should Remove Old Insulation from Your Maryland Home

You need to evaluate your home’s existing insulation before adding more.

Do not add new insulation over old if:

  • Old insulation is moist or water-stained: As ENERGY STAR advises, signs of wet insulation mean you must find the cause. Otherwise, this issue will happen again and ruin your new insulation. A hidden plumbing or roof leak, if it goes uncorrected, can also lead to unhealthy mold growth and even structural damage from wood rot or insect infestations.
  • You have vermiculite insulation material: This insulation may contain asbestos. It should not be disturbed and must be removed by trained and certified professionals. Breathing asbestos, especially over a long period of time, can lead to lung disease. According to the EPA, there is no safe level of asbestos exposure.

Best Practices for Adding Home Insulation

Our insulation professionals follow these established industry practices to ensure you get the best performance and highest level of energy efficiency from your insulation installation.

When adding new insulation, remember these tips:

  • Vapor barriers: Do not install insulation with a vapor barrier or facing on top of any other insulation because doing so causes condensation/moisture in an area that should remain dry.
  • Roll or batt insulation: This type of insulation (typically fiberglass or cellulose insulation) can be added over existing insulation, provided it’s installed perpendicular to joists. Do not tack down roll or batt insulation because compacting reduces its effectiveness, or R-value.
  • Loose-fill insulation: This can be added on top of old insulation.
  • Whole-house air sealing: This is an ideal first step before installing insulation because leakage can reduce energy efficiency and compromise your home comfort.

Let Your Local Maryland & Washington, DC Insulation Experts Handle It!

Adding Fiberglass Insulation to a Maryland HomeAccurate Insulation is happy to handle all the details of your new insulation installation, including old insulation removal, if necessary. After evaluating your home’s insulation, home size and other details, we can explain the best insulation strategy for your needs. Then, we’ll perform flawless insulation installation with your satisfaction guaranteed.

Frequently Asked Questions

How do I know when I need more insulation in my attic?

The simplest answer is to look, measure and audit. From the attic hatch, look around in every direction. If you can see the floor joists (boards about eight inches high spread a few feet apart across the attic floor), you probably need more insulation.

What is the best material to use when adding more insulation to an attic?

Loose-fill fiberglass is the best insulation material to use when adding more to your attic.

Can you put blown insulation over rolls?

Adding blown-in insulation over existing rolls is not a problem. It’s important to air seal the area before adding new blown-in insulation, so it works well to keep your home energy-efficient.

Can you put faced insulation over faced insulation?

No, faced insulation should not be added over existing insulation since the vapor retarder on top of or between layers of insulation can trap moisture.

Let Accurate Insulation handle your home insulation project from start to finish. Contact us online or give us a call today.

Products We Install

Our insulation team adds energy efficiency, comfort & value to homes & buildings.

Spray Foam

Accurate Insulation is proud to be a leading installer of spray foam insulation.


Environmentally friendly and effective, cellulose works well in homes and buildings.

Radiant Barrier

We can help keep your home cooler and more comfortable with an attic radiant barrier.

Garage Doors

When you turn to Accurate Insulation for garage doors, you work with a great team.


No matter your gutter needs, the Accurate Insulation team has you covered.

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