Telegraphing Roof Concerns With Closed-Cell Foam Insulation: What to Know for Your Next Attic Ventilation Inspection

Welcome to the Inspection Insider. Here, seasoned home inspectors share their technical expertise and experience to help you improve your own inspections. 

In this post, Lisa Alajajian Giroux of HomeQuest Consultants in Massachusetts shares how spray foam insulation can lead to roof defects and claims. Alajajian Giroux is a former ASHI President and the 2026 President-Elect, an ASHI Certified Inspector, and a home inspector of 27 years. She advocates home inspector mentorship, continuing education, and thorough reporting. Follow Lisa Alajajian Giroux on Instagram to see how she encourages clients and agents to get inspections.

Now, here’s Alajajian Giroux with her article on closed-cell foam insulation during attic ventilation inspections.

Telegraphing and Home Attic Ventilation

When I enter a new construction development, I drive around the entire area and look at roofs. I often see roof telegraphing, where the shingles become distorted or uneven. This exposes a visible “telegraph” pattern with the underlying structure showing through the surface of the shingles. Telegraphing can show suspected evidence of water intrusion, water damage, and subsequent sheathing rot.

Some common reasons for telegraphing include:

• Improper shingle and underlayment installation can lead to the shingles lifting, curling, or showing uneven patterns.
• If the roof decking has irregularities such as dips or bumps, these imperfections can telegraph through the shingles.
• Wear and tear can damage, curl, or buckle the shingles and exacerbate existing issues.
• Moisture-related issues like rot beneath the shingles can make the surface uneven.
• Spray foam insulation that has not been mixed or applied properly.

Spray foam insulation often catches clients by surprise. Worse still, most shingle manufacturers refuse to cover warranty claims when spray foam insulation is used. And if the manufacturer won’t pay for a roof repair or replacement, the unhappy home buyer will likely turn to the builder—and you, the home inspector, who performed the attic ventilation inspection. 

“Shouldn’t you know attic ventilation requirements and standards?” they might ask. 

“Why didn’t you tell me spray foam insulation could cause problems?”

To protect your clients and you, let’s talk about closed-cell spray foam insulation: what it is, why it’s a problem, and how to report it.

What is attic ventilation?

Roof attic ventilation is how air and moisture enter and leave the home through natural openings, like windows and doors, and mechanical systems, like vents, fans, and ducts. Openings in roof framing and ridging play a part in proper attic ventilation.

There are two types of mechanical ventilation: Heat Recovery Ventilation) (HRV) and Energy Recovery Ventilation (ERV). These mechanical ventilation systems are designed to improve indoor air quality by providing fresh air while minimizing energy consumption. 

So that you know what to expect during attic ventilation inspections, here’s a breakdown of each:

Heat Recovery Ventilator (HRV):

• Function: This attic ventilation system exchanges stale indoor air with fresh outdoor air. During colder months, it recovers  heat energy from the outgoing air to warm the incoming fresh air.
• How It Works: The HRV unit contains a heat exchanger, which transfers heat between the outgoing and incoming air without the two airstreams mixing. During winter, the warm, stale air from inside transfers heat to the incoming cold air, reducing the need to heat the fresh air.
• Best For: Cold climates where heat recovery is essential to maintain energy efficiency in heating.

Energy Recovery Ventilator (ERV):

• Function: Like HRV, an ERV transfers moisture (humidity) between the incoming and outgoing air in addition to heat.
• How It Works: The ERV transfers thermal energy (heat) and moisture between the two airstreams. In the winter, it helps prevent overly dry indoor air. Meanwhile, in the summer, it can prevent excess humidity from entering the home.
• Best For: Areas with high humidity.

Key Difference:

• Moisture Control: ERVs transfer moisture, while HRVs only transfer heat.
• Climate Suitability: HRVs are ideal for cold climates. By comparison, ERVs are better for cold and humid climates due to their moisture control capabilities.

Both systems improve indoor air quality by ensuring continuous ventilation while conserving energy. The choice between an HRV and an ERV depends on the specific climate and the need for moisture control.

Why do builders choose spray foam insulation?

What should you know if clients ask about spray foam insulation after an attic ventilation inspection?

Closed-cell spray foam insulation is commonly used in unvented roof structures to improve energy efficiency and air sealing. It’s often used in attics because it provides thermal insulation and a moisture barrier. 

Closed-cell foam insulation can be an excellent product for thermal and moisture control. However, its success in an attic depends on how well the home is ventilated and prepared. 

What moisture problems can spray foam insulation cause?

What happens if an attic is not vented? Here are two ways spray foam insulation can negatively contribute to a non-vented, conditioned attic space: 

1. Trapping Moisture in the Attic: Closed-cell foam creates an effective vapor barrier. While this is beneficial for preventing heat transfer, the lack of air circulation in the attic can trap moisture. If humid air from the living spaces below the attic can’t escape, that improper attic ventilation can cause moisture buildup, mold growth, wood rot, or damage to the insulation.
2. Condensation Issues: Condensation can form on surfaces like roofing or structural components. This happens if the attic’s humidity level is high and the temperature fluctuates—a sign of poor attic ventilation. Since closed-cell foam prevents air circulation in an attic, this moisture could remain trapped and lead to damage over time.

What to Write in Your Attic Ventilation Inspection Report

You might see spray foam insulation and think, “I don’t need to comment on that. That is beyond the attic ventilation standards, and the municipal inspector signed off and closed the permit.” 

However, that’s the wrong attitude. In fact, it could expose you to a claim.

Municipal inspectors in my state of Massachusetts are immune from prosecution. Buyers can sue their professional contractors for breach of contract and unsafe business practices. Most of the time, upset buyers include the home inspector.

Let me clarify: I do not inspect or write in fear. I inspect and write for the benefit of my client. I am a consumer advocate. It’s as an advocate and a realist that I recommend the following when you find spray foam insulation during an attic ventilation inspection:

1. Know your client.

As a home inspector, who are you writing your report for? Did you skim over anything to save a real estate agent relationship that could come back to bite you? Or are you absolved from reporting noticeable insulation and attic ventilation problems? 

Remember who your client is: the buyer or seller. (Not the agent.) If you see something, say something.

If it’s safe and accessible, walk the attic and look for open gaps, insulation pulled away from a plumbing vent pipe, or other roof penetrations. Report what you see and put your client on notice.

2. Utilize infrared cameras.

An infrared camera can be a valuable tool for detecting moisture issues in an attic with closed-cell spray foam insulation. Here’s how it works and how it can help:

• Temperature Differentials: Infrared cameras detect temperature variations. Moisture in building materials like wood or drywall can affect their thermal properties, causing them to heat up or cool down differently than the surrounding dry materials. The infrared camera can spot these temperature differences, indicating potential moisture issues behind the insulation.
• Condensation Patterns: Moisture buildup may cause condensation, especially without proper attic ventilation. Moisture on surfaces like beams, wood, or spray foam could be cooler or warmer than their dry counterparts, showing distinct temperature patterns on an infrared image.
• Areas of Potential Leaks: If there’s a roof leak or some other form of water intrusion, an infrared camera can show areas of moisture accumulation, even if the damage isn’t visible yet. Due to moisture, wet areas often have different temperatures than dry areas.
• Moisture Trapped Behind the Insulation: If spray foam insulation is improperly applied, moisture can get trapped between the foam and the underlying materials. An infrared camera can reveal cold spots or temperature irregularities that suggest water is present behind the insulation, even if no water is visibly leaking.

In summary, an infrared camera can detect temperature variations caused by moisture in attic materials. These results can pinpoint hidden issues that lead to mold growth, structural damage, or reduced energy efficiency.

3. Know what proper installation and moisture management for spray foam insulation looks like.

Proper installation and moisture management practices will help clients protect the structural integrity of their homes. While, as an inspector, it isn’t your job to inspect for code compliance, including proper installation, understanding best practices can help you pinpoint opportunities for moisture intrusion. Here’s what builders do to prevent moisture problems:

• Air Sealing Before Insulation: Builders should ensure all air leaks into the attic are sealed before installing closed-cell foam. This will prevent warm, humid air from entering the attic and reduce condensation risk. Ducts, plumbing vents, and other air movement pathways should also be sealed.
• Spray Foam Application Details: Builders should apply the foam correctly with sufficient thickness (usually 3-4 inches). This creates a sound vapor barrier while allowing adequate air movement in the attic. An experienced professional should handle this installation to avoid coverage gaps or improper application.

In your report, you can encourage clients to prevent moisture problems by:

• Maintaining a conditioned attic space.
• Regularly monitoring humidity levels in the attic with a hygrometer. If humidity levels are too high, they can use a dehumidifier or improve the home’s attic ventilation. In my area, homeowners use energy recovery and heat recovery ventilators more than ever in new homes.

4. Encourage clients to review their warranty.

Many roofing manufacturers disclaim problems with spray foam insulation in their warranties. To protect your clients, encourage them to review the specific warranty and product documentation for shingles and other roofing materials like spray foam insulation. If in doubt, homeowners can contact the shingle manufacturer directly for clarification. Directing them to the proper source clarifies that your attic ventilation inspection is not responsible for their warranty’s coverage.

Don’t let your clients foam at the mouth after your attic ventilation inspection.

While closed-cell foam insulation is an often utilized product for thermal and moisture control, its success in an attic largely depends on how well the home has ventilated and prepared air exchanges. Proper installation and moisture management practices will help you avoid moisture problems and protect your home’s structural integrity. By examining the roof and attic, utilizing tools like infrared cameras, and being well versed in spray foam insulation, you can provide your clients with exceptional service and prevent them from getting upset later.

We hope you enjoyed Lisa Alajajian Giroux’s article on closed-cell spray foam insulation. Knowledge and expertise can help you navigate attics and roofs with confidence—as can your insurance. 

Whether you’re accused of missing bats in the attic or a leaking roof, or even if your employee experiences heat exhaustion in a poorly-ventilated attic, InspectorPro protects against common claims. Learn how our home inspector insurance solutions provide peace of mind. 

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