Kraft-Faced Insulation
Kraft-faced insulation is insulation with a facing of paper vapor retarder that helps to ensure that the insulation stays dry out. Typically, kraft-faced insulation is installed in exterior walls as well as attic ceilings, which are virtually vulnerable to condensation and vapor. Insulation for interior walls tends to be unfaced.
The kraft-paper facing on insulation changes things like fire take chances, toll, in addition to how as well as where the insulation tin can live installed. This all affects the demand for as well as benefits of using it for interior walls.
There are no detail rules against using Kraft-faced insulation on interior walls. But in that location are no detail benefits either, except that Kraft-faced insulation is easier to install.
No Rules Prohibiting Kraft Facing inwards Interior Walls
The International Residential Code (IRC) Section R702.7 comments on vapor retarders in outside walls.
The IRC requires the function of Class I or II vapor retarders inward outside walls inwards common cold climates (zones 5-8 as well as marine zone four). Kraft facing is a Class II vapor retarder, and then it is standard for outside walls inwards colder states.
[REPLACE WITH LICENSED IMAGE: climate zone map]
However, the IRC does not take or prohibit using vapor retarders, like kraft facing, in interior walls.
The fact that the IRC does non say anything nigh this practice reaffirms that it is non harmful to position kraft-faced insulation inward interior walls.
Local codes sometimes differ from the IRC, only I accept found no specific word of kraft-faced insulation (or vapor retarders in full general) inwards interior walls. It is more than probable that local code would differ inward terms of rules about outside walls.
For example, unremarkably, vapor retarders/facing should be installed towards the interior of the outside wall (this is what the IRC stipulates). But some states in hot in addition to humid climates similar the Gulf Coast have local codes that need the vapor retarder to be installed facing the outside.
It all depends on where the condensation is nigh probable to course together with be problematic.
Considerations for This Insulation
Kraft Facing Can Only Be on One Side
If y'all’re using Kraft-faced insulation for its vapor barrier properties because you’re concerned about moisture, it’s of import to retrieve that more than is not e'er amend.
Putting a vapor retarder on both sides of a wall will trap wet within the insulation in addition to wall cavity. A double vapor barrier basically creates a sandwich of soggy insulation amongst impermeable facing on either side.
Insulation will run into moisture ane way or some other—from construction moisture that lingers, from water leaks, or from humidity too condensation. It needs to live able to escape through about sort of permeable cloth.
Condensation tin drive the insulation to get moldy. Moisture besides reduces the R-value of the insulation.
Basically, a wall needs to live able to dry inward ane direction. It either dries towards the exterior (common cold climates) or towards the interior (warm climates).
As Joseph Lstiburek of Building Science Corporation tells us inwards his article “Macbeth Does Vapor Barriers”, recall the phrase “Double, Double, Toil together with Trouble”!
The Paper Is Flammable
Almost all faced insulation is combustible. Paper and plastic facing volition burn too, inwards the example of plastic facing, tin can unloosen fumes spell burning. Fiberglass insulation itself is non combustible, only equally before long every bit y'all add Kraft facing, it causes the whole unit of measurement of insulation summation facing to be classed every bit flammable.
The facing side of faced insulation can never live left exposed. Only flaming-resistant foil (FSK-25) facing tin can live left exposed. In fact, the newspaper itself will be printed amongst a label that says “Do not leave exposed.”
Basically, the kraft facing tells you “If you tin can read this, something is incorrect.”
Even then, yous belike wouldn’t get out kraft facing exposed if you’re using it inward interior walls. Your interior walls would presumably live finished with drywall. Gypsum wallboard (another advert for drywall) is an acceptable fire barrier for insulation.
People are more probable to leave kraft-faced insulation exposed inward an unfinished attic, where it is a fire take a chance.
Turning the paper against the wall satisfies the IRC inwards terms of burn prophylactic. But so there would be no indicate inward installing it. You mightiness too merely purpose un-faced.
It Is More Expensive to Buy Faced Insulation
Faced insulation is slightly more than expensive than unfaced insulation. The toll divergence is because the facing is an extra fabric that sometimes too needs to be treated or tested.
It’sec a pretty child deviation, just we should never discount it, especially for larger areas. Unfaced insulation typically costs most $0.fifty to $one.75 per square foot. Faced insulation typically costs near $0.l to $ii.00 per square pes.
So, the cheapest faced insulation will be similar to the cheapest unfaced insulation. The cost departure comes into play inwards the upper reach of products.
The toll divergence is worth it for exterior walls, specially inward colder climates where you lot’re often required past code to have a vapor barrier on the warm-inwards-winter side of exterior walls.
If yous had extra faced insulation left over, it would not injure to function it inwards interior walls (every bit long every bit the vapor barrier is only on one side). But if you lot are buying insulation specifically for your interior walls, in that location is no particular argue to accept on this additional price.
Benefits of Kraft-Faced Insulation inwards Interior Walls
By far the main argue to use Kraft-faced insulation inwards interior walls is that it’s easier to install. The newspaper facing means that the insulation won’t fall down or sag similar unfaced batts tin make. Additionally, yous tin easily roll and cutting faced insulation.
Most importantly, faced insulation tin be easily stapled to the studs inwards a wall. You won’t take to wrestle alongside looser, less sturdy unfaced batts. So, if y'all’re a DIYer—peculiarly if yous don’t take much insulation experience—it mightiness be worth it to leap for kraft-faced insulation.
It’s worth noting that Kraft-faced insulation is less sound-quieting than unfaced insulation. Still, at that place are ways of compensating for this together with many contractors contend whether exceptional sound-slow insulation is fifty-fifty worth it.
Doubling upwardly on layers of drywall tin oftentimes live but as effective at audio control.
A vapor barrier tin be helpful inward walls betwixt rooms that tin can get humid, such as bathrooms too kitchens. However, it is more common to rely on latex-based primers as well as paints every bit vapor barriers 1n these interior scenarios, instead of using faced insulation to make the vapor barrier.
Sources
https://www.jm.com/en/web log/2019/october/unfaced-vs–kraft-faced-insulation–what-s-the-difference-/
https://www.certainteed.com/insulation/installation-vapor-retarders/
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