How to Install Attic Insulation over Existing

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Attic insulation to many California residents seems like a “set it and forget it” type of material, especially since it may not be visible from behind attic walls. With many homeowners barely spending time in their storage room of an attic, they also feel it’s not a necessary room to maintain.

However, the peak of your home is where hot air rises and escapes with shoddy insulation. It’s also where cool winter air seeps in, rivaling your heating system and increasing utility bills. To discover how to install attic insulation over existing insulation or how to replace it entirely, contact Attic Projects in Los Angeles and the surrounding California areas for licensed, five-star repairs.

Attic Insulation Over Existing

How to Decide if You Should Remove Old Insulation

If you’re wondering whether adding insulation to an attic with existing insulation is possible, it is common to place new insulation over the old. It’s more cost-effective than removing the existing layer and a quicker alternative to an energy-efficient home. However, certain factors demand the instant removal of your old insulation for safety.


Your insulation doesn’t receive outdoor exposure and, therefore, should never be wet. Still, dampness and water stains occur when holes or cracks in your roof or walls promote leaks that eventually damage the wooden structure of your home. Leaking pipes in your walls also create an ideal environment for toxic mold and mildew growth that would only damage your new insulation too.

Before replacing your damaged insulation, scope out the problem and alleviate it.


Water damage isn’t the only concern. If you’re wondering how to install attic insulation over existing insulation with the following issues, you shouldn’t:

  • Crumbing from insect or rodent wear and tear
  • Insulation thinning in certain areas
  • Animal droppings, eggs, or nests in the insulation

Vermiculite Insulation

The answer to “can you put new insulation over old insulation?” is an automatic no if you have vermiculite insulation. Vermiculite insulation, pebble-like and either silver, brown, or gray in appearance, was primarily used until the 1950s. Unfortunately, it contains traces of asbestos that could lead to lung disease if not immediately stripped away by a professional.

Things to Keep in Mind When Installing New Insulation

If your old insulation is up to par, you may now consider how to install attic insulation over existing insulation. Keep the following options in mind with new installations.

  • Roll (or batt) insulation consists of rock wool or fiberglass material that works great as a second layer of insulation as long as a professional installs it perpendicular to floor and wall joists. However, a contractor should never tack it down since it’ll compact it, rendering it ineffective.
  • Blown-in or loose-fill insulation fills spaces of any size and shape since a contractor blows the loose fiberglass and foam material into areas rather than laying down solid blankets.

Consider whether you or a loved one is allergic to any insulation material and whether it’s energy efficient enough. While R-values diminish the cheaper the product is, you should also find the best balance between your budget and product quality.

Best Practices for Installing New Attic Insulation Over Old

Despite your insulation choice, never use vapor barriers or faced insulation when placing new insulation over the original. Faced insulation typically has a foil, vinyl vapor, or paper exterior, while vapor barriers, a type of faced insulation, specifically comprise plastic or kraft paper. These materials lock moisture out, protecting the new installation from deterioration, mold, and mildew growth.

However, while faced insulation is ideal for a standalone layer, the vapor retarder traps moisture within the original insulation if you layer it. Because the old insulation won’t be able to breathe, water will build up faster, rapidly creating an attic structure concern.

Other quality practices when adding more insulation to attic spaces include proper insulation laydown. Insulation should sit between the joists, and a second layer should sit perpendicular to the first, covering the joists. Also, never flatten or tack roll insulation since it removes air pockets, decreasing its R-value.

Pros and Cons of Putting New Installation Over Old Insulation

Sometimes, weighing the pros and cons of adding insulation or starting fresh by ripping out the existing provides more clarity.


  • No need to remove existing material, especially if it doesn’t contain dangerous asbestos, limiting the time and energy that goes into this repair.
  • More energy-efficient since two layers of proper insulation work together to keep warm and cool air where it needs to be without it seeping in or out of your home.
  • More budget-friendly since you’re not only saving money by not tearing out the original insulation, but you can use cheaper new insulation as an addition to the old.


  • Professionals cannot layer any type of insulation with a vapor barrier, giving you fewer options for the second coat of insulation.
  • It’ll be hard to determine or treat a problem evolving under the second insulation layer.

Frequently Asked Questions (FAQs)

Do I need to remove Old Insulation before installing the new one if the existing one is faced?

Since you cannot layer faced insulation, neither the first nor the second layer can contain the vapor barrier since it’ll lock moisture between the layers. Therefore, you must remove the existing faced layer to place a new faced or unfaced insulation layer.

Should you remove Old Insulation before adding new Blown Insulation?

Blown insulation is the best choice if you’re considering how to install attic insulation over existing insulation. The fiberglass not only fills any vacant areas within your walls with loose, unformed fluff but compliments any previously set insulation without harming it.

Attic Projects Company: Our Name, Our Specialty

Ripping out and installing new insulation is an intricate process that takes a professional’s touch. Therefore, leave it to our licensed, bonded, and insured in-house team of experts.

At Attic Projects, we work tirelessly to prepare your home for all seasons while striving to beat all other prices. For more on how to install attic insulation over existing insulation, call 858-302-4082 in San Diego or 714-735-4301 in Orange County and begin a free inspection today!

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Customer Reviews

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I was extremely satisfied with the work done by the attic cleaning crew. They were punctual, friendly, and incredibly skilled at what they do. They were respectful of my property and took great care to protect my belongings while working. I am grateful for their hard work and dedication, and I can confidently say that I will be relying on their services again in the future. Thank you for a job well done!
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