Does Injection Foam Shrink Over Time? Let’s Clear Up the Confusion

If you’ve been researching insulation options for your existing home, you’ve probably come across injection foam—a popular solution for improving comfort and efficiency without tearing down your walls. And if you’ve been reading through the comments online, you may have seen this one pop up:

“Doesn’t that foam shrink over time?”

It’s a totally valid concern—and one we hear often. But to answer it properly, we need to take a quick trip back in time and look at how foam insulation has evolved since the early days.

The Short Answer

No—modern injection foam does not shrink over time in a way that impacts performance. The confusion stems from much older products that were used decades ago and had very different chemical compositions than what we use today.

Let’s break it down.

A Brief History: Where the Shrinking Myth Comes From

Back in the 1970s and 1980s, injection foam insulation was still relatively new. At the time, there were a few products on the market intended to be injected into the walls of existing homes to improve insulation value. But unfortunately, those early formulations weren’t very stable over time.

What happened?

• The foam would initially expand and fill the cavity.
• Then, as it cured and aged, it would shrink significantly, pulling away from the studs and sheathing.
• This left gaps in the wall, allowing air to leak through and defeating the purpose of insulating in the first place.

Eventually, this led to major reliability issues. The industry pulled back, and many manufacturers stepped away from injection foam altogether for quite a while.

The Modern Foam Is Completely Different

Thankfully, building science didn’t stop in the ‘80s. Over the years, injection foam technology was completely reformulated and improved. Today’s products—like the ones we use at Indiana Spray Foam—are engineered to be highly stable, low-shrink, and long-lasting.

The modern version of injection foam has:

• Only about 2% shrinkage, and that happens within the first few hours as the foam fully cures.
• No long-term shrinking or deterioration in the wall cavity once installed.
• A flexible, open-cell structure that allows it to adjust slightly to environmental changes without pulling away from surfaces.

We’ve been installing this type of foam for years, and we’ve never had to return to a job because of foam shrinkage. When properly installed, it performs as expected—and continues doing so for the life of your home.

What Makes Today’s Foam So Reliable?

Modern injection foam is designed for retrofitting, meaning it’s tailored specifically for closed wall cavities that may already contain fiberglass batts or cellulose. It has a unique formula that allows it to:

• Flow easily into every corner and gap,
• Compact old insulation as it fills the cavity,
• And set up quickly and consistently, forming a reliable thermal and air barrier.

It behaves more like a thick, frothy liquid—similar to shaving cream—rather than an aggressively expanding spray foam used in new construction.

By the time we finish a job and put the siding back on, the foam has already reached its stable state and won’t shrink any further.

Why This Matters for Homeowners

When you choose to retrofit your home with injection foam, you’re making an investment in:

• Improved comfort year-round,
• Lower energy bills, and
• Better air sealing, which reduces drafts, allergens, and outside noise.

Knowing that your insulation won’t degrade or shrink over time gives you peace of mind that your investment will last. It’s a big step up from the insulation methods used in homes built before the energy efficiency era.

So if you’re holding off because of something you heard about foam shrinking—rest easy. That’s a thing of the past.

Final Thoughts

We understand why people are cautious about insulation—they want to know it’s going to work not just today, but for years to come. At Indiana Spray Foam, we believe in honest answers backed by real-world results.

Yes, there was a time when foam shrinkage was a real issue. But that time is long gone. The injection foam we use today is reliable, stable, and built for the long haul.

Got more questions? We’re happy to talk you through the process and help you decide if injection foam is right for your home.