Kraft Faced or Unfaced?

One of the most common questions we are asked is what is the difference between kraft faced and unfaced insulation and which one should you use.  First let me explain the difference between kraft faced and unfaced insulation and then I  will explain some of the most common applications of each.  Kraft faced insulation is manufactured with a paper facing on one side of the insulation.  The paper serves as a vapor barrier and the paper tabs are used to fasten the insulation in place.   Unfaced insulation is fiberglass only and does not have any type of facing attached to it.  Unfaced insulation is used where a vapor barrier is not needed or a separate vapor barrier is used.  This can be confusing so let me give some applications to clear things up.

Unfaced insulation is typically used in the crawl space.  Twine is used to keep the insulation held in place and from falling on the ground.  A vapor barrier is needed in the crawl space and is provided by a layer of plastic sheeting on the ground.

Exterior walls need a vapor barrier to prevent moisture from moving from a heated space (inside your home) to a colder space (outside your home). Where the warmer air meets a colder surface it will condensate and leave moisture in your walls.  The moisture will destroy your walls because it causes the wood to rot and mold to grow.  Kraft faced insulation is made with a paper facing on it that acts as a vapor barrier.  Unfaced insulation can also be used on exterior walls when a vapor barrier is added on the heated side of the wall.  Unfaced batts are made slightly wider (.25 inches)  than kraft faced batts and serve as friction between studs and are held in place without stapling.  A vapor barrier such as plastic sheeting is then stapled to the studs on the inside (heated side) to provide a vapor barrier.  The method of using unfaced batts and adding a vapor barrier is used by many insulation install professionals because the unfaced insulation is cheaper and faster to install.

What about the attic?  The attic space of your home is a bit more complicated and will be addressed in a future post.

5 Responses to “Kraft Faced or Unfaced?”

  1. Daniel March 28, 2013 at 3:10 pm #

    Good information. Very helpful.

  2. James January 10, 2014 at 2:32 am #

    Thanks for the info. Just what I was looking for.

  3. TrailBoss June 10, 2015 at 12:07 pm #

    What about floor insulation? In particular, if I have a vapor barrier on the ground of a wood framed house (shed, actually) and I wanted to use insulation in the floor for warmth in winter and keeping the shed cool in summer (I will have an a/c-heater unit in shed), would I use faced or unfaced batts in the floor? I can imagine faced batts trapping moisture in the insulation (and joists) between itself and the ground vapor barrier. Am I wrong?

  4. prestonk June 10, 2015 at 3:23 pm #

    TrailBoss- you are correct. Use unfaced with a vapor barrier on the ground.

  5. JWMJAM March 25, 2016 at 2:08 am #

    Very helpful! Thank you!

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