When installing insulation anywhere in your home, it’s vital to understand which direction the facing should go. The facing refers to the paper or foil side of insulation products. Always install the facing toward the heated or air-conditioned part of your home. This creates a vapor barrier that prevents moisture from passing through and getting trapped in the insulation.

Types of Products

The two main types of insulation that use facing are:

Made from melted glass spun into fibers with a paper facing on one side. The facing provides a moisture barrier.

Made from natural materials like basalt or slag. It also has a paper or foil facing to block moisture.

Both fiberglass and mineral wool batts come in faced and unfaced versions. Unfaced products work better for interior walls, while faced products should go on exterior walls, attics, and crawlspaces.

Which Way to Install Facing

When installing faced insulation, the facing should always point toward the interior, heated, or air-conditioned space.

For example:

  • On exterior walls, the facing should touch the drywall.
  • In attics, the facing should point down toward the ceiling below.
  • Under floors, the facing should point up toward the subfloor above.
Danny Lipford installing fiberglass insulation under floor.

The facing paper on the insulation blocks moisture from condensing (changing from a vapor to a liquid) on the insulation. If installed incorrectly, moisture can become trapped between the facing and cause mold, rotting, and reduced R-value. R-value is the measurement of the insulation’s thermal performance.

Vapor Barriers

The facing of the insulation serves as a vapor barrier. Vapor barriers resist moisture penetration, keeping humid interior air from reaching cold surfaces where it could condense. In cold climates, vapor barriers go on the warm side of insulation. In hot, humid climates, they go on the exterior side.

Even with faced insulation appropriately installed, it’s wise to have a separate vapor barrier facing the heated space. This layer adds extra moisture protection. Options for dedicated vapor barriers include:

  • 4–6 millimeter plastic sheeting
  • Kraft-faced fiberglass batts
  • Smart vapor retarder paint
  • Vapor barrier primer

So, Is Proper Facing Direction Crucial for Insulation?

Yes, facing direction is extremely important for insulation installation. Installing the facing incorrectly can lead to trapped moisture, mold growth, material rotting, and reduced insulation effectiveness. Making sure the insulation is installed correctly will maintain your home’s insulation R-value and structural integrity. Don’t cut corners when insulating your home — proper installation is worth the effort.

FAQs About Facing Insulation

Should I staple the facing?

Yes, in most cases. Securely attach the facing to studs or joists with staples so it doesn’t sag or shift. Staples also help create a tight vapor barrier.

Should I compress the insulation?

No. Let the insulation loft to its total thickness without compressing it. Compressing insulation lowers the R-value. Staple the facing tightly without air gaps or puckers.

Can faced insulation cause condensation?

Installed correctly, with the facing toward the interior, faced insulation prevents condensation. Facing that traps moisture inside the insulation by pointing toward the exterior can cause problems.

Should I use both vapor barrier and faced insulation?

Yes, using both together is wise. The facing on insulation acts as a vapor barrier. However, adding a dedicated vapor barrier (like plastic sheeting) on the interior provides extra moisture protection.

What if I install the facing backward?

Reinstall the insulation properly if you notice this mistake. Leaving the facing toward the exterior traps moisture in the insulation, causing mold, rotting, and reduced performance.

Editorial Contributors
avatar for Elisabeth Beauchamp

Elisabeth Beauchamp

Senior Staff Writer

Elisabeth Beauchamp is a content producer for Today’s Homeowner’s Lawn and Windows categories. She graduated from the University of North Carolina at Chapel Hill with degrees in Journalism and Linguistics. When Elisabeth isn’t writing about flowers, foliage, and fertilizer, she’s researching landscaping trends and current events in the agricultural space. Elisabeth aims to educate and equip readers with the tools they need to create a home they love.

Learn More

photo of Casey Daniel

Casey Daniel

Casey Daniel is a writer and editor with a passion for empowering readers to improve their homes and their lives. She has written and reviewed content across multiple topics, including home improvement, lawn and garden care, sustainability, and health and wellness. When she’s not reviewing articles, Casey is usually playing board games, repainting her bathroom, or quilting.

Learn More