Is Spray Foam Insulation Waterproof?

If you’re considering spray foam roofing for your home or commercial property, you might be wondering about its waterproofing abilities.

If you’ve ever Googled “Is spray foam waterproof,” you’ve probably come across conflicting answers. Some say yes, others say no, and a few throw around confusing technical jargon. So, what’s the real story?

As a reputable spray foam roof insulation, “Foam Experts Co.” brings you the straight answers in simple terms.

Is Spray Foam Insulation Waterproof?

The fact is that – “Spray-foam insulation is not water-proof but is highly water-resistant, depending upon the quality of spray foam used.”

This is where the confusion begins! And most people often get it wrong. 

Actually, there are two main types of spray foam insulation, and they behave very differently when it comes to water.

• Closed-cell spray foam is dense and compact. It’s highly water-resistant, repelling water and not absorbing moisture easily.
• Open-cell spray foam, on the other hand, is soft and sponge-like. It can soak up moisture if exposed, so it’s definitely not waterproof.

Usually, contractors don’t tell you the real difference and can mislead you. So before you believe any claim, you need to ask: “What type of spray foam are we talking about?”

Waterproof vs. Water-Resistant: What’s the Difference?

Let’s simplify this –

• Waterproof means no water can pass through, even if it’s fully soaked or underwater for a long time.
• Water-resistant means it can block water to some extent, but if it’s exposed for too long, some water might still get in.

Spray foam, especially closed-cell spray foam, falls in the water-resistant category. You might be surprised to know, but that’s a huge plus for most real-world uses in roofing and industrial insulation.

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Why Water-Resistant Insulation Is a Smart Choice for Roofing?

When it comes to protecting your roof, basement, or commercial building, the first thing that often comes to mind is waterproofing. Right?

And that’s for good because water damage can be costly and frustrating. But there’s another layer to the story that’s often overlooked – “energy efficiency”.

If we ask you one simple question – What’s the main property of insulation? It’s mainly to trap heat and save energy!

But if the insulation material absorbs water, it loses the ability to trap heat. That’s because water conducts heat faster than air. So, if water gets into your insulation, it can make your home or building hotter in summer and colder in winter, leading to higher energy bills.

That’s why we suggest closed-cell spray foam.

• It doesn’t just help block water.
• It also keeps your insulation performing at its best. 
• It seals gaps, prevents air leaks, and resists moisture, even in tough conditions.

Note – “Even if spray foam isn’t fully waterproof, it still does a great job of keeping water out and helping your insulation work better.”

Can Closed-Cell Spray Foam Handle Mold or Floods?

When people hear about spray foam insulation, they often think it’s just good at keeping out air and water. But closed-cell spray foam does a lot more than just resist moisture.

1. Flood-Resistant

FEMA rates closed-cell spray foam as a flood-damage resistant material. That means it can safely withstand up to 72 hours of floodwater exposure without significant damage and be cleaned and reused afterward.

FEMA confirms that a closed-cell spray foam can –

• Survive wetting and drying cycles
• Be power-washed when needed
• Retain performance post-flood, as long as it wasn’t structurally compromised

2. Mold & Mildew Resistant

Because of its dense and sealed structure, closed-cell foam does not absorb water. Unlike many traditional insulation products, it does not provide food or moisture for microbial growth and creates unfavorable conditions for mold and mildew to grow.

3. Vapor & Air Barrier

When applied to a thickness of about 1.5-2 inches, closed-cell foam serves as both a vapor barrier and an air barrier. It helps stop air and moisture from getting in or out, keeping your building well-sealed and energy-efficient.

4. High R‑Value Per Inch

Closed-cell spray foam packs a lot of insulation power into a small space, making it a smart choice for commercial roofs or buildings that need an upgrade.

Don’t wait—contact us today for trusted spray foam roofing!

We’ll Answer Your Other Queries on Spray Foam Roofing

1. If spray foam insulation gets wet, does it dry out and recover?

With closed-cell foam, yes, if it’s not continuously submerged for long periods. It repels water and doesn’t absorb moisture, so it can dry and maintain its insulating properties. But open-cell foam, by contrast, absorbs water and loses effectiveness if exposed.

2. Are there any downsides or limitations to closed-cell spray foam?

Yes, there are a few things to consider.

• If spray foam is applied the wrong way, it can trap moisture against wood, which may lead to damage over time, especially on certain surfaces like OSB boards.
• Correct installation is important as misapplication can lead to off-gassing, uneven cure, or hidden leaks that may remain undetected under the foam.

3. How do I choose the right type of spray foam? 

If you need reliable water resistance, energy efficiency, and durability, closed-cell spray foam is the best choice. It has a higher R-value (around R‑6 to 7 per inch) and resists moisture far better than open-cell foam, fiberglass, or cellulose.

Takeaway

There is no insulation material available in the market that’s waterproof. Closed-cell spray foam is one of the most water-resistant types of insulation you can get. It gives great protection against moisture.

If you want it to last long and see the effective results, get it installed by pros only.

Read More About:

• How do I know if my roof is going to collapse
• How to Fix Roof Leak Around Chimney?
• Why Early Roof Leak Detection is Critical for Foam Roofs
• Why Spray Foam Roofing is the Best Choice for Commercial Buildings

Protect Your Roof With Foam Experts Co. – Redding’s  #1 Choice for Spray Foam Roofing

With over 40 years of experience in industrial roof service in Redding, we at Foam Experts Co. don’t just install spray foam. We engineer it to perform under your property’s unique conditions. 

We are licensed, insured, and deeply familiar with local building codes and climates. If you’re looking for spray-foam insulation, contact us. Our highly trained crews will get the job done right the first time!

Our roofing services are available for all commercial and industrial sectors in Redding!