Faced vs Unfaced Insulation: What’s the Difference?

Let’s talk about faced vs unfaced insulation. What do the terms mean? How are they different? Where should each be used?

Those issues and more are discussed in the guide to faced vs unfaced insulation.

Faced vs Unfaced - Why The Right Kind of Insulation Matters

You’ll get the best return on your insulation investment in terms of lower energy bills and a healthy house if you use the right type for each application.

It is difficult to overstate the importance of insulation in a new home or home renovation. The right kind of insulation installed correctly will create a strong energy rating in a new home, or improve the energy efficiency in the renovation of an existing home. The goal, of course, is to keep your home comfortable in all climates and weather conditions while lowering energy use and cost. Be green – and save some green!

Major benefits of comprehensive and well-considered insulation include decreased energy bills, improved HVAC performance, less interior noise transfer, greater indoor comfort, and environmentally friendly reduction of carbon footprints.

Choosing Faced vs Unfaced Insulation

Adding insulation – and insulation of the right kind for the location and purpose – can be more complicated than it first appears. When is the last time you heard someone say, “It was an easy job, no problems, no issues, no cost overruns, and right on time”? Many complicating factors can come into play, including climate, structure, cost, heat and cooling sources, and more.

In our discussion of faced vs unfaced insulation, questions arise: Should the insulation be faced or unfaced, or should both be used; why does it matter; and what kind of facing should be used?

Here are brief definitions of unfaced and faced insulation, the types of insulation each is used with, and their applications.

Faced Insulation

Faced Insulation

Faced insulation has a layer of material attached to one side. Insulation facing is designed to limit the penetration of moisture and gases from one location to another, usually from outside the house to the interior. In short, it is a fairly effective vapor barrier.

Pro Tip: When installing faced insulation, the facing should be on the side of the living area. More on this later in this article.

That’s the quick explanation. If you like more detail, here it is.

The purpose of insulation facing is to create a vapor barrier. Here’s why that barrier can be important. When moist, warm air meets a colder surface, moisture condenses on the cool surface. Think about the outside of a glass of ice water as you sit outside on a warm, humid day.

When the cool surface is a wall of your home and the warm, moist air is outside, the confluence of cool and moist/warm can leave moisture in your walls.

Insulation facing prevents the moisture-filled air from passing into your home – your living space. Therefore, anywhere moisture could be an issue, use faced insulation. Attics, basements and crawlspaces, exterior walls when no vapor barrier (Tyvek, for example) is in place are locations to use faced insulation. In fact, many contractors suggest using foil faced or Kraft faced insulation even when house wrap is used on the exterior of the home.

When insulation or the framing surrounding it gets wet, several bad things ensue:

1. The insulation won’t stop heat transfer: Batt insulation becomes compressed and almost completely loses its R value when it gets wet

2: Mold happens: That undesirable moisture will likely cause wood rot and mold growth – dangers to your home and to you, your household and pets.

R-value, by the way, is resistance value – how well the insulation slows/resists the transfer of heat from one location to another. We think about insulation being useful in winter, and it is, to keep warm air in our homes. But it is just as important in summer – resisting the penetration of heat into our homes, causing our house to be uncomfortably warm and/or our central air conditioning system or a window AC to work extra hard.

Pro Tip: A secondary benefit of insulation facing is the control of drafts. Insulation facing covers any small gaps or spaces between the installed insulation and the insulated structure. It helps to seal the space, and a well-sealed home is a very important part of an energy efficient home.

Did you Know? Sealing your home from air drafts to the outside in and from the inside out is just as important as the amount of insulation you have in your home. This guide from the US DOE Energy Star program has good insight and tips for making your home more energy efficient. That’s one of the reasons that makes spray foam insulation attractive in these areas.

Faced insulation is most often found with fiberglass and rock wool insulation.

Insulation Facing Materials

Kraft paper is the most common faced insulation. Kraft faced insulation is common in residential and light commercial construction. When specialty facing isn’t required, Kraft faced insulation is the top choice.

Foil faced insulation is typically fiberglass or rock wool. The insulation is covered by a thin layer of aluminum foil or a mylar material. Foil faced insulation works as designed to prevent the movement of moisture, but adds a second protective factor. By reflecting heat back to its source, foil faced insulation prevents radiative heat movement (which is warmth carried by air through the insulated structure.)

Gypsum board and some latex paints also work well together to prevent the migration of moisture through a structure, but are generally used in commercial, institutional, and industrial buildings.

Vinyl faced insulation is very heavy and durable, but also quite expensive, and so is most commonly used in walls and ceilings of industrial, manufacturing, commercial, institutional, governmental, and other large/metal buildings.

Pro Tip: Small air leaks can sabotage 30 to 70 per cent of your insulation efforts! Check for and seal air leaks around plumbing vents, wires, chimneys, interior walls, windows and doors, and exhaust fans. Check under existing insulation for moisture or dust that shows that air from outside the house is infiltrating through the siding and house sheathing. Incense allowed to smoke near windows, electrical outlets and other house penetrations might also reveal drafty air movement. Caulk, expanding foam insulation, and weather stripping seal air leaks inexpensively. Spray foam insulation is ideal for use where there are many potential air gaps to fill.

Where to Use Faced Insulation

Faced insulation is usually used in walls, floors, ceilings, crawl spaces, and other first-time applications. Faced insulation must be installed with the facing toward the living space, e.g., attic faced insulation faces down, crawl space faced insulation faces up.

Kraft paper is produced from wood pulp using the Swiss-invented chemical “Kraft Process,” and is designed for high strength and durability.

The material is environmentally friendly and can be made from various types of wood material including pine, bamboo  and agricultural left-overs such as .

Installing Kraft Faced Insulation: Install it specifically in exterior walls, exterior basement walls, and attic ceilings. Press the insulation into the cavities between wall studs with the paper side facing the installer. The insulation should fit snugly without compression. Use a staple gun to fasten the paper flange around the insulation to the framing when needed to hold it in place.

Pro Tip: In high-moisture environments like bathrooms, Kraft faced insulation may not perform as well as a plastic sheeting vapor barrier. This is because the paper, while resistant to moisture, isn’t waterproof.

Unfaced Insulation

Unfaced Insulation

Unfaced insulation is made of the same materials as faced insulation but without the facing/barrier. Unfaced insulation is most commonly employed in areas where vapor barriers are not necessary, or where separate vapor barriers will be used. Unfaced insulation is also used in attics to increase the amount of insulation.

Did you Know? Depending on where you live, you should have enough attic insulation to achieve an R-value of R-30 to R-60!

Pro Tip: There are other ways to get the vapor-barrier value of insulation facing without using faced insulation. You might find it is a cheaper and more effective solution, though each project must be evaluated on its own merits.

When insulation facing isn’t the preferred option because you want to install a more complete barrier without seams, consider separate vapor barriers (i.e., vapor barriers not attached by the manufacturer as part of the insulation or insulation facing). They may be constructed of plastic sheeting stapled to interior wall studs, or laid on crawl space floors.

Best Uses of Unfaced Insulation

Unfaced insulation is most effective when added to the attic floor where it can be laid over existing insulation, wall studs between the garage and living area or the space between upstairs and downstairs living areas. Unfaced insulation is also the best option for soundproofing interior walls because the facing isn’t needed and the sound-reduction is about the same – so why waste a few bucks on facing when you don’t need it?

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