Should You Remove Old Insulation Before Adding New Insulation?

If your home’s insulation has reached the end of its life span, you may wonder: should you remove old insulation before adding new? Fortunately, in most cases, you don’t have to remove old insulation before you add a fresh layer. However, you should consider the type and amount of insulation you have as well as its current condition. Here’s what you need to know about whether to remove your insulation before calling a pro to install new insulation.

When Should You Remove Old Insulation?

Whether you’re renovating your home office or sprucing up the kitchen, you might find you need to first remove the old insulation. Ineffective insulation leads to higher energy bills, poorly functioning HVAC units, multiple moisture-related problems, and more. 

Here are a few scenarios where you should absolutely replace your home’s insulation before installing new insulating materials. 

You’re Installing Spray Foam Insulation

If you’re hiring a local spray foam insulation contractor, you should remove any pre-existing insulation before going ahead with the project. Why? Spray foam insulation creates an ultra-tight air seal, which is one of the primary reasons homeowners end up choosing this type of insulation. 

A tight air barrier means lower energy bills, reduced noise throughout the home, and an increase in the effectiveness of your heating and air conditioning units. But spray foam cannot expand to create that sought-after air seal if there’s a bunch of old insulation in the way. 

A competent pro will bring a powerful vacuum to suck up old fiberglass or cellulose so the spray foam can squeeze its way into every nook and cranny. If needed, the same pro will carry away old fiberglass batts so that you don’t have to haul away junk yourself.

You’re Installing Faced Insulation

Faced insulation features a vapor barrier, otherwise known as a vapor retarder, that prevents moisture from moving from one space to another. This facing, as it’s called, also protects the surface of the insulation and helps fasten it to various building components. Faced insulation is incredibly useful when it comes to reducing moisture and preventing mold, but only if it’s placed correctly.

A general rule of thumb? Don’t install faced insulation on top of existing insulation unless it’s the final insulating layer and the barrier is placed toward the interior of the home. Any other setup creates a moisture pocket, which is a breeding ground for mold and rot.

You’ve Had Rodents or Pests

Rodents and other pests love to make their home inside of loose-fill insulation and fiberglass batts. Both are pretty cozy, after all. If your insulation has become a critter condo, remove it before adding any new insulating materials. Why? Rats and related pests leave behind urine and droppings, which permeate the insulation itself and can spread some pretty bad diseases. 

There is no real way to separate these nasty substances from the insulation, so your best bet is total removal. Before installing insulation, sanitize and disinfect the area for added peace of mind.

You’ve Experienced Water Damage

Water may make for a refreshing drink, but it should not go anywhere near your insulation materials. If you’ve experienced a roof leak, flood, or even just spilled condensation from an air conditioner, you should check on your insulation.

Insulation holds moisture for a long time and becomes the perfect environment for mold spores and mildew. Yuck. Even worse? Water damage causes the insulation to lose its effectiveness and ability to reduce energy loss—also known as insulation R-value. This will slow down the transfer of heat throughout your home and make it hotter inside in the summer and colder inside in the winter. And most people don’t want to live in a sauna or experience a winter wonderland inside.

Remove that old waterlogged insulation before adding anything new. You can, however, be surgical about it by learning how to cut insulation. Getting rid of only the affected patches of insulation can save you on replacement insulation costs, which can go for anywhere between $1.50 and $8.75 per square foot, including labor and removal costs.

When Should You Keep Old Insulation?

You don’t always have to remove old insulation. Sometimes it’s totally acceptable—or even best—to add new insulation to old insulation to make one big happy insulating family. 

You’re Adding Loose-Fill Insulation

Loose-fill insulation is great for adding to pre-existing insulation. You can squeeze some in anywhere, and there are no potentially harmful chemical interactions between mixing loose-fill and other types of insulation.

Even cooler? Adding new loose-fill insulation to old insulation should add to your home’s R-value, saving you money on that monthly energy bill and increasing the overall effectiveness of your building’s insulation.

Of course, you should only add loose-fill insulation to old insulation if the old stuff is in good shape. If there is water damage, mold, rodents, or evidence of fire damage, toss that old insulation out as a precautionary measure.

You’re Adding Batt or Rolled Insulation

The same goes for batt or rolled insulation, whether it’s made from fiberglass or cellulose. These insulation types retain their R-values and continue to operate effectively so long as they avoid moisture, mold, rodents, and the like. So mix and match to your heart's content, with one major caveat. 

If you have conducted an energy audit and the report indicated a multitude of misaligned insulation rolls or batts, removal could be the easiest option. Misaligned insulation still has its insulative properties, but the misalignment has rendered it useless. 

Depending on the design of your house, a qualified pro could recommend removal and reinstallation or something called the “lift and fill” method. In this scenario, technicians lift up each roll or batt and blow loose-fill insulation underneath, creating a cushion to fix the alignment issue.

How Long Does It Take To Remove Old Insulation?

How long it takes to remove the insulation varies by the size of your home, the type of insulation, and any complications that may arise, but anticipate this project taking anywhere between four and 24 hours to complete for a standard 1,500-square-foot space. 

Removing old insulation can be a time-consuming project. You need to have a dumpster on site to dispose of the old insulation and, in some cases, specialized equipment to get the job done. Here’s a breakdown of each type of insulation and how the removal method could affect the time it takes to dispose of the insulation.

• Batts and rolls removal: Fiberglass insulation removal is one of the most straightforward types of insulation to remove. The same goes for cellulose and rockwool insulation that come in batts and rolls. You simply remove each piece of insulation and dispose of it. It can be laborious, however, to dispose of these materials.

• Blown-in insulation removal: This material requires a bit of a learning curve, as you need an insulation vacuum to do the job. However, it’s a quick process because the vacuum disposes of the insulation into a bag for an easy cleanup. 

• Foam board insulation removal: Foam board panels are another easy type of insulation to remove, as you just need to take the old panels out of the wall and dispose of them. Their light weight makes for an easy disposal process. 

• Spray foam insulation removal: You’ll find that spray foam insulation is one of the more challenging and time-consuming types of insulation to remove because it's a permanent material. With this insulation, you need to use a knife, saw, or specialized equipment to scrape away the spray foam.

Most Common Batt and Roll Insulation Projects

According to Angi data, only about 8% of common batt and roll insulation projects involve repairing or replacing this type of insulation. So, homeowners can expect batt and roll insulation to have good longevity, making it a worthwhile investment. 

DIY vs. Hiring a Pro to Remove Old Insulation?

If your home improvement project includes insulation, you’ve likely looked into hiring insulation contractors to insulate your attic, crawlspace, rim joists, or open walls. After all, insulation can irritate your eyes, throat, and lungs, cause itchy skin, and trigger allergy symptoms and asthma.  

Old houses, especially, can have asbestos insulation, which can contain dangerous particles that carry carcinogen risks. It’s important to know what asbestos insulation looks like to protect yourself from exposure. Vermiculite insulation is another dangerous type of insulation used in older houses that contains trace amounts of asbestos.

It’s best to play it safe and contact a local insulation company to remove old insulation. Your pro knows how to install new insulation and remove old insulation. They also have all the tools and skills to safely remove old insulation so that you don’t have to put yourself in harm’s way.