Is there a downside to spray foam attic?

Author: Prof. Clara Johnston  |  Last update: Thursday, April 30, 2026

Due to its quick and straightforward installation process and affordable pricing, spray foam insulation is quickly becoming a popular product. However, there is a chance that the insulation in this product will start to shrink over time, which will lessen its insulating capabilities.

What are the cons of spray foam attic insulation?

  • It's not eco-friendly. ...
  • Spray foam insulation can cause roof damage. ...
  • It can cause health complications. ...
  • Spray foam insulation can cause bad smells. ...
  • Mould and mildew is (sometimes) a problem.

When not to use spray foam insulation?

Directly against electrical wiring or fixtures: Spray foam insulation should not be applied directly against electrical wiring, fixtures, or recessed lighting unless they are rated for contact with insulation. Contact with insulation can cause overheating and pose a fire hazard.

Why is spray foam a red flag for lenders?

Spray foam insulation is one of those many factors that can throw up a red flag to a mortgage lender. For a lender, your insulation matters because it affects crucial metrics such as the home's saleable value and energy efficiency rating.

How much does it cost to spray foam an existing attic?

Project Size and Insulation Location

For example, using open-cell spray foam, the attic spray foam insulation cost is between $3,500 - $5,000, while closed-cell spray foam costs range from $4,500 to $7,000 for the same project size.

What is the Best Attic Insulation? (Spray Foam vs. Fiberglass vs. Cellulose) | Foam University

Where not to use expanding foam?

While it is hugely useful, it should not be used to solve all problems. One such example is electrical boxes. Expanding foam shouldn't be used in these locations as it could cause jams that would be expensive to repair. So avoid using it around sockets or light fixtures, or any electrical components in the property.

Why do insurance companies not like spray foam insulation?

The chemical aspect of spray foam makes it very hard for standard insurance companies to provide coverage. Most standard lines insurance carriers want to write the risks with no liability not spray foam contractors that manufacture plastic every day in the field.

Why is it hard to sell a house with spray foam insulation?

Some Buyers May Be Uncertain Of Spray Foam Insulation.

If they don't know the contractor who installed it, they may worry that the foam was installed by people who didn't know what they were doing. Other buyers have heard negative stories about spray foam insulation.

What not to tell a lender?

5 Things You Should Never Say When Getting a Mortgage
  • 'I need to get an extra insurance quote due to … ...
  • 'I can't believe how much work the house needs before we move in' ...
  • 'Please don't tell my spouse what's on my credit report' ...
  • 'I'm still working out the details on my down payment'

Should you spray foam the underside of your roof?

Spray foam can provide the thermal, air, and vapor control layers in both new and retrofit construction. Unvented roof strategies with open cell and closed cell SPF insulation sprayed to the underside of roof sheathing have been used since the mid-1990s to provide durable and efficient building enclosures.

What type of spray foam is best for an attic?

For Attics In Climate Zone 5, We Recommend Open Cell Spray Foam. You can still insulate your attic with closed cell spray foam. However, if you are looking to save some money on your project, open cell spray foam is the choice product for attics.

Can I sleep in my house after spray foam insulation?

Spray foam is safe after a minimum of 24 hours. In some cases, the spray foam insulation company may ask the homeowner to stay out of the house for 48 hours just to be sure no one inhales any of the off-gas. After the curing process is complete, homeowners do not need to worry about inhaling any chemicals.

Can mold grow behind spray foam insulation?

Mold and mildew can begin growing behind the insulation which can go unnoticed until it's already become a huge problem. This often happens when the spray foam isn't installed correctly and space is left between the insulation and the wall, which allows moisture in and gives mold the perfect place to grow, unfettered.

Do you need an attic fan with spray foam insulation?

Proper Attic Ventilation

Without ventilation, moisture can accumulate and cause mold, mildew, or damage to the roof. If spray foam is instead applied to the attic ceiling, ventilation may not be needed. An exception is with wood, tile, slate, or some asphalt shingle roofs that require an air gap for their warranties.

What are the disadvantages of foam?

One of the main drawbacks of polyurethane foam is the potential for chemical emissions. Volatile organic compounds (VOCs) released during manufacturing and off-gassing can affect indoor air quality. Polyurethane foam is highly flammable.

What are the negatives of spray foam?

Spray foam insulation is a good insulator in terms of keeping a room warm or cool. But its many downsides outweigh the benefits. These include, making it more difficult getting a mortgage, potential health issues, environmental damage, ventilation issues and a lower home valuation.

Does homeowners insurance cover attic insulation?

If the attic damage was caused by a covered risk, such as fire or wind, your home's insurance policy may pay the cost of rehabilitation. Repairing or replacing damaged insulation, drywall, and other materials could be included.

Why are lenders rejecting spray foam insulation?

The issue stemmed from older homes being retrofitted with spray foam insulation in the roof line, leading to moisture buildup and potential rot issues. The lack of a vapor barrier and inadequate insulation thickness contributed to the problem.

What is better than spray foam insulation?

While both types of insulation are great choices for home insulation, fiberglass insulation is generally considered to be safer than spray foam insulation. This is because spray foam contains a special type of chemical called isocyanate, which is toxic when inhaled.

Is spray foam a bad investment?

Spray foam insulation is expensive but can be an excellent investment for residential and commercial properties.

How much does it cost to foam insulate an attic?

To give you an idea, the average cost to spray foam an attic in an existing home typically ranges from $5,100 to $10,300.

Why is spray foam hazardous?

Spray application generates isocyanate vapors and aerosols. Research data indicate that inhalation exposures during SPF insulation will typically exceed Occupational Safety and Health Administration (OSHA) occupational exposure limits (OELs) and require skin, eye and respiratory protection.

What destroys expanding foam?

Yes, WD-40 does remove expanding foam as it can break down the foam residue.

Can I spray foam insulation myself?

The answer is yes, but drywall needs to be removed before you can install the foam. Spray foam expands rapidly when it is applied to the inside of walls. If you try to add the insulation without removing drywall, the expanding foam may overfill the panel and exert pressure against the inside of the plasterboard.

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