Attic insulation: should the old glass wool be removed?


Do you think about your attic often? If you're like most people, probably not. Yet your attic can be a source of wasted energy and high utility bills if you're not careful. Fortunately, there is a simple and effective way to improve the energy efficiency of your home: attic insulation. So why not take advantage of it?

Have you decided to install insulation in your attic? It's a great idea! Indeed, by insulating your attic, you can save up to 30% of energy. And there are many types of insulation to achieve this, natural, mineral or synthetic.

Among the best known, we find the glass wool (+kraft)made from glass and very popular, the cellulosemade from recycled paper products and with good thermal performance, the rock woolthe perlitethe sheep's woolthe strawetc. It's up to you to choose the one that best suits your needs and your budget!

Most experts agree that fall or winter is the best time to do this, as the cooler temperatures reduce the risk of condensation problems due to moisture. However, it is also possible to insulate your attic in the spring or summer, as long as you take a few precautions to avoid moisture problems.

You've decided to insulate your attic to improve your home's energy efficiency, but you're wondering if it's necessary to remove the old insulation before proceeding? There is no single answer to this question, it all depends on your situation. To help you make an informed decision, let's review the pros and cons of removing old insulation before installing new.

Why should you insulate your attic?

The benefits of attic insulation.

There are many reasons why you should insulate your attic. One reason is that it will save you money on your energy bills. Attic insulation helps keep your home warmer in the winter and cooler in the summer. This means you won't have to use your heating and cooling systems as much, which will save you money.

Another reason to insulate your attic is that it can help improve the indoor air quality of your home. Insulation helps keep outside air out of your home, which can help reduce the amount of pollen, dust and other allergens that can cause problems for allergy and asthma sufferers.

Insulating your attic can also help reduce noise from outside. If you live in a busy area or near a highway, insulation can help reduce the amount of noise that enters your home.

Finally, attic insulation can help protect your home from damage caused by extreme weather conditions. In the event of a severe storm or hurricane, insulation can help protect your roof from wind or rain damage.

Do I have to remove the old glass wool?

The debate about removing the old insulation.

When you decide to insulate your attic, you may be wondering if it is necessary to remove the old insulation before installing the new one. There is much debate about this question and it is difficult to find a single answer, as each situation is unique and requires a thorough evaluation.

Some professionals say that it is essential to remove the old insulation to ensure optimal insulation and to prevent any risk of damage to your attic. They say the old insulation may be in poor condition, contain impurities or be too thick, which can hinder the performance of the new insulation. Others argue that leaving the old insulation in place can be an economical and ecological solutionprovided that check that the insulation is in good condition and does not obstruct air circulation.

It is therefore important to take the time to assess your situation and consult a qualified professional before making a decision. Depending on the condition of your attic, your needs and your goals, you will be able to determine whether or not to remove the old insulation. Don't hesitate to ask for several quotes and make comparisons to find the best solution for your situation.

The advantages and disadvantages of removing old insulation.

There are several benefits remove the old glass wool insulation before re-insulating your attic:

  • Guarantee optimal insulation: By removing the old insulation, you can ensure that the new insulation will be placed evenly and uniformly. This will give you maximum thermal and acoustic insulation, and significant energy savings.
  • Preventing the risk of degradation: If the old insulation is in poor condition, for example if there are holes, cracks or mold, it is recommended that it be removed before installing new insulation. This will prevent any risk of degradation of your attic and preserve its life. Also, by removing the old insulation, you can reduce the risk of pests such as bed bugs or mice, which can settle in the insulation and cause damage.
  • Facilitating the work: By removing the old insulation, you will have easier access to the various elements of your attic and will be able to do the work more quickly and efficiently. This will help you minimize the costs associated with insulating your attic.
  • Improve the aesthetics of your attic: By removing the old insulation, you can choose to install new insulation in a different color or finish, giving your attic a fresh, more aesthetically pleasing look.

Some of the disadvantages include:

  • Additional cost: Removing the old insulation may involve additional costs, including removal and disposal of the old insulation. If you decide to remove the old insulation, it is important to factor these costs into your budget and compare quotes from professionals.
  • Ttion of additional work : Removing the old insulation usually involves additional work, such as dismantling the insulation and cleaning up the attic. If you decide to remove the old insulation, it is important to allow enough time for the work and to make sure it is well organized.
  • Dust hazard: Removing old insulation can generate dust, which can be unpleasant and harmful to your health. If you decide to remove the old insulation, it is recommended that you take the necessary protective measures, such as wearing a mask and gloves, and ventilate the attic regularly.
  • Risk of damage to wiring and conduits: Removing the old insulation can cause damage to the wiring and ductwork in your attic. If you decide to remove the old insulation, it is important to hire qualified professionals who can handle the insulation safely and minimize the risk of damage.

How to remove old insulation.

Steps to remove old insulation.

To remove your old glass wool insulation, here are the steps to follow:

  1. Prepare the work area: Before you begin, it is important to clean the area where you will be working. Remove all items stored in the attic and vacuum up any dust and debris that has accumulated on the floor and on the insulation.
  2. Remove the insulation: To remove the insulation, you can use a power strip or an electric knife. Be sure to wear gloves and a mask to protect yourself from the insulation particles. If you use an electric knife, make sure the blade is well away from your skin. Remove the insulation in small pieces and place them in trash bags for later disposal.
  3. Dispose of insulation responsibly: Glass wool insulation should never be thrown in the garbage, as it can be harmful to the environment. Contact your local waste management company to find out how to properly dispose of it.

It is recommended that you hire professionals to remove the old insulation from your attic, especially if you are not experienced with this type of work. Professionals have the skills and equipment to remove the insulation safely and effectively without damaging your attic.

The tools you will need to remove the old insulation.

In order to remove the old insulation safely and efficiently, there are a few tools you will need:

  • Vacuum cleaner or broom: To remove dust and debris accumulated on the floor and on the insulation.
  • Protective gloves: To protect your hands from insulating particles and possible sharp debris.
  • Protective mask: To protect your nose and mouth from insulating particles.
  • Electric knife or multi-socket: To remove insulation in small pieces. Be sure to follow the tool's safety instructions and wear protective gloves.
  • Garbage Bags: To put the pieces of insulation to be removed.


There are many debates about whether or not to remove the old insulation before re-insulating your attic. Some people feel that removing the old insulation is necessary for the best results, while others feel that it is not necessary and may even be harmful.

It should be noted that removal of the old insulation may be necessary in some cases, particularly if the insulation is in poor condition or if there is a risk of deterioration. In other cases, it may be preferable to leave the old insulation in place and cover it with an additional layer of insulation.

It is important to take the time to assess your situation and consult a professional before making a decision.

The professionals have the skills and experience to help you determine the best approach for your attic. Ultimately, whether or not to remove the old insulation will depend on your unique situation and your goals for energy efficiency and thermal comfort.

Julien G.

Juliena mechanical engineering graduate and specialist in climate engineering since 2009, has become a writer specializing in renewable energies, with expertise in heat pumps and photovoltaic solar panels for individual housing.
See all articles by this author