The cheapest insulation that still makes a real difference on your energy bills is blown-in fiberglass or cellulose in the attic, done together with air sealing. Per square foot, fiberglass batts and plain EPS foam board are the cheapest materials. But the attic gives the biggest return, because it’s easy to reach and it’s where a lot of your heat escapes. Sealing the air leaks first costs very little and makes every dollar of insulation work harder.
“Cheapest” can mean two things, though. There’s the lowest price on the bag, and there’s the lowest cost for the savings you get. Our Grizzly Insulation Co team helps Denver homeowners on tight budgets every week, so here’s how to get the most comfort for the least money.
What Is the Cheapest Type of Insulation per Square Foot?
Fiberglass batts, blown-in fiberglass, blown cellulose and plain EPS foam board sit at the low end. Cost guides like Fixr put their installed or material costs in roughly these ranges:
Insulation type
Typical cost per square foot
Rigid foam board (polystyrene)
About $0.25 to $2.00
Fiberglass or mineral wool batts
About $0.30 to $2.10
Blown fiberglass or cellulose
About $0.50 to $2.30
Spray foam
About $1.00 to $4.50
Prices swing a lot by thickness, access and region, so treat these as rough guides. Spray foam costs the most up front but seals air leaks at the same time.
What Is the Cheapest Way to Lower Your Energy Bills With Insulation?
Air seal first, then insulate the attic. This isn’t a hunch. ENERGY STAR says homeowners can save an average of 15% on heating and cooling costs by air sealing and adding insulation in attics, floors over crawl spaces and basements. That’s about 11% of total energy costs.
Notice the order in that advice. Air sealing comes first because a leaky ceiling lets warm air blow straight through insulation. Our blog on what air sealing an attic involves shows where the leaks hide.
Is Air Sealing Cheaper Than Adding Insulation?
Usually, yes. The materials are cheap. Caulk, canned foam, weatherstripping and foam outlet gaskets cost a few dollars each. The big leaks are often in a handful of spots:
Around recessed lights, bath fans and plumbing pipes in the ceiling.
The attic hatch or pull-down stairs.
The rim joist where the house sits on the foundation.
Outlets and switches on outside walls.
Gaps around windows and doors.
A weekend with a caulk gun can make a noticeable difference. Bigger jobs, like sealing a whole attic floor, are where an air sealing service earns its keep.
Why Is Attic Insulation the Best Value Upgrade?
Because it’s easy to reach and easy to add to. You don’t have to open any walls. A crew can blow fiberglass or cellulose across an attic floor in a few hours, right on top of whatever’s there now, as long as it’s dry and clean.
Many Denver homes still have attics with just a few inches of old insulation, far below the R-49 to R-60 range recommended for our climate. Topping that up is one of the cheapest big upgrades you can make. Our guide to a poorly insulated attic shows the signs, and our blown-in insulation service does the work.
Is Blown-In Fiberglass or Cellulose Cheaper for Attics?
They’re close in price, and both are good budget choices. Cellulose is made mostly from recycled paper and is a little denser, so it slows air movement a bit more. Blown fiberglass doesn’t absorb water the same way and won’t settle as much over time.
They can be, in the right spot. Fiberglass batts are cheap, sold everywhere and easy to cut. They work well in open walls, floors over crawl spaces and basement rim areas when they’re fitted snugly.
They’re a poor fit for attics with lots of wires, pipes and odd shapes, where gaps are hard to avoid. A badly fitted batt can lose a big share of its R-value. Our guide to batt insulation explains how to install them so they actually work.
Is the Cheapest Insulation Always Worth Buying?
No. You’ll see foil bubble wrap and thin “radiant” products sold as cheap insulation with big savings claims. Some ads suggest a quarter-inch roll can match inches of regular insulation. Nobody has shown that for a typical cold-climate home. Those numbers usually come from ideal lab setups with perfect air gaps.
If your budget were ours, we’d skip the miracle products and spend in this order. Air seal the attic floor, top up the attic with blown-in insulation, seal the rim joists, then look at walls and floors. That order gets the most comfort per dollar in nearly every Denver house we see.
What Are the Cheapest DIY Fixes for Drafty Windows and Doors?
Most cost only a few dollars each and take minutes to install. The easy wins:
Door sweeps on the bottom of outside doors.
New weatherstripping around door frames where the old strip is cracked or flattened.
Window insulation film kits on single-pane or drafty windows for the winter.
Rope caulk on old window frames you don’t open in winter.
These won’t replace attic insulation, but they stop the drafts you can feel. They’re also renter-friendly, since most of them peel off in the spring.
Which Cheap Insulation Fixes Pay Back the Fastest?
The small ones near the top of the list. Here’s roughly how we’d rank them:
Weatherstripping the attic hatch and adding a foam board cover on top.
Sealing big ceiling leaks around lights, fans and pipes.
Blowing in attic insulation to R-49 or more.
Sealing and insulating rim joists in the basement or crawl space.
Foam gaskets behind outlet covers on outside walls.
Each one is cheap on its own. Together, they can change how your house feels on a cold night. Our checklist of signs of poor insulation in a house helps you decide where to start.
What Is the Cheapest Insulation for a Basement or Crawl Space?
Start with the rim joist, the wooden band that sits on top of the foundation. It’s often bare, and it leaks a surprising amount of cold air. Cut pieces of foam board, sealed around the edges with canned foam, are a cheap DIY fix. Closed cell spray foam does it faster and better but costs more.
For the walls, foam board against the concrete is usually the budget pick. Fiberglass batts pressed against bare concrete tend to trap moisture, so they’re a poor choice there. Under a floor over a crawl space, unfaced batts held up with wire supports are the low-cost option, as long as the crawl space stays dry.
If the crawl space is damp or has a dirt floor, fix that first with a vapor barrier. Our crawl space insulation team handles both the moisture and the insulation, so you don’t pay twice.
Are There Rebates That Make Insulation Cheaper?
Yes, often. Xcel Energy runs rebate programs for insulation and air sealing in Colorado, and federal tax credits have also covered insulation and air sealing materials for many homeowners. Those programs change, so check the current rules before you buy. Our blog on the new insulation tax credit explains what to look for.
Does Cheap Insulation Work in Denver's Climate?
Yes, as long as it’s installed well. Our cold winters and big day-to-night swings make air sealing especially valuable. Warm air leaking out of a Denver attic on a 10-degree night carries a lot of heat with it. Cheap materials do fine when they’re sealed and fitted right. Expensive ones fail when they aren’t.
Conclusion
The cheapest insulation isn’t the cheapest bag. It’s the one that saves the most for what you spend. For most homes that means air sealing plus blown-in attic insulation, followed by rim joists and walls. Start there, claim any rebates, and you’ll feel the difference fast. See types of attic insulation to compare your options.
Want the most comfort for your budget? Grizzly Insulation Co can tell you where to start in your Denver home. We’re BPI Certified and an Xcel Energy rebate partner.
Call (303) 854-6221 for an honest quote, or check out our attic insulation services.
Which Insulation Is Cheapest and Still Lowers Your Energy Bills the Most
The cheapest insulation that still makes a real difference on your energy bills is blown-in fiberglass or cellulose in the attic, done together with air sealing. Per square foot, fiberglass batts and plain EPS foam board are the cheapest materials. But the attic gives the biggest return, because it’s easy to reach and it’s where a lot of your heat escapes. Sealing the air leaks first costs very little and makes every dollar of insulation work harder.
“Cheapest” can mean two things, though. There’s the lowest price on the bag, and there’s the lowest cost for the savings you get. Our Grizzly Insulation Co team helps Denver homeowners on tight budgets every week, so here’s how to get the most comfort for the least money.
What Is the Cheapest Type of Insulation per Square Foot?
Fiberglass batts, blown-in fiberglass, blown cellulose and plain EPS foam board sit at the low end. Cost guides like Fixr put their installed or material costs in roughly these ranges:
Prices swing a lot by thickness, access and region, so treat these as rough guides. Spray foam costs the most up front but seals air leaks at the same time.
What Is the Cheapest Way to Lower Your Energy Bills With Insulation?
Air seal first, then insulate the attic. This isn’t a hunch. ENERGY STAR says homeowners can save an average of 15% on heating and cooling costs by air sealing and adding insulation in attics, floors over crawl spaces and basements. That’s about 11% of total energy costs.
Notice the order in that advice. Air sealing comes first because a leaky ceiling lets warm air blow straight through insulation. Our blog on what air sealing an attic involves shows where the leaks hide.
Is Air Sealing Cheaper Than Adding Insulation?
Usually, yes. The materials are cheap. Caulk, canned foam, weatherstripping and foam outlet gaskets cost a few dollars each. The big leaks are often in a handful of spots:
A weekend with a caulk gun can make a noticeable difference. Bigger jobs, like sealing a whole attic floor, are where an air sealing service earns its keep.
Why Is Attic Insulation the Best Value Upgrade?
Because it’s easy to reach and easy to add to. You don’t have to open any walls. A crew can blow fiberglass or cellulose across an attic floor in a few hours, right on top of whatever’s there now, as long as it’s dry and clean.
Many Denver homes still have attics with just a few inches of old insulation, far below the R-49 to R-60 range recommended for our climate. Topping that up is one of the cheapest big upgrades you can make. Our guide to a poorly insulated attic shows the signs, and our blown-in insulation service does the work.
Is Blown-In Fiberglass or Cellulose Cheaper for Attics?
They’re close in price, and both are good budget choices. Cellulose is made mostly from recycled paper and is a little denser, so it slows air movement a bit more. Blown fiberglass doesn’t absorb water the same way and won’t settle as much over time.
Pick based on your attic, not just the price. Our guides on blown fiberglass insulation and the pros and cons of cellulose insulation compare them side by side.
Are Cheap Batts a Good Choice for DIY Insulation?
They can be, in the right spot. Fiberglass batts are cheap, sold everywhere and easy to cut. They work well in open walls, floors over crawl spaces and basement rim areas when they’re fitted snugly.
They’re a poor fit for attics with lots of wires, pipes and odd shapes, where gaps are hard to avoid. A badly fitted batt can lose a big share of its R-value. Our guide to batt insulation explains how to install them so they actually work.
Is the Cheapest Insulation Always Worth Buying?
No. You’ll see foil bubble wrap and thin “radiant” products sold as cheap insulation with big savings claims. Some ads suggest a quarter-inch roll can match inches of regular insulation. Nobody has shown that for a typical cold-climate home. Those numbers usually come from ideal lab setups with perfect air gaps.
If your budget were ours, we’d skip the miracle products and spend in this order. Air seal the attic floor, top up the attic with blown-in insulation, seal the rim joists, then look at walls and floors. That order gets the most comfort per dollar in nearly every Denver house we see.
What Are the Cheapest DIY Fixes for Drafty Windows and Doors?
Most cost only a few dollars each and take minutes to install. The easy wins:
These won’t replace attic insulation, but they stop the drafts you can feel. They’re also renter-friendly, since most of them peel off in the spring.
Which Cheap Insulation Fixes Pay Back the Fastest?
The small ones near the top of the list. Here’s roughly how we’d rank them:
Each one is cheap on its own. Together, they can change how your house feels on a cold night. Our checklist of signs of poor insulation in a house helps you decide where to start.
What Is the Cheapest Insulation for a Basement or Crawl Space?
Start with the rim joist, the wooden band that sits on top of the foundation. It’s often bare, and it leaks a surprising amount of cold air. Cut pieces of foam board, sealed around the edges with canned foam, are a cheap DIY fix. Closed cell spray foam does it faster and better but costs more.
For the walls, foam board against the concrete is usually the budget pick. Fiberglass batts pressed against bare concrete tend to trap moisture, so they’re a poor choice there. Under a floor over a crawl space, unfaced batts held up with wire supports are the low-cost option, as long as the crawl space stays dry.
If the crawl space is damp or has a dirt floor, fix that first with a vapor barrier. Our crawl space insulation team handles both the moisture and the insulation, so you don’t pay twice.
Are There Rebates That Make Insulation Cheaper?
Yes, often. Xcel Energy runs rebate programs for insulation and air sealing in Colorado, and federal tax credits have also covered insulation and air sealing materials for many homeowners. Those programs change, so check the current rules before you buy. Our blog on the new insulation tax credit explains what to look for.
Does Cheap Insulation Work in Denver's Climate?
Yes, as long as it’s installed well. Our cold winters and big day-to-night swings make air sealing especially valuable. Warm air leaking out of a Denver attic on a 10-degree night carries a lot of heat with it. Cheap materials do fine when they’re sealed and fitted right. Expensive ones fail when they aren’t.
Conclusion
The cheapest insulation isn’t the cheapest bag. It’s the one that saves the most for what you spend. For most homes that means air sealing plus blown-in attic insulation, followed by rim joists and walls. Start there, claim any rebates, and you’ll feel the difference fast. See types of attic insulation to compare your options.
Want the most comfort for your budget? Grizzly Insulation Co can tell you where to start in your Denver home. We’re BPI Certified and an Xcel Energy rebate partner.
Call (303) 854-6221 for an honest quote, or check out our attic insulation services.
Frequently Asked Questions
Blown-in fiberglass or cellulose, especially when added on top of existing dry insulation.
Fiberglass batts in open walls. In closed walls, dense-pack cellulose is usually the most affordable.
Materials are cheaper, but mistakes can cost you the savings. Air sealing small leaks is a good DIY job.
Yes, when paired with air sealing. ENERGY STAR estimates about 15% savings on heating and cooling.
Usually not on its own in a cold climate.