What is the downside of foam insulation?

Author: Barrett McLaughlin  |  Last update: Wednesday, July 8, 2026

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.

Why don't insurance companies like spray foam?

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.

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.

When should you not 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.

Spray Foam Insulation — The Ugly Truth?

What is the downfall of spray foam insulation?

While spray foam insulation can make a home more energy efficient, its downsides often out-weight its benefits. If spray foam insulation isn't installed correctly or is used in the wrong setting, it can cause all sorts of problems, from reducing ventilation to rotting wooden roof beams.

How much does it cost to spray foam for 1500 square feet?

The cost to insulate an attic is usually between $1.50 and $3.50 per square foot. This price can change depending on the attic's size and how easy it is to get to. For a typical 1,500-square-foot attic, you pay $2,250 to $5,250.

What is the best alternative to spray foam insulation?

The best alternative to spray foam insulation is Multifoil Insulation. The reason being is that it incorporates the 'good' of the traditional insulation, whilst not having any of the drawbacks that spray foam insulation possesses.

What happens to foam insulation when it gets wet?

Does foam insulation absorb water? No, premium spray and injection foam do not absorb water. They resist moisture, making them an excellent choice for areas prone to humidity or minor water exposure.

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 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.

What is the downside to foam insulation?

The discussion around the dangers of spray foam insulation often includes the potential for respiratory problems, particularly during the installation process and while the foam is curing. Furthermore, some spray foams can off-gas volatile organic compounds (VOCs), leading to indoor air quality issues.

Does homeowners insurance cover insulation?

Insurance Coverage: Homeowners insurance may cover insulation damage if it's tied to a covered peril, such as a sudden water leak or storm damage. Alternative Solutions: Specialized insurance policies, energy efficiency programs, or direct rebates may help defray insulation-related costs.

Is spray foam a bad investment?

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

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.

Is spray foam a tax write off?

The Insulation Tax Credit covers energy-saving upgrades beyond insulation. Here's a breakdown of eligible items within the $1,200 annual limit: Insulation and Air Sealing: Qualifying insulation materials include blow-in, rigid boards, batt insulation, and expanding spray foam, among others.

Does foam get moldy when wet?

Open-cell spray foam is more porous than closed-cell foam, so it may absorb water if it gets wet. This can lead to decreased R-value and, over time, the potential development of mold or mildew if the moisture is not properly addressed.

Does great stuff spray foam absorb water?

In contrast, Great Stuff™ is closed-cell foam. It forms a water-resistant outer coating when cured. Latex foam does not expand.

Does humidity affect spray foam insulation?

Humidity and Moisture Levels: High humidity or moisture levels can affect the adhesion and curing process of spray foam insulation. It's important to ensure that the area being sprayed is dry and free from excess moisture.

Why not to get spray foam insulation?

Aside from its relatively high cost, it has been reported as reducing ventilation, with humidity and dampness resulting in the deterioration of structural timbers. Spray foam insulation has also come under criticism for being: Difficult to remove once it's been installed.

Why can't you sell a house with spray foam insulation?

Independent chartered building surveyor, Geoff Hunt said due to government initiatives open cell spray foam has gained popularity in recent years. But he called for 'caution and refusals on higher-risk applications' as mortgage lenders struggle to assess spray foam.

What is the best R-value insulation?

Rigid foam board insulation is available in many materials, including polystyrene (R-3.8 to R-5.0), polyurethane (R-5.5 to R-6.5) and polyisocyanurate (R-5.6 to R-8.0). Since it has the highest R-value, rigid foam is typically reserved for foundations and basement walls.

Is 3 inches of spray foam enough?

For wall insulation, the recommended spray foam insulation thickness using closed-cell spray foam should be between 2 to 3 inches. A thickness of 4 to 5 inches will suffice for ceilings and roof decks.

Can I do 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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