Insulation 101: What you need to know


Insulation isn’t rocket science, but there’s more to it than simply keeping your home comfortable and your energy bills low. In fact, insulation involves other disciplines such as building science, materials science, and even basic physics to help improve the comfort, health, energy-efficiency, and the durability of your home. 

Fortunately, you don’t need to know all that! But in your quest for the best insulation material, you’ll come across various terms and many questions. Here are the basics of insulation to help you choose the right solution from the start.

How insulation works

Heat naturally flows from warmer to cooler areas of your home, but heat never transfers naturally in the reverse direction – this process is called thermodynamics. Good insulation can help slow heat entering your home in the summer and escaping it in the winter. When installed properly, insulation can significantly improve your overall comfort, making your home an oasis of serenity throughout the lifetime of your building. 

Add insulation to help fix common issues 

  • High energy bills: Proper insulation plays a significant role in your home’s energy efficiency and can make a big difference in your monthly utility bills. The EPA estimates that the average homeowner can save up to 15% on heating and cooling costs by adding insulation in the attic, crawl spaces, and basement.
  • Noisy environment: Insulation also helps create quieter spaces. It can block the sound of your neighbor’s barking dog or help contain the sound of the movie the kids are watching in the next room. CertainTeed OPTIMA® Blow-In Insulation is perfect for reducing noise transfer between rooms. Add it into closed wall cavities for excellent sound control. 
  • Mold or mildew growth: When moisture gets into your wall cavities, it can condense on every surface and create a breeding ground for mold, mildew, and wood rot. Installing a vapor retarder like CertainTeed MemBrain™ Continuous Air Barrier & Smart Vapor Retarder with your insulation can help keep moisture out and provide an air barrier protection that meets the International Energy Conservation Code (IECC). 
  • Air leakage: Air can sneak into and out of your home through the tiniest of gaps. Complement your insulation with CertainTeed CertaSeal INT™ to help prevent air leakage and control airflow issues. CertaSeal will also help you meet IECC requirements for air leakage rates in a home.

Understanding insulation

Now that you have an overview of the benefits of adding insulation to your home, here are some common insulation terms you should know before purchasing insulation materials.

  • Batts: Batts are pre-cut lengths of insulation blanket that fit between rafters, studs, or wall joists. They are made of fiberglass or mineral wool and can be used to insulate attics, ceilings, walls and floors. Fiberglass batts like InsulPure™ deliver exceptional energy-efficiency and thermal performance for a more comfortable and highly-efficient home.
  • Building envelope: The building envelope consists of all the elements that separate the building interior from the exterior. These include the roof, walls, and floor. The envelope, also referred to as a building enclosure, acts as a barrier between the conditioned indoor environment and the unconditioned outdoor environment surrounding the building. A robust building envelope comprises an exterior weather barrier, an air barrier, a thermal barrier, and a vapor control layer to facilitate indoor temperature control. 
  • Faced/unfaced insulation: Faced insulation is manufactured with a vapor retarder or vapor barrier that helps prevent mold and mildew. Check if your building envelope has any requirements regarding non-combustibility. You also want to follow IECC requirements in regard to the level of vapor control required in your climate zone. Common facings include Kraft paper, FSK (Foil Scrim Kraft), or aluminum foil. Unfaced insulation is manufactured with no attached vapor retarder or facing. Spray foam and loose-fill fiberglass are common types of unfaced insulation. While spray foam does not have a facing, it can be installed to a thickness (depending on it’s permeance) and act like a vapor retarder.
  • R-value: R-value is a rating system that measures how well an insulation material resists the flow of heat. The higher the number, the better the material slows the transfer of heat. The recommended minimum R-value for your home depends on the climate zone of where you live. 
  • Kraft: Kraft is a paper facing attached to batt insulation. The facing typically incorporates flanges (flaps of paper) on both edges used for stapling the insulation in place. Kraft-faced insulation is generally rated as a Class II vapor retarder. 
  • Vapor barrier/vapor retarder: Vapor barriers and vapor retarders are designed to slow the movement of moisture through walls, ceilings, and floors. Note that “barrier” is actually a misnomer. “Retarder” is the more accurate term, because most materials have some degree of permeability, meaning some moisture can still get through. Left uncontrolled, moisture can lead to mold and wood rot issues, putting your home and your family at risk.

CertainTeed InsulPure™ fiberglass insulation won’t settle, accumulate moisture, or lose its R-value over time. 

Four types of insulation available for your remodeling project

Remodeling? There are many different types of insulation to choose from. Below are the most popular insulation options for walls built with wood studs in a residential building. 

  1. Fiberglass batt, faced: For exterior walls and interior walls in kitchens, bathrooms, and laundry rooms – anywhere a vapor retarder is appropriate. 
  2. Fiberglass batt, unfaced: For exterior walls when installed in conjunction with a vapor retarder. Separate sheet vapor retarder if required by climate zone and building code like IECC. This type of insulation is also appropriate for interior walls to dampen room-to-room noise. 
  3. Blown-in fiberglass: Blown-in fiberglass can provide higher R-value per inch as compared to fiberglass batts. It easily fills all voids, and it’s ideal for irregular cavities.
  4. Spray polyurethane foam: Commonly called spray foam or SPF, this product provides the highest insulation R-value per inch, expands to seal every crack and void, and is ideal for tough-to-insulate areas like rim joists and crawl spaces.

There is more than one solution when it comes to insulating your home properly; different types of insulation are available to address your home’s needs, improve its thermal and acoustical performance, and enhance its durability. Learn about the full range of insulation products available from CertainTeed. 

Read up on the many benefits of insulation and continue building your knowledge with expert insights.

Not sure where to start? We can help you find a pro!

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