Use unfaced insulation whenever you add a layer over insulation that is already in your attic, and in any vented attic where a vapor retarder is not required. Reach for faced (kraft or foil) insulation only on the first layer against a bare attic floor in a cold climate, with the facing pointed down toward the heated living space. The reason is simple: two vapor barriers stacked in one assembly trap moisture between them, and a second faced layer on top of an existing faced layer does exactly that.
Most attic insulation questions come down to that one decision. This guide gives you the rule, the code behind it, and a quick table so you can pick faced or unfaced without guessing. If you are still planning how deep to go, our attic insulation calculator and the insulation R-value chart tell you how much material your climate zone needs.
Faced or unfaced insulation in an attic: the quick rule
Faced insulation carries a paper, foil, or plastic vapor retarder bonded to one side; unfaced insulation is bare batt or blown fiber with no retarder. In an attic, the working rule is one vapor retarder per assembly, on the warm-in-winter side. That means faced goes on the first layer with the facing down, and every layer stacked on top of it is unfaced.
The single most common attic insulation mistake is laying a second faced batt on top of an existing faced batt. The two facings sandwich a pocket of air, moisture condenses between them, and the fiber underneath stays damp. Bare (unfaced) rolls solve this because they let vapor pass straight through to the layer below and out through attic ventilation.
| Attic situation | Use | Why |
|---|---|---|
| Adding a layer over existing insulation (any type) | Unfaced | A second facing creates a double vapor barrier that traps moisture |
| First layer on a bare attic floor, cold climate (IECC zones 5 to 8 and marine 4) | Faced, facing down | Code often requires a Class I or II vapor retarder toward the heated space |
| First layer on a bare floor, hot or mixed climate (zones 1 to 3) | Unfaced | A ceiling vapor retarder is generally not required and can trap moisture in cooling climates |
| Vented attic with 12 inches or more of clearance above insulation | Unfaced | IRC treats the vent space itself as the moisture control, so no retarder is needed |
| Blown-in loose fill (cellulose or fiberglass) | Unfaced (loose fill has no facing) | Loose fill is inherently vapor open; add a separate retarder only if code requires one |
| Unvented (sealed) attic with spray foam at the roof deck | Neither, or unfaced fill | Closed-cell foam is its own vapor control; a batt facing would double it |
Do I need faced insulation in my attic at all?
In most attics you do not need faced insulation, because the attic is either vented or already has a vapor retarder in place. You need a vapor retarder only when the assembly lacks one and your climate zone requires it. A vented attic with adequate ceiling insulation and continuous soffit-to-ridge airflow usually satisfies moisture control without any facing.
The 2021 International Residential Code (IRC), section R806.5, allows an unvented attic assembly only under specific conditions; a standard vented attic is the default. Section R806 also sets the ventilation ratio at 1 square foot of net free vent area per 150 square feet of attic floor, or 1 per 300 when balanced high and low vents are used. When that ventilation is working, the vent space carries moisture out and a ceiling vapor retarder becomes optional in most zones.
The one clear case for faced insulation is a cold-climate attic (IECC zones 5, 6, 7, 8, and marine 4) getting its first and only layer laid directly on a bare ceiling. There, code commonly calls for a Class I or Class II vapor retarder on the interior side, and a faced batt with the kraft toward the living space provides it. To size that first layer correctly, see our guide to attic floor insulation.
Which way does the facing go?
The facing always points toward the warm-in-winter side of the assembly, which in a heated home means the facing faces down toward the living space, not up toward the roof. Vapor moves from warm to cold, so the retarder belongs on the warm face to stop indoor humidity from reaching the cold attic and condensing.
On an attic floor, that puts the kraft or foil in direct contact with the ceiling drywall below, fiber side up. Installing a faced batt upside down, with the paper facing the roof, puts the retarder on the cold side and can trap moisture inside the insulation instead of blocking it. In a cooling-dominated climate the direction question is usually moot, because a ceiling vapor retarder is not recommended there at all.
Unfaced insulation over existing insulation
Always use unfaced insulation when you top up an attic, regardless of what is already down there. Bare batts or loose fill let vapor pass through to the existing layer and out through the vents, so no moisture gets trapped between two barriers. This holds whether the existing layer is faced, unfaced, or blown-in.
- Confirm the existing insulation is dry and not compressed. Damp or moldy insulation should be removed first, not buried.
- Air seal the attic floor before adding anything. Top plates, wire and pipe penetrations, and the attic hatch leak far more heat than a thin insulation layer loses. See our guide to air sealing an attic.
- If the existing batts are faced, do not slit or remove the facing; just lay unfaced material on top.
- Run the new unfaced batts perpendicular (crosswise) to the existing joists or batts to cover the wood framing and cut thermal bridging.
- Keep insulation off recessed lights unless they are IC-rated, and hold it back from soffit vents with baffles so airflow stays open.
Kraft-faced insulation and fire code: never leave it exposed
Kraft paper and standard foil facings are combustible and must not be left exposed in an attic or any occupied space. IRC section R302.10 requires that insulation facings with a flame-spread index above 25 be covered or separated from the interior, which most asphalt-coated kraft facings exceed. That is why manufacturers print “flammable, do not leave exposed” on the paper.
In practice this means kraft-faced batts on an attic floor should have the facing tucked against the drywall below, not sitting face-up on top where it is exposed. If you are insulating the underside of the roof or a knee wall where the facing would be visible, use unfaced insulation with a separate approved vapor retarder, or a foil-scrim-kraft (FSK) facing rated for exposure, or cover the assembly. When in doubt, unfaced material sidesteps the fire-code issue entirely.
Vapor barrier vs vapor retarder in an attic
Attic facings are technically vapor retarders, not true vapor barriers, and the IRC sorts them into three classes by permeance. Choosing the right class matters more than the “barrier” label, because too tight a retarder in the wrong climate can trap as much moisture as it blocks.
| Class | Permeance (perms) | Common attic material | Typical use |
|---|---|---|---|
| Class I | 0.1 or less | Foil facing, polyethylene sheet | Coldest zones (7, 8); can be too tight elsewhere |
| Class II | 0.1 to 1.0 | Kraft paper facing | Cold and very cold zones (5, 6, marine 4) |
| Class III | 1.0 to 10 | Latex paint on ceiling drywall | Mixed and vented assemblies; often all that is needed |
Per IRC R702.7, a Class I or II vapor retarder is required on the interior side of ceilings in climate zones 5, 6, 7, 8, and marine 4, unless the assembly qualifies for an exception. In a well-vented attic, painted ceiling drywall already acts as a Class III retarder, which is why so many attics need no facing at all. For the full material-by-material breakdown, see the insulation R-value chart.
Faced vs unfaced insulation compared
Faced and unfaced insulation use the same fiber and deliver the same R-value per inch; the only functional difference is the vapor retarder attached to faced product. Choose based on whether the assembly already has moisture control, not on which one feels more premium.
| Factor | Faced insulation | Unfaced insulation |
|---|---|---|
| Vapor control | Built-in retarder (Class I or II) | None; relies on ventilation or a separate retarder |
| R-value per inch | Same as unfaced (about R-3.1 to R-3.4 for fiberglass batt) | Same as faced |
| Best attic use | First layer, cold climate, facing down | Top-up layers, vented attics, hot climates, loose fill |
| Fire exposure | Must be covered; facing is combustible | Fiberglass and mineral wool are non-combustible |
| Cost | Slightly higher for the facing | Slightly lower |
FAQ
Should attic insulation be faced or unfaced?
In most attics, unfaced insulation is the safer default. Use faced insulation only for the first layer on a bare ceiling in a cold climate (IECC zones 5 to 8 and marine 4), with the facing pointed down toward the heated living space. For any layer added over existing insulation, always use unfaced to avoid stacking two vapor retarders and trapping moisture.
Can I put faced insulation over faced insulation in the attic?
No. Laying faced insulation over existing faced insulation creates a double vapor barrier that traps moisture between the two facings, leading to condensation, mold, and wet fiber. When adding a second layer, always use unfaced insulation. If the top layer you already own is faced, remove or slit the facing, or better, buy unfaced material for the top-up.
Which way should the facing go on attic insulation?
The facing points toward the warm-in-winter side, which in a heated home is down toward the living space, in contact with the ceiling drywall. Vapor travels from warm to cold, so the retarder must sit on the warm face to stop indoor humidity from reaching the cold attic. Installing it face-up toward the roof puts the retarder on the wrong side.
Do I need a vapor barrier for attic insulation?
Often no. A vented attic uses its airflow as the primary moisture control, and IRC R806 does not require a ceiling vapor retarder when the vent space above the insulation averages 12 inches or more. In cold climates (zones 5 to 8, marine 4), IRC R702.7 does require a Class I or II retarder on the interior side unless an exception applies. Painted ceiling drywall already provides a Class III retarder in many homes.
Is kraft-faced insulation a fire hazard in the attic?
Kraft paper is combustible and must not be left exposed. IRC R302.10 requires facings with a flame-spread index above 25, which most kraft exceeds, to be covered or separated from the interior. On an attic floor this means the facing goes down against the drywall, never face-up. Where a facing would stay exposed, use unfaced insulation with a separate rated retarder, or a facing approved for exposure.
Can I use faced insulation instead of unfaced if that is all I can find?
You can, but only if the assembly has no existing vapor retarder and your climate calls for one. Install it with the facing toward the warm side and never over an existing faced layer. If you are topping up an attic or you are in a hot climate, do not substitute faced for unfaced; slit the facing or return it and get unfaced material instead.
Reviewed by The Roofing Brief Team. Last reviewed July 2026.