How Much Insulation Do I Need in Connecticut? (R-Values Explained)
Let’s cut to the chase: if your house is drafty in the winter and sticky in the summer, it probably doesn’t have enough insulation—or the right kind. A lot of folks think insulation is just fluff in the attic. It’s not. It’s your home’s armor against brutal New England winters, swampy summers, and soul-crushing energy bills.
The key to getting insulation right in Connecticut? Understanding R-value.
Let’s break it down like a contractor who actually works on houses (not just writes blogs about them).
What Is R-Value and Why Should You Care?
R-value measures how well insulation resists heat flow. The higher the number, the better the material is at slowing down the escape of warm air in winter—or blocking the summer heat from creeping in.
Think of R-value like SPF, but for your house. The higher it is, the more protection you’re getting. And in Connecticut, where February feels like a freezer and July hits like a sauna, that protection isn’t optional—it’s essential.
Skimping on R-value is like leaving your front door cracked open with the heat running. Your HVAC system works overtime, your energy bills climb, and your comfort? Out the window.
Want to know if your home’s insulation is actually doing its job? We built a quick R-Value Calculator that takes the guesswork out.
How to Know If Your Home Is Under-Insulated
Most Connecticut homes—especially anything built before 1990—are running on insulation that’s either too thin, poorly installed, or downright expired. So how do you know if your house is one of them?
Here’s what to look for:
Drafty Rooms or Cold Floors
Feel that chill around your feet in the morning? That’s not just “old house charm.” It’s heat slipping out through your floors, walls, or attic. If you find yourself hovering near space heaters or wearing socks year-round, your insulation probably isn’t cutting it.
Uneven Temperatures Between Rooms
If the guest bedroom is an icebox while the kitchen feels like a sauna, your home’s thermal envelope is broken. That usually means your insulation is patchy or missing in key areas—especially attics, knee walls, and crawl spaces.
Higher-Than-Expected Energy Bills
Heating and cooling should feel expensive, but not that expensive. If your bills are creeping up every year with no real changes to your usage, poor insulation might be why. Your HVAC is running longer just to keep up with the heat loss.
Ice Dams on the Roof
This is the big one. If your roof forms icicles or ice dams after a snowstorm, your attic is leaking heat. That melted snow refreezes at the edges, causing backups, roof damage, and in some cases—interior leaks. This is a dead giveaway that your attic insulation (and ventilation) needs help.
Cold Interior Walls in Winter
Touch your interior walls. If they feel cold to the touch, that means they’re not doing a great job of keeping warm air in—or cold air out.
How Much Insulation Do Connecticut Homes Need?
Connecticut sits in Climate Zone 5 (translation: cold enough that you need solid insulation, but not quite Alaska).
Here’s what the pros—and the U.S. Department of Energy—recommend:
If your current insulation doesn’t hit these numbers, you’re probably heating the great outdoors.
Coastal vs. Inland: Region-Specific Insulation Tips for Connecticut Homes
Connecticut may be a small state, but when it comes to insulation, where you live makes a big difference. A shoreline bungalow in Old Saybrook faces a whole different set of challenges than a ranch in Glastonbury or a colonial in Avon. And after nearly 50 years of crawling through homes all over the state, we’ve seen the patterns up close.
If You’re Near the Coast (Old Lyme, Clinton, Westbrook, etc.)
Your main enemies: Humidity, salt air, older framing, and wind-driven moisture.
- Why it matters: Many shoreline homes were built before modern energy codes—and often with minimal wall insulation, no air barrier, and plenty of air gaps. Add in coastal storms and damp summers, and you’ve got a recipe for mold, rot, and rising energy bills.
- Insulation tips:
- Use materials that resist moisture—like dense-pack cellulose, rigid foam, or closed-cell spray foam.
- Make sure you air seal before insulating. Gaps let that humid air sneak into the walls and attic.
- Don’t forget the crawl space. Most shoreline homes sit on piers or shallow foundations that suck in damp air like a sponge.
If You’re Inland (Middletown, Tolland, Cheshire, etc.)
Your main enemies: Cold winters, aging batt insulation, and inconsistent air sealing.
- Why it matters: Homes built in the '80s and '90s inland often look well-insulated—but what’s in those walls is typically fiberglass batts that have settled, sagged, or were never properly fitted in the first place.
- Insulation tips:
- Revisit the attic first—many homes only have R-30 when they need R-49 or more.
- Dense-pack the walls if you’ve got drafty rooms or uneven temps.
- If your basement walls are exposed or uninsulated, add rigid foam or spray foam to cut heat loss and dampness.
Insulation Types and Their R-Values (Per Inch)
Not all insulation is created equal—and neither is its R-value per inch. Some materials give you more thermal resistance with less thickness. Others are more budget-friendly, easier to install, or better at filling gaps. The best choice depends on where you’re insulating, your goals, and your budget.
Let’s break it down:
What “R-Value Per Inch” Actually Means
It’s exactly what it sounds like: how much thermal resistance you get from a single inch of insulation material. The higher the R-value per inch, the less material you need to hit your target R-value. That matters big time in tight spaces like walls or crawl spaces, where every inch counts.
Insulation Comparison Chart (R-Value Per Inch)
Which One Should You Use?
- Tight attic? Go cellulose or spray foam.
- Exposed basement walls? Rigid foam or closed-cell spray foam.
- Old wall cavities? Dense-packed cellulose is your best friend.
- Crawl space that smells like a swamp? Closed-cell spray foam. No contest.
Can Attic Insulation Save You Money?
Insulating the right parts of your home can cut heating and cooling costs by 15–25%—and sometimes more if your home was seriously under-insulated. In Connecticut, that can mean $400 to $800 in annual energy savings for the average homeowner.
Here’s what that looks like over time:
- Attic top-off: Often pays for itself in 3–5 years.
- Wall insulation: 5–8 years, plus big gains in comfort and quieter rooms.
- Crawl space work: 4–6 years, especially if you’re dealing with moisture or cold floors.
And the bonus? Unlike a new fridge or HVAC unit, insulation doesn’t wear out—done right, it lasts 20–30 years.
Ready to Stop Guessing and Start Saving?
If you've made it this far, here's the bottom line: insulation isn't a luxury—it's a necessity. And in a state like Connecticut, where temps swing from Arctic to swampy, getting your R-values right isn’t just about comfort. It’s about protecting your home, cutting your energy bills, and finally putting an end to that draft you’ve been ignoring for years.
Whether you live by the water or up in the hills, there’s no one-size-fits-all fix. But there is a smarter way to figure out what your home needs—and it starts with knowing where you stand.
👉 Use our R-Value Calculator to see if your insulation is doing its job—or costing you money every single month.
Or skip the homework and schedule a free consultation. We’ll take a look, shoot you straight, and help you get your home sealed, insulated, and running like it should. No pressure. Just honest, local work done right.
Common FAQ's about Insulation in Connecticut
How do I know what type of insulation is already in my home?
You can identify your home’s insulation type by inspecting areas like the attic or basement. Fiberglass appears as pink or yellow batts, cellulose looks like loose gray paper, and spray foam is white or yellow and rigid. For certainty, a professional inspection can quickly confirm the material.
Will adding insulation make my home too airtight?
Adding insulation will not make your home too airtight. Most Connecticut homes are under-sealed, not over-sealed. Proper insulation paired with controlled ventilation improves efficiency and comfort. In full retrofits, mechanical ventilation may be added to maintain healthy indoor air quality.
Can I insulate over old insulation, or does it need to be removed?
You can insulate over old insulation if it's dry, clean, and not compressed. However, if the existing material is damp, moldy, or infested, it should be removed first. Professional inspection determines whether to add or replace, ensuring optimal performance and indoor air quality.
How long does insulation installation usually take?
Insulation installation usually takes 1–2 days. Simple jobs like attic top-offs or rim joist spray foam often finish in a few hours. Wall or crawl space insulation may take longer depending on size, accessibility, and whether removal or air sealing is also required.
Is insulation a good investment if I plan to sell my home soon?
Yes, insulation is a good investment if you plan to sell your home soon. It improves energy efficiency, increases resale value, and appeals to buyers looking for lower utility costs. Homes with upgraded insulation often sell faster and at higher prices, while you benefit from comfort and savings in the meantime.
Related Articles
What Is the Best Attic Insulation?
Let’s get one thing straight—there’s no universal “best attic insulation” for every home. That’s like asking what the best pair of shoes is without knowing if you’re running a marathon or going to a wedding. The right insulation depends on your attic, your climate, your budget, and—frankly—how long you plan on sticking around.
Let’s get one thing straight—there’s no universal “best attic insulation” for every home. That’s like asking what the best pair of shoes is without knowing if you’re running a marathon or going to a wedding. The right insulation depends on your attic, your climate, your budget, and—frankly—how long you plan on sticking around.
But here's what we can say: the attic is one of the biggest culprits when it comes to energy loss. Heat loves to rise, and without proper insulation up top, your home is basically wearing a winter coat with no hat. That means higher energy bills, drafty rooms, and HVAC systems working harder than they should.
In this guide, we’ll break down the most popular attic insulation materials—fiberglass, cellulose, spray foam, mineral wool—compare their strengths, costs, and R-values, and help you figure out what’s actually worth your money in 2025. Whether you’ve got a new build, a 100-year-old shoreline cape, or just a suspicion your attic's slacking off, this post is for you.
Let’s dig into what makes insulation great—and how to choose the right kind for your home.
What Makes Insulation ‘The Best’ for Your Attic?
Before we start comparing cellulose to spray foam like it’s a heavyweight title fight, let’s set the bar: what actually makes one attic insulation material better than another?
Here’s what we look at when choosing the best attic insulation:
R-Value (Thermal Resistance)
Think of R-value like the “warmth rating” on a sleeping bag. The higher the number, the better it resists heat transfer. In New England, you want an attic R-value between R-49 and R-60, depending on your setup and climate.
Air Sealing
Insulation slows down heat, but air sealing stops the drafts. Spray foam is the gold standard here—it does both. Dense-pack cellulose can help too. Fiberglass? Not so much.
Moisture Resistance
Insulation that soaks up moisture is asking for mold. If your attic lacks proper ventilation or has humidity issues, pick something that holds up—like closed-cell spray foam or mineral wool.
Longevity and Settling
Insulation is a “set it and forget it” kind of job—if it’s installed right. Spray foam holds its shape. Cellulose and fiberglass can settle if installed too lightly. Batt insulation? Depends on who installs it.
Cost vs. Performance
Spray foam has the highest performance—and the highest price. Cellulose hits the sweet spot for cost, coverage, and comfort. Fiberglass is cheap, but often leaves performance on the table.
👉 Bottom line: The “best” insulation is the one that fits your attic’s needs, not just your wallet.
The Main Types of Attic Insulation (Pros, Cons & What to Expect)
There’s no shortage of options, but these five are the ones we see most in Connecticut attics—and each one has its quirks.
Here’s the no-BS breakdown:
Blown-In Fiberglass
Pros: Affordable, quick install, moderate R-value (R-2.2 to R-2.7)
Cons: No air sealing, moisture-sensitive, settles over time
Best for: Open attics with good airflow and low moisture risk
Dense-Pack Cellulose
Pros: High R-value (R-3.2 to R-3.8), air sealing capability, pest/mold/fire resistant, eco-friendly
Cons: Can settle if under-packed, doesn’t like moisture
Best for: Older homes, retrofits, irregular cavities
Spray Foam (Closed Cell)
Pros: Highest R-value (up to R-7), air seals, moisture barrier, long-lasting
Cons: Expensive, must be professionally installed
Best for: Rim joists, vaulted ceilings, hard-to-reach areas
Fiberglass Batts
Pros: Cheap, easy to install (DIY-friendly), decent R-value
Cons: Poor fit = poor performance, no air sealing, vulnerable to compression
Best for: Simple, accessible attics with standard joist spacing
Mineral Wool
Pros: Good R-value (R-4+), fireproof, water-resistant, soundproof
Cons: More expensive than fiberglass, harder to find
Best for: Moisture-prone or fire-rated assemblies
Attic Insulation Comparison Table
Best Attic Insulation for Different Situations
Let’s match the material to the attic:
- Cold Climates: Closed-cell spray foam or dense-pack cellulose. Seal the leaks, then insulate deep.
- Humid Climates: Radiant barrier plus fiberglass or open-cell foam.
- Older Homes: Dense-pack cellulose + foam at rim joists and access points.
- New Construction: Closed-cell spray foam or hybrid (foam + cellulose).
- DIY Projects: Fiberglass batts or rental cellulose blower kits (if you know what you're doing).
Bottom line: Match the insulation to your home—not the other way around.
What R-Value Do You Really Need in Your Attic?
In Connecticut, aim for R-49 to R-60 in your attic. If you already have R-19, you can add to it.
R-Value by Material (Per Inch)
- Blown-in fiberglass: R-2.2 to R-2.7 → ~18-22 inches needed
- Cellulose: R-3.2 to R-3.8 → ~13-15 inches
- Open-cell foam: R-3.5 to R-4.0
- Closed-cell foam: R-6 to R-7
- Mineral wool: R-4 to R-4.2
And don’t forget: Air sealing comes first. Always.
Common Attic Insulation Mistakes (And How to Avoid Them)
Let’s save you the expensive redo:
- Skipping air sealing: Insulation without sealing is like socks in wet shoes—pointless.
- Choosing solely on price: The cheapest option often costs more in the long run.
- Ignoring ventilation: You need airflow, or you’ll end up with mold.
- Reusing old insulation: If it’s saggy, moldy, or mouse-nested—remove the insulation.
- Leaving the hatch uninsulated: Your attic access is a massive weak point. Seal it tight.
So… What’s the Verdict?
If you’re just looking for the straight answer:
- Best all-around: Dense-pack cellulose
- Best performance: Closed-cell spray foam
- Best combo: Foam for air leaks + cellulose for coverage
Common FAQ's about Attic Insulation
How do I know if my attic insulation needs to be replaced?
You should replace attic insulation if it's sagging, wet, moldy, chewed by pests, or over 20–30 years old. Rising energy bills, drafts, or uneven room temperatures are also warning signs. Poor installation, moisture, or critters can shorten insulation life—if it's never been inspected, it's likely due for a checkup.
Can I add new insulation on top of the old stuff?
You can add new insulation over old material if it's dry, mold-free, and not compacted. This method is cost-effective and helps meet attic R-value codes. However, if the old insulation is damp, damaged, or pest-infested, it should be removed first to avoid trapping moisture or odors.
How long does attic insulation typically last?
Attic insulation typically lasts 20–30 years if installed properly and kept dry. Spray foam can last even longer. Moisture, pests, and settling can shorten its lifespan. If you notice uneven temperatures or higher energy bills, it’s smart to have your attic insulation checked every 10–15 years.
Will new attic insulation qualify me for rebates or tax credits?
Yes, new attic insulation can qualify for rebates and tax credits in Connecticut. Programs like EnergizeCT and the federal Inflation Reduction Act offer incentives for energy-efficient upgrades. To qualify, you’ll need proper documentation, including receipts and possibly a home energy assessment, typically submitted by your contractor.
Conclusion: Insulation Is an Investment—Do It Right
Insulation isn’t sexy, but it saves you money, boosts comfort, and protects your home from the elements. Get it right the first time, and you won’t have to think about it again for 30 years.
👉 Want an expert to take a look at your attic? Contact us today. We’ll help you figure out what actually makes sense for your attic—not just what’s on sale.
How Does Blown-In Fiberglass Compare to Spray Foam in Moisture Resistance?
If you’ve ever walked into your basement after a rainy week and caught a whiff of that musty, damp smell—you already know why moisture resistance matters. Insulation isn’t just about keeping warm in the winter or cool in the summer.
If you’ve ever walked into your basement after a rainy week and caught a whiff of that musty, damp smell—you already know why moisture resistance matters. Insulation isn’t just about keeping warm in the winter or cool in the summer. It’s also your home’s first line of defense against hidden water damage, mold, and air quality issues.
That brings us to a common showdown in the insulation world: blown-in fiberglass vs spray foam moisture resistance. Both materials get tossed around as “energy-saving” upgrades, but only one holds its ground when things get wet.
In this post, we’re breaking down how each insulation type performs when moisture enters the picture—whether it’s humid air, condensation, or a good ol’ New England nor’easter working its way through your walls. We’ll compare absorption rates, mold resistance, and where each one works best in a real Connecticut home.
Let’s get into it.
Understanding Moisture Resistance in Insulation
When we talk about moisture resistance in insulation, we mean how well a material handles water—whether from a leaky roof, humid summer air, or condensation inside your walls.
Why does that matter? Because moisture is the silent killer of comfort and efficiency. It soaks into your insulation, wrecks its R-value, invites mold, and can even rot out your framing. If your insulation acts like a sponge, you’re basically paying to heat or cool a pile of mildew.
Good moisture resistance means:
- No soggy insulation dragging down performance
- Less risk of mold and mildew
- Better indoor air quality
- A longer-lasting thermal barrier
Whether you’re insulating an attic in Guilford or a crawl space in Old Saybrook, understanding how different materials deal with moisture can save you a serious headache down the line.
Blown-In Fiberglass: Pros and Cons for Moisture
Blown-in fiberglass is the fluffy white stuff you’ll see in attics or walls—lightweight, quick to install, and relatively affordable. But here’s the catch: it’s not built to handle moisture.
The Moisture Problem
Fiberglass doesn’t exactly invite mold, since it’s not organic. But it does absorb and hold moisture, which creates the perfect damp, musty environment mold loves. Once it gets wet, fiberglass insulation:
- Loses R-value (up to 50%)
- Slumps or settles in cavities
- Traps moisture against wood framing
- Can make your attic or basement smell like a gym bag
We’ve seen it all over Connecticut—moisture issues with fiberglass insulation are common in homes with poor air sealing, roof leaks, or just a little too much summer humidity.
Where It Can Work
To be fair, blown-in fiberglass does just fine in dry, ventilated spaces—think attics with plenty of airflow and no risk of leaks. But in moisture-prone areas, like basements, crawl spaces, or rim joists? It’s not the material you want in your corner.
Spray Foam Insulation: Pros and Cons for Moisture
Now let’s talk spray foam—the tough, no-nonsense cousin of fiberglass. It expands to seal every crack, crevice, and air leak. And when it comes to moisture? Especially closed-cell spray foam? It’s in a different league.
Closed-Cell = Moisture Barrier
Closed-cell spray foam is dense and rigid—and doesn’t absorb water. It acts as its own vapor barrier, meaning it prevents moisture from getting in at all.
That means:
- No soaking, sagging, or slumping
- No mold growing behind the walls
- No hidden condensation issues
- Bonus: it adds structural strength
It’s the go-to choice for wet basements, crawl spaces, rim joists, or any area where moisture is a concern. It’s also ideal for Connecticut’s humid summers and snowy winters.
What About Open-Cell?
Open-cell spray foam is cheaper and more flexible, but it’s not water-resistant. It can absorb moisture, and it won’t block vapor movement the way closed-cell does. Not a great fit for moisture-prone areas.
Does Spray Foam Prevent Condensation?
Yes—closed-cell spray foam can actually help prevent condensation by sealing air leaks and eliminating the cold surfaces where water vapor would otherwise collect.
Head-to-Head Comparison: Fiberglass vs Spray Foam
Here’s how these two stack up side by side:
Bottom line: fiberglass can work if you control the moisture. But spray foam controls it for you.
Choosing the Right Insulation for Moisture-Prone Areas
So how do you actually choose the right insulation? Here’s how we do it in the field:
1. Where’s it going?
- Dry attic? Fiberglass may work just fine.
- Basement, crawl space, or anywhere with moisture risk? Spray foam wins.
2. What’s the climate?
Connecticut throws us heat, humidity, snow, and wind. That means your insulation needs to block moisture and air leaks year-round.
3. What’s the structure like?
Older homes with uneven framing? Weird little rim joists? Spray foam seals tight, even in tough spots where fiberglass fails.
4. What’s your budget—and your risk tolerance?
Fiberglass costs less up front but may need replacing if it gets wet. Spray foam costs more but lasts decades and protects from the start.
Common FAQ's About Fiberglass, Spray Foam and Moisture
Can I mix blown-in fiberglass and spray foam in different areas of my home?
Yes, you can mix blown-in fiberglass and spray foam in different areas of your home. Spray foam works best in damp or draft-prone spaces like rim joists and crawl spaces, while blown-in fiberglass is ideal for open, dry attics. Using both balances performance, air sealing, and cost efficiency.
Will moisture-resistant insulation help with musty smells in my basement?
Yes, moisture-resistant insulation helps reduce musty basement smells by blocking damp air and preventing condensation. Closed-cell spray foam seals rim joists and walls, keeping moisture out. When combined with air sealing and ventilation, it stops mold and mildew that cause odors and creates a drier, fresher space.
How can I tell if my current insulation has moisture damage?
Check for moisture damage in insulation by smelling for musty odors and looking for sagging, clumped, discolored, or moldy material. In fiberglass, moisture causes settling or compression. Rising energy bills or drafts can also signal trouble. Professionals use thermal cameras or moisture meters to confirm hidden damage.
Do I need a vapor barrier if I use spray foam?
You need a vapor barrier only if you're using open-cell spray foam. Closed-cell spray foam acts as its own vapor barrier due to its density and moisture resistance. Open-cell spray foam allows vapor through, so a separate vapor barrier is often required—especially in basements and crawl spaces in Connecticut.
Is moisture-resistant insulation worth the higher cost?
Moisture-resistant insulation is worth the higher cost in damp areas. Closed-cell spray foam offers insulation, air sealing, and vapor protection in one, preventing mold, rot, and future repairs. Though more expensive upfront, it delivers long-term savings, better energy efficiency, and improved indoor air quality—making it a smart investment in moisture-prone zones.
Final Verdict: Which Insulation Handles Moisture Better?
If moisture’s your concern—and let’s face it, it should be—closed-cell spray foam is your best bet. It blocks water, seals air, adds structure, and keeps you comfortable no matter what’s happening outside.
Blown-in fiberglass has its place, but only in dry, predictable environments. In damp or risky areas, it just doesn’t cut it.
Still not sure? Most insulation problems we see come from good intentions—but the wrong material in the wrong place. That’s why it pays to get it right the first time.
👉 Need help figuring out the right insulation for your home? We’ve been insulating Connecticut homes since 1977, and we know what holds up to the elements—and what doesn’t. Let’s talk.
Which Attic Insulation Type Offers the Best Energy Efficiency—and Why?
Let’s get one thing out of the way: insulation isn’t sexy. But you know what is? Lower energy bills, a more comfortable home, and not hearing your HVAC wheeze like it’s running a marathon.
Let’s get one thing out of the way: insulation isn’t sexy. But you know what is? Lower energy bills, a more comfortable home, and not hearing your HVAC wheeze like it’s running a marathon.
If your attic is under-insulated—or insulated with the wrong stuff—you’re basically paying to heat the outdoors. And in Connecticut, where the seasons come in hot and cold (literally), that’s a losing game.
So which attic insulation type actually delivers when it comes to energy efficiency? Let’s break it down.
What Makes Insulation “Energy Efficient,” Anyway?
Let’s get one thing straight: energy-efficient insulation isn’t just about stuffing something fluffy in your attic and hoping for the best. It’s about controlling how heat moves through your home—and more importantly, how to stop it from escaping like a dog that figured out the screen door.
The first thing folks bring up is R-value. That’s the measurement of how well a material resists heat flow. Higher R-value = better insulation performance. But here’s the kicker: R-value alone doesn’t tell the full story.
Imagine wearing a thick winter coat full of holes. That’s high R-value with bad air sealing. Doesn’t matter how “warm” the material is if drafts are whistling right through it. That’s why air sealing is the unsung hero of insulation. A well-sealed attic paired with the right material will keep your home warmer in winter, cooler in summer, and your HVAC system from running a marathon every day.
Another piece people overlook? Moisture control. Insulation that gets damp (looking at you, open fiberglass batts in a leaky attic) won’t perform well for long. And in a Connecticut climate, where humidity swings like a mood on Monday morning, that stuff matters.
So when we talk about energy-efficient insulation, we’re looking for:
- High R-value (per inch, especially in tight attic spaces)
- Strong air sealing (no sneaky drafts)
- Moisture resistance (so performance stays strong over time)
In short, the best insulation for energy efficiency does more than sit there. It seals, insulates, and holds up to weather, time, and the messiness of real life.
Comparing the Main Types of Attic Insulation
Alright, now that we know what actually makes insulation energy efficient, let’s talk about your options. Not all insulation is created equal—and each type brings something different to the table. Some are air-sealing ninjas. Others are more like paper towels: cheap, common, and not great under pressure.
Here’s the plain-English breakdown.
Spray Foam Insulation (Open-Cell & Closed-Cell)
The Cadillac of attic insulation. Spray foam is high-performance and high-budget—and for good reason.
- Closed-cell spray foam has the highest R-value per inch (around R-6 to R-7), acts as an air and vapor barrier, and basically hardens into a weatherproof seal. It’s ideal for tight, irregular spaces or when you need max performance in minimal depth.
- Open-cell spray foam is softer, cheaper, and still seals air leaks—but it absorbs moisture like a sponge, so we don’t recommend it below-grade or in humid Connecticut attics.
Best for: Energy efficiency, homes with weird attic geometry, or when air sealing is non-negotiable
Downside: Expensive, and it’s not a DIY weekend warrior kind of job
Blown-In Cellulose Insulation
The workhorse. Cellulose is recycled newspaper treated with borates (which handle mold, fire, and pests like a bouncer at the door). It’s dense, it fills every nook, and it’s one of our go-to choices in Connecticut homes.
- R-value sits around R-3.5 to R-4 per inch
- Blown in over attic floors or dense-packed into rafter bays, it settles in tight and stops air movement better than fiberglass
- It’s also eco-friendly and cost-effective—without being flimsy
Best for: Retrofitting older homes, topping off existing insulation, and environmentally conscious upgrades
Downside: Needs proper air sealing underneath to shine. Can settle slightly over time if not dense-packed
Fiberglass Batt Insulation
The old standby. You’ve seen fiberglass: pink or yellow rolls shoved between attic joists. It’s cheap and easy to install, which is why it’s everywhere—but that doesn’t mean it’s the most efficient.
- R-value ranges from R-2.9 to R-3.8 per inch
- Doesn’t seal air gaps at all—so unless it’s paired with perfect air sealing, heat escapes right around it
- Works better in open spaces with standard joist spacing and minimal obstacles
Best for: New builds on a budget, wide-open attic spaces
Downside: Gaps, drafts, and poor performance in real-world conditions if not installed carefully
Each of these materials has its place. But if you're chasing real energy efficiency in your attic—especially in the unpredictable climate we get here in Connecticut—you want to pick the one that does more than just check the R-value box. You want something that actually seals, resists moisture, and lasts.
Energy Efficiency Comparison Table: The Good, The Better, and The Drafty
Now that we’ve walked through the big three insulation types, let’s put them head-to-head in a no-fluff comparison. Because at the end of the day, you’re probably asking: “Which one gives me the most bang for my buck?”
Mike’s Take:
- Want top-tier efficiency with the budget to match? Closed-cell spray foam is hard to beat. It insulates and air seals in one shot.
- Want real performance without breaking the bank? Dense-packed cellulose gives great results—especially when paired with proper air sealing.
- Looking at batts or open-cell foam in a Connecticut attic? You might save upfront, but you’ll likely pay it back (and then some) on your energy bills.
Bottom line: The best attic insulation for energy efficiency isn’t just about R-value—it’s about how well it works in real homes, through real winters, with real utility bills on the line.
What’s the Best Attic Insulation for Connecticut Homes?
Let’s narrow it down. Because while charts and specs are nice, you’re not insulating a lab—you’re insulating a house in Connecticut, where winter winds can rattle your windows and summer humidity turns your attic into a sauna.
For Older Connecticut Homes
Most of the houses we work on—especially along the shoreline—are 50+ years old, drafty as a barn, and built long before energy efficiency was a thing. If that sounds like your place, blown-in cellulose is usually the sweet spot.
- It settles into every nook and cranny in your attic floor
- It plays well with uneven framing and weird attic shapes
- When dense-packed, it seals up air leaks surprisingly well—especially when combined with attic air sealing and baffles
It’s also green, affordable, and it won’t attract pests or mold if installed correctly. We've installed it in homes from Branford to Old Saybrook, and it’s made a night-and-day difference.
For Homes with Moisture Concerns or Complex Rooflines
If your attic looks more like a jungle gym of trusses or you’ve had issues with condensation, damp rafters, or ice dams, closed-cell spray foam is the better long-term play.
- It offers both insulation and a vapor barrier
- It locks in heat and blocks moisture from the roof deck down
- It’s pricier, but in the right situation, it can save you thousands in energy loss and roof repairs
Perfect for homes where you're insulating under the roof deck (cathedral ceilings, conditioned attics, etc.) or when you want your attic space within the thermal envelope.
What We Don’t Recommend
- Open-cell spray foam? Skip it in unvented attics here—it absorbs moisture like a sponge and can lead to rot.
- Fiberglass batts? They’re fine in new builds but don’t hold up well in real-world conditions. Gaps, compression, and air leakage are all too common.
So What’s “Best”?
If we’re talking about the best attic insulation for energy efficiency in Connecticut, the real answer is: it depends on your house. But most of the time, it comes down to dense-packed cellulose for cost-effective upgrades, or closed-cell spray foam for max performance in moisture-prone or complex spaces.
Final Verdict: What’s the Most Energy-Efficient Attic Insulation?
If you’ve stuck with me this far, you now know more about attic insulation than most contractors on Facebook Marketplace. So let’s cut to it:
- Want top-tier efficiency with the budget to match? Go with closed-cell spray foam. It insulates, seals, and shrugs off moisture like a champ.
- Want serious performance without torching your wallet? Dense-packed cellulose is the MVP—especially in older, drafty New England homes.
- Looking at fiberglass batts or open-cell foam for your attic? Be cautious. They have their place, but that place isn’t usually in a Connecticut attic.
Remember, the “best” insulation isn’t just about R-value—it’s about how it performs in your home, with your roof, and your climate. That’s why we don’t do cookie-cutter solutions. We do what works.
And what works? Quality materials, smart air sealing, and an installer who knows the difference between cutting corners and doing it right.
👉 Want us to take a look at your attic and lay out the smartest path forward? Contact Nealon Insulation and let’s make your home more efficient, comfortable, and quiet—without the guesswork.
Common Attic Insulation FAQ's
How do I know if my attic is under-insulated?
You can tell your attic is under-insulated if rooms are hard to heat or cool, ice dams form in winter, or the insulation looks thin, patchy, or dusty. Seeing exposed joists is another red flag. In Connecticut, attics should meet R-49 to R-60. A professional audit confirms insulation levels.
Can I mix different types of attic insulation?
You can mix attic insulation types, like adding cellulose over fiberglass, if the existing material is dry, stable, and air sealing is completed first. Mixing requires care—done improperly, it can trap moisture or reduce performance. Consult a pro to ensure compatibility and code compliance.
Does adding attic insulation qualify for any rebates or tax credits?
Yes, adding attic insulation may qualify for rebates or tax credits. In 2025, the federal Energy Efficient Home Improvement Credit offers up to 30% back (up to $1,200) for qualifying upgrades. Connecticut homeowners may also receive additional rebates through Energize CT based on utility provider and income.
How long does attic insulation typically last?
Attic insulation typically lasts 20–30 years if installed properly and kept dry. Cellulose maintains performance well over time, while fiberglass may settle or degrade. Spray foam can last the lifetime of the home if protected from UV exposure and moisture. Longevity depends on material type and environmental conditions.
Will insulating my attic reduce noise too?
Yes, insulating your attic can reduce noise. Dense materials like cellulose and spray foam absorb sound, helping to block outside noise such as rain or reduce indoor noise like HVAC equipment. While thermal performance is the main benefit, attic insulation also improves home acoustics and quietness.
Let's Work Together
Ready to transform your home into an energy-efficient haven? Schedule your free energy assessment today and experience the Nealon difference for yourself.