Types of Spray Foam Insulation: Choosing the Right Solution for Your Home

Not Sure Which Types of Spray Foam Insulation You Actually Need?

Here's the thing about spray foam insulation - it's not a one-size-fits-all deal. And honestly, that's a good thing.

We've worked with homeowners in Denver who thought all spray foam was the same. They'd call us asking for "the spray foam" like there's only one option sitting on a shelf somewhere. But the reality? There are different types of spray foam insulation, each with its own strengths, and picking the right one makes a real difference in how your home performs.

Your energy bills, your comfort on those freezing January mornings, even how quiet your home feels - it all connects back to this choice. We're going to walk you through the main options, show you where each one works best, and help you figure out what makes sense for your specific situation.

No fluff. Just practical info you can actually use.

What Spray-Foam Insulation Actually Does for Your Home

Let's start with the basics. Spray foam isn't like those pink fiberglass batts you might've seen in your parents' attic.

It starts as two liquid components. When they mix and hit your wall cavity or attic, they react and expand - sometimes up to 100 times their original size. As they expand, they fill every crack, gap, and irregular space. Then they harden into place, creating a seal that's both insulating and airtight.

That's the key difference. Old-school insulation like fiberglass just sits there. It provides some thermal resistance, sure. But air still moves around it, through it, behind it. That's why you get drafts.

Spray foam? It stops air movement completely. Which means:

• No more cold spots near windows or along exterior walls

• Fewer drafts sneaking in through tiny cracks you didn't even know existed

• Better moisture control (especially important in basements and crawl spaces)

• Lower energy bills because your HVAC isn't working overtime

We had a client in Park Hill last year - older home, original windows, constantly running the heat. After we did spray foam in the attic and exterior walls, their January gas bill dropped by about 35%. They called us two months later just to say thanks. That doesn't happen with every insulation job, but it happens enough that we know this stuff works.

The Two Main Types You Need to Know About

Alright, here's where it gets specific. When people talk about spray foam, they're usually referring to one of two types: open-cell or closed-cell.

Both are spray foam. Both expand and seal. But they're built differently, they perform differently, and - yeah - they cost differently too.

Think of it this way: open-cell is like a sponge. Closed-cell is more like a rigid foam cooler. Different structures, different jobs.

The choice between them depends on what part of your home you're insulating, what your budget looks like, and what performance goals you're trying to hit. Some projects call for one, some call for the other, and sometimes (this happens more than you'd think) you use both in different areas of the same house.

Let's break down each one.

Open-Cell Spray Foam: The Budget-Friendly Option

Open-cell foam has a soft, spongy texture once it cures. If you pressed on it with your hand, it'd give a little - not like a rock, more like a firm cushion.

The "open-cell" name comes from its structure. The tiny cells in the foam aren't completely sealed off from each other. Some air can move between them. This makes it lighter and less dense (usually around 0.5 pounds per cubic foot).

R-Value and Performance

You're looking at roughly R-3.5 to R-4 per inch of thickness. That's decent, but it means you need more inches to hit the same insulation value as closed-cell.

Where It Shines

Open-cell is great for sound control. Those partially open cells absorb sound waves really well. If you're insulating between interior walls or trying to quiet down a home office, this is your go-to.

It's also easier on the wallet. Material costs are lower, and because it expands more aggressively, you often use less product to fill a space.

And it's forgiving. Got an oddly shaped cavity or lots of wiring and pipes? Open-cell will flow around obstacles and fill those irregular spaces without much fuss.

The Limitations

Here's where you need to be careful. Open-cell isn't a great vapor barrier. In areas where moisture control is critical - like basements or crawl spaces - it might not be enough on its own. You'd need an additional vapor barrier layer.

It also doesn't add structural strength to your walls the way closed-cell does. And if you're in a really cold climate (which, let's be honest, Denver can be), you'll need a thicker application to meet building code requirements.

Best Use Cases

We install open-cell most often in:

• Interior wall cavities (especially for sound)

• Attics in moderate climates

• Retrofit projects where budget is a concern

• Bonus rooms or converted spaces where you need fast, effective insulation

One of our clients in Highlands Ranch used open-cell in their finished attic. They wanted to turn it into a home gym but it was unbearably hot in summer and freezing in winter. Open-cell brought the temperature in line with the rest of the house, and as a bonus, they stopped hearing every footstep from the kids' rooms below. Two problems solved.

Closed-Cell Spray Foam: The High-Performance Choice

Closed-cell foam is the dense, rigid option. Once it cures, it's hard - almost like plastic. You're not denting this stuff with your hand.

The cells are completely closed off from each other, trapping the blowing agent inside. This gives it a much tighter structure and significantly better insulating power.

R-Value and Performance

Closed-cell delivers around R-6 to R-7 per inch. That's nearly double the insulating value of open-cell in the same thickness. In practical terms, this means you can insulate tighter spaces (like a rim joist area) without losing precious headroom or square footage.

The Big Advantages

Closed-cell is both an air barrier and a vapor barrier. It blocks moisture really well, which makes it ideal for below-grade applications like basements and crawl spaces.

It also adds structural rigidity to your walls. According to some studies, closed-cell spray foam can increase a wall's racking strength by up to 300%. We're not saying it replaces proper framing, but it definitely contributes to overall stability - especially helpful in older homes with settling issues.

And because it's so dense, it holds up in harsh conditions. Moisture, temperature swings, even minor flooding - it keeps performing.

The Trade-Offs

It costs more. Both the material itself and the installation are pricier than open-cell. If you're insulating a large area, that difference adds up quickly.

It's also less forgiving in application. You need experienced installers who know how to work with it properly. (We've seen DIY closed-cell disasters. Not pretty.)

And it doesn't absorb sound as well as open-cell. It blocks sound transmission better than nothing, but if soundproofing is your primary goal, open-cell usually wins.

Where We Use It Most

Closed-cell is our recommendation for:

• Exterior walls in cold climates

• Basements and crawl spaces

• Conditioned attic decks (where the roof deck itself is insulated)

• Rim joists and band joists

• Any area where moisture or vapor control is critical

• High-performance builds or net-zero projects

We did a crawl space job in Denver last winter where the homeowner had been dealing with recurring moisture and cold floors above. Closed-cell completely transformed it. No more damp smell, no more cold floors, and their heating bills dropped noticeably. That's the kind of project where closed-cell really proves its worth.

Side-by-Side: How They Actually Compare

Let's put them next to each other so you can see the differences clearly.

Feature	Open-Cell	Closed-Cell
R-Value per inch	~3.5-4	~6-7
Density	~0.5 lb/ft³	~2 lb/ft³
Vapor barrier?	No (needs additional barrier)	Yes
Air barrier?	Yes	Yes
Sound absorption	Excellent	Good
Structural support	Minimal	Significant
Cost	Lower	Higher
Best for	Interior walls, attics, soundproofing	Exterior walls, basements, moisture-prone areas

When you're deciding, think about these factors:

Budget matters, obviously. If you've got a tight number to hit and you're insulating non-critical areas, open-cell might be the smart call.

Performance goals also matter. Are you trying to meet a specific R-value requirement in a tight space? Closed-cell. Want to kill echo in your home office? Open-cell.

Location in the house is huge. Anything below grade or exposed to exterior conditions? Lean toward closed-cell. Interior spaces that don't face weather? Open-cell is usually fine.

And here's something we tell people all the time: you don't have to pick just one. We've done plenty of homes where we use closed-cell in the basement and rim joists, then switch to open-cell for interior walls and the attic. It's about matching the product to the need.

Which Type Actually Fits Your Home?

This is where it gets personal. Your house isn't like your neighbor's house, and your priorities probably aren't either.

Here's a quick decision-making framework we use with clients:

Climate Zone

Denver sits in a cold climate zone. We see real winters. That means vapor control and high R-values matter more than they would in, say, Arizona. If you're insulating exterior-facing areas, closed-cell usually makes sense.

But if you're working on interior spaces that aren't directly exposed to outside temps, open-cell can absolutely do the job.

Which Part of the Home?

• Attic: Open-cell often works great, especially if it's vented. Closed-cell if you're creating a conditioned attic space.

• Exterior walls: Closed-cell for maximum performance, open-cell if budget is tight.

• Basement/crawl space: Closed-cell, hands down. Moisture control is too important.

• Interior walls: Open-cell for sound and cost savings.

• Rim joists: Closed-cell. Those are major thermal weak points.

  
  

Budget and ROI

Let's be real - closed-cell costs more upfront. Sometimes significantly more. But if you're in a situation where moisture damage is a risk, or where energy bills are eating your budget, that extra cost pays for itself.

We had a client in Wash Park who wanted to go all closed-cell in their 1920s bungalow. After walking through the house and looking at their goals (and budget), we suggested closed-cell for the basement and exterior walls, open-cell in the attic. Saved them about $3,500 and they still got the performance where it mattered most.

Structural Concerns

Older home with some settling or minor structural issues? The rigidity of closed-cell can actually help. We're not structural engineers - definitely get one involved if you have serious concerns - but we've seen closed-cell provide real support in older builds.

Real-World Scenarios

Renovating an older home with questionable moisture history? Go heavy on closed-cell in vulnerable areas.

Building new and trying to hit high energy-efficiency standards? Closed-cell in the envelope, maybe open-cell for interior soundproofing.

Finishing a bonus room above the garage? Open-cell is usually enough and keeps costs reasonable.

The point is: there's no universal answer. It's about matching the foam type to your specific situation. That's why we always start with an evaluation before quoting a project.

Beyond R-Value: The Other Stuff That Matters

R-value gets all the attention (it's how we measure insulation performance), but honestly, there's more to the story.

Comfort and Air Quality

The airtight seal from spray foam - especially closed-cell - eliminates drafts. That means more consistent temperatures from room to room. No more cold spots near windows. No more feeling a breeze when you walk past an outlet.

And better air sealing means fewer allergens, less dust, and less outdoor pollution sneaking into your home. We've had clients tell us their allergy symptoms improved after we sealed up their homes with spray foam. Wasn't even something they were expecting.

Moisture and Mold Resistance

This is especially important in Colorado's climate. We get dry conditions most of the year, but we also get snow, and when that melts, moisture tries to find its way into basements and crawl spaces.

Closed-cell foam creates a moisture barrier that helps prevent mold growth. Mold needs moisture to thrive. Cut off the moisture, and you've solved the problem before it starts.

Sound Control

Open-cell is a game-changer for noise. If you've got a home theater, a music room, or just want your bedroom to be quieter, open-cell in the walls makes a noticeable difference.

We insulated a home office last year for a guy who was on Zoom calls all day. His kids were homeschooled and running around the house constantly. After we did open-cell in his office walls, he said it was like working in a different house. Finally got some peace.

Longevity

Spray foam doesn't sag, settle, or degrade the way fiberglass can. Once it's in, it's in. We're talking decades of performance without needing replacement.

And because it eliminates thermal bridges (those spots where heat escapes through framing), your HVAC system doesn't have to work as hard. Less wear and tear, longer equipment life.

What Installation Actually Involves (And Why DIY Usually Isn't Worth It)

Let's talk about the actual process, because understanding what's involved helps you know what to expect - and why hiring pros is usually the smart move.

The Professional Process

First, we prep the space. That means clearing out debris, checking for moisture issues, making sure all wiring and plumbing is in place (you can't move that stuff after foam is applied).

We mask off anything that shouldn't get foam on it. Windows, outlets, areas you want to keep exposed - it all gets covered.

Then comes safety gear. Full respirator, protective suit, gloves. Spray foam chemicals aren't something you want to mess around with during application.

The actual spraying is where experience really matters. You need the right thickness (not too thin, not too thick), the right coverage (no gaps or voids), and you need to know how different temps and humidity levels affect the foam's expansion.

After application, there's usually a curing period. Then we come back, trim any excess, and clean up. A good contractor will also do a final walkthrough to make sure everything looks right.

Why DIY Kits Are Risky

You can buy small DIY spray foam kits at home improvement stores. They're fine for tiny jobs - sealing a crack here or there, filling a small gap.

But for whole rooms or entire homes? Not recommended. Here's why:

The equipment matters. Professional rigs heat and mix the chemicals at precise ratios. Get it wrong, and the foam doesn't perform the way it should.

You need to know building codes. Thickness requirements, vapor barrier rules, fire safety - it's not intuitive.

And honestly, it's messy. We've been called in to fix DIY jobs more times than I can count. Usually costs more to fix than it would've cost to hire us from the start.

Choosing the Right Installer

Look for certified installers. Ask about their experience with both open-cell and closed-cell.

Check references. Ask about cleanup and whether they handle inspection requirements.

Get a detailed quote that breaks down material type, thickness, area coverage, and warranty terms.

And make sure they're handling ventilation properly. Some spaces need continued ventilation even after spray foam; others don't. A good installer knows the difference.

What It Costs and What You Get Back

Money talk. Let's be straight about it.

Cost Drivers

Several things affect the final price:

• Foam type (closed-cell costs roughly 50-70% more than open-cell)

• Total area you're insulating

• Thickness required to meet your goals

• Access difficulty (crawl spaces are harder to work in than open attics)

• Current condition of the space (if we need to do extensive prep, that adds time)

Typical Ranges

This varies a lot, but as a rough guide: open-cell usually runs around $1.00-$1.50 per board foot. Closed-cell is more like $1.50-$2.50 per board foot. (A board foot is one square foot at one inch thick.)

For a 1,500-square-foot attic with open-cell at 6 inches thick, you're probably looking at $3,000-$5,000. Same space with closed-cell might be $5,000-$8,000.

But here's the thing - you need an actual quote. Every job is different. We don't give ballpark numbers over the phone because we don't want to mislead anyone.

Energy Savings

A properly insulated home can cut heating and cooling costs by 20-40%, according to the Department of Energy. In Denver, where we've got cold winters and warm summers, that adds up fast.

If your gas bill averages $200/month in winter, a 30% reduction means saving $60/month. Over a year, that's $300-$400. Over ten years? You've likely paid for the insulation and then some.

Plus, when you go to sell your home, energy-efficient upgrades are a selling point. Buyers care about lower utility bills.

Long-Term Benefits

Beyond energy savings, think about:

• Fewer HVAC repairs (less strain on the system)

• Less risk of moisture damage (which can be expensive to fix)

• Better comfort (hard to put a price on that, but it matters)

• Durability (spray foam lasts - you're not replacing it in five years)

We're not saying spray foam is cheap. It's not. But when you factor in what you get back over time, the math usually works out in your favor.

Ready to Make the Right Choice?

So here's the recap: open-cell and closed-cell both have their place. Open-cell is lighter on the budget, great for sound, and works well in interior spaces. Closed-cell is the high-performance option for exterior walls, basements, and anywhere moisture control matters.

The "best" choice depends entirely on what you're insulating, what your goals are, and what your budget looks like. Sometimes you use both. Sometimes one makes way more sense than the other.

What matters most is getting the installation done right. Foam type is important, but proper application and thickness matter just as much. Cut corners on installation, and you won't get the performance you're paying for.

Here's What We'd Suggest

Don't guess. Get a professional evaluation before you commit to anything. We'll come out, look at your specific situation, talk through your goals and budget, and give you honest recommendations.

Sometimes that means spray foam. Sometimes it means a hybrid approach. And yeah, sometimes it means a different insulation method altogether. We're here to solve your comfort and energy problems - not just sell one specific product.

Ready to get started?

Schedule a complimentary home-insulation evaluation with Level Up Insulation. We'll walk through your home, answer your questions, and put together a plan that actually makes sense for your situation.

No pressure. No generic sales pitch. Just practical advice from people who've done this thousands of times.

FAQs: Your Spray Foam Questions Answered

How long does spray-foam insulation actually last?

Indefinitely, if installed correctly. We're talking 80+ years. Unlike fiberglass, which can sag and settle over time, spray foam stays put. It doesn't break down, it doesn't lose R-value. Once it's in, you're done.

Can I mix open-cell and closed-cell in the same house?

Absolutely. We do it all the time. Use closed-cell where moisture control and high R-value matter most (basement, exterior walls), then switch to open-cell for interior spaces where sound control and budget are bigger priorities. It's a smart way to optimize performance and cost.

Is spray foam safe in existing homes with electrical and plumbing?

Yes, as long as everything is properly installed and inspected first. We make sure all wiring is secured and all plumbing is in good shape before we spray. Once cured, spray foam is inert - it's not going to damage your systems. Just make sure your installer knows what they're doing.

Will spray foam make my home "too airtight"?

It's a valid concern. Modern building codes require mechanical ventilation in very tight homes (like an ERV or HRV system). We'll tell you if your home needs additional ventilation. The goal is balanced: airtight enough to be efficient, but with controlled fresh air exchange. We've never seen a situation where "too tight" was actually a problem once proper ventilation was addressed.

How thick should spray foam be in Colorado?

Depends on the area and the foam type. For attics, you typically want R-49 to R-60, which means about 12-15 inches of open-cell or 8-10 inches of closed-cell. Exterior walls usually need R-21 to R-25 (around 6 inches of open-cell or 3-4 inches of closed-cell). Basements and crawl spaces vary. We calculate exact thickness during the evaluation based on your specific build and code requirements.

What if I only want to insulate part of my home right now?

That's fine. A lot of people phase their projects. Start with the biggest problem areas - usually the attic or basement - and go from there. We'll help you prioritize based on where you'll see the most impact for your budget.

Does spray foam need maintenance?

Nope. Once it's installed and cured, you're done. No fluffing, no replacing, no checking on it every few years. It just sits there doing its job. That's one of the best things about it.