As the old adage goes, there’s more than one way to skin a cat. Attic insulation is no different— you have a multitude of options at your disposal. But choosing the right type of attic insulation installation for your home can be the difference between having enough money saved for summer vacation versus losing your summer fund to your energy bill.
Read on for our comprehensive list of the different types of attic insulation, the pros and cons of each, and which one is likeliest to keep your thermostat on an even keel.
What We Talk About When We Talk About Attic Insulation
Before you can go about comparing the many types of attic insulation, it’s essential to understand some of the lingo associated with insulation material.
The overall goal of adding insulation to your attic space is to trap heat and keep it from exiting your building. A material’s effectiveness in achieving that goal is referred to as its R-Value.
The R-Value insulation that your attic should maintain depends on where you live and what the climate is like. Hot climates call for an R30, cold climates command an R49, and moderate climates like may settle near the middle.
The Usual Suspects
Over the years, some forms of attic insulation have become more popular with homeowners due to myriad factors like R-Value, accessibility, durability, eco-friendliness and the ever-important estimation of “bang for your buck.”
Some of these go-to types of attic insulation include:
By far, the most frequently purchased type of attic insulation material is fiberglass, extremely delicate glass fibers that are comprised of recycled material and sand and look uncannily like cotton candy. The most common form that fiberglass insulation takes is in batts, large rolled-up sheets that are held together by an adhesive vapor barrier like reflective foil backing or paper.
Advantages of Fiberglass Batts
Fiberglass batts present some advantages, especially for new construction with attics that don’t have any prior insulation installed (as well as gut renovations). The upside for choosing fiberglass batts includes:
- Moisture Resistance – Though fiberglass isn’t impervious to water, it does tend to resist moisture effectively. This makes it less vulnerable to the growth of mold and mildew.
- Fire Resistance – Fiberglass is noncombustible, so you can rest easy if you have to install it next to your attic’s wooden structure.
- Easy Installation – Batts are easy to pick up and unfurl. And due to their size, they can cover a lot of real estate in a pinch. This makes them a prime candidate for new construction as long as they are installed properly.
Other Types of Batts
For several decades now, fiberglass has reigned supreme as the top-selling insulation batt. But the following variety of batts have also been popular over the years:
- Mineral Wool – Mineral wool is a natural fire barrier, so it would take a fire of 1,800 degrees Fahrenheit to make it burn. And it can continue to insulate even when it’s soaking wet. Mineral wool also makes a great sound blocker but unfortunately, it has been declining in traction and is very scarce these days.
- Denim Insulation – Denim insulation is composed of—are you ready for a tidbit you weren’t expecting?—recycled blue jeans! It’s possible that the very pants you used to feature in your fashion rotation are now boosting your attic insulation.
Denim insulation is becoming a sought-after choice among environmentally conscious consumers because of it’s environmentally friendly material. However, even though it may be popular for that reason, it is extremely expensive.
Blown-in Fiberglass Insulation
Fiberglass also comes in the form of loose-fill insulation, tiny chunks packaged in large bags. These chunks get installed courtesy of a blowing machine that spreads the chunks to fill in necessary spaces.
Though common perception stemming from a 1990’s study was that blown-in fiberglass loses R-value when in temperatures below 20 degrees Fahrenheit, this has since been proven to be false.
Pros and Cons of Blown-in Fiberglass
Taking the blown-in route with fiberglass can be a viable option for several reasons, such as:
- Filling in the Cracks – Contrary to batts, blown-in insulation is perfect for filling in tight voids around wiring, pipes or any area with awkward framing.
- It’s Cheap – You’d be hard-pressed to find a cheaper option than blown-in insulation.
Even though blown-in fiberglass looks different from batts, it’s still the same material, which means it will carry with it the same flaws and potential safety hazards.
The Final Verdict on Blown-in Fiberglass
Blown-in fiberglass insulation may be the right choice for you if your attic fits the following description:
- There’s pre-existing insulation that has left behind gaps
- The joists are spaced irregularly throughout the area
- There are several obstructions on the ground
- There’s a low ceiling. Low-clearance attics aren’t conducive to the maneuvering required for installing batts. But even the
tightest of crawl spaces will still have ample room for a blowing machine to prove effective
Cellulose is made from pieces of newspaper that are shredded into extremely fine pieces. Even though this may seem like a very simple and cost-effective option, cellulose is only positioned this way because of it’s marketing over the years. Blown-in cellulose is probably the worst option for insulation based on more than a few reasons. Here are a few reasons why people think cellulose is a good option (but why it’s really not):
- More Cost-Effective – Despite having a higher R-Value than most fiberglass, cellulose tends to be considerably cheaper. Generally speaking, blown-in cellulose will cost you up to 1/4th less than blown-in fiberglass. Even though cellulose is a very cost-effective option, it’s cheap for a reason…
- Chemical Treatment – Blow-in cellulose manufacturers like to advertise that because cellulose is treated with boric acid, it will repel rodent and insect activity. This is simply not true. The effectiveness of the amount of boric acid that is in cellulose does almost nothing to prevent rodent and insect activity. This is again an act of marketing and has been instilled in customers heads by cellulose manufacturers for many years.
It’s important to note that cellulose is designed to retain water and absorb moisture. This makes it a Valhalla for mold, mildew and potential rotting. To discourage this, all cellulose insulation must be accompanied by a vapor barrier.
The Final Verdict on Blown-in Cellulose
From a usage standpoint, blown-in cellulose can thrive in the same situations as blown-in fiberglass, however, there has been a lot of marketing behind false claims surrounding cellulose that make it a less than preferred option for attic insulation.
As an insulator, nothing tops spray foam. It comes in two varieties—open-cell and closed-cell—the latter of which boasts an unrivaled R-Value of 7! The many distinct advantages of using spray foam insulation include:
- Airtight Seals That Last – When applied, spray foam expands quickly and locks down air in a vault-like seal. And once it’s up, it’s staying. Whereas most insulation material needs to be replaced once every ten years or so, foam can remain at peak performance for several decades. You can essentially set it and forget it.
- No Water Allowed – In the face of moisture, foam is basically anti-cellulose. It’s totally impermeable to water.
- Expanding the Building Envelope – Foam is unique from all other insulation materials in that, when sprayed on your roofline, it has the capacity to expand your building envelope, or the physical space between its conditioned space (i.e. the space that people inhabit) and unconditioned space.
Expanding your building envelope with spray foam also strengthens your building’s structure and even serves as a sound barricade to boot.
From a performance standpoint, one of the main downsides with spray foam is that, in a residential application, it hardens and cannot be removed. If you cover wiring, piping and other obstacles in the attic that then need in a later date some treatment, you will be unable to retrieve them. Apart from that, spray foam is also extremely expensive and thus mostly used in commercial buildings or vaulted ceilings, where you don’t actually have an attic.
The Final Verdict on Spray Foam
There’s no doubt that spray foam is a franchise player. But like top athletes that demand max contracts, the spray can is going to cost you top dollar. And like some athletes, spray foam can be high-maintenance during the installation stage. Unless you’re a professional, it’s extremely difficult to install correctly and safely.
Still, spray foam will block airflow and leakage in an unparalleled fashion that helps you save money on your heating bill like no other insulator on the market. Thus, the higher upfront cost will eventually pay for itself.
While the above represent the most common types of attic insulation, there are other effective alternative methods worth mentioning, such as:
- Rigid Foam Panels – These are panels specifically designed to slow the transfer of heat between studs in your attic’s joists. As their name suggests, they have a rigidity that makes them a breeze to cut to size.
- Radiant Barriers – Although technically not an insulation, if you live in a particularly warm climate, radiant barriers could be the right choice for you. Whereas other insulators work to trap heat inside the home, these barriers are placed on the underside of roofing and padded with reflective material (like aluminum foil) to keep heat away from the house. This can be an excellent way to lower your home’s cooling costs.
At Attic Construction, We’re Here to Help
There are several different routes you can take for installing attic insulation, which unfortunately means there are countless ways to do it incorrectly. Thankfully, Attic Construction is here to help!
As the San Diego area’s #1 provider for both insulation installation and insulation removal, we pride ourselves on working with you and your budget to make the process of insulating your attic hassle-free.
Visit our website to schedule an appointment with one of our expert team members today!
1) “Batts, Blown or Sprayed? What’s the Best Attic Insulation?” by Allison Bailes
2) “Attic Insulation Types” by Rueben Saltzman
3) “Read This Before You Insulate Your Attic” by Mickey Goodman
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