Insulation..Which way round ie. foil facing inwards or ...

> Thanks, I have started to put the insulation in place
with the foil facing inwards however I feel that the
foil should face outwards as I have also looked on
the Celotex website and their diagrams show the foil
as facing outwards.

Celotex has foil on both sides, what exactly have you bought?


> Another question: My house was built in the 30s and the
rafters are not all standard dimensions apart from
each other and also vary by a couple of inches from
the wall plate to the ridgeboard!!! The insulation is
not sitting snugly as I like and resulting in
slight gaps along the edges. Is this a problem?

Yes, it HAS to be a tight (airtight) fit. This requirement is the reason behind the high costs of professional installation, as it's a labor-intensive task. The best course of action is to fill in the gaps using expanding foam. It’s advisable to tackle all gaps in one go to avoid wasting foam; half-used cans are often ineffective.

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Understanding the correct orientation of insulation facing is crucial when installing insulation anywhere in your home. The "facing" refers to the paper or foil side of insulation products. It should always be installed toward the heated or air-conditioned area of your home. This setup ensures a vapor barrier that prevents moisture from infiltrating and becoming trapped in the insulation.

Types of Products

The two primary categories of insulation that utilize facing are:

Fiberglass insulation is created from melted glass that is spun into fibers and comes with a paper facing on one side, which acts as a moisture barrier.

Mineral wool insulation is made from natural materials such as basalt or slag, and it too features either a paper or foil facing to obstruct moisture.

Both fiberglass and mineral wool batts are available in faced and unfaced variations. Unfaced products are better suited for interior walls, while faced products should be utilized on exterior walls, attics, and crawlspaces.

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Which Way to Install Facing

When dealing with faced insulation, the facing should always direct towards the interior, heated, or air-conditioned living space.

For example:

• On exterior walls, the facing should be in contact with the drywall.
• In attics, the facing should face downward toward the ceiling below.
• Below floors, the facing should point upward toward the subfloor above.

The insulation's facing paper serves to block moisture from condensing within the insulation. Incorrect installation could result in moisture being trapped between the facing, leading to mold growth, deterioration, and a decrease in R-value. The R-value measures the insulation's thermal capability.

Vapor Barriers

The insulation facing acts as a vapor barrier, resisting moisture infiltration, and preventing humid indoor air from condensing on cooler surfaces. In colder climates, vapor barriers should be placed on the warm side of the insulation; in hot, humid areas, they should be positioned on the exterior side.

Even when faced insulation is installed correctly, having an additional vapor barrier toward the heated space is advisable for extra protection against moisture. Suitable options for dedicated vapor barriers include:

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

Is Proper Facing Direction Crucial for Insulation?

Absolutely, the facing direction matters greatly when installing insulation. Improper installation can cause moisture accumulation, mold growth, material decay, and reduced insulation efficiency. Properly installing insulation ensures your home's R-value and overall structural integrity remain intact. Skipping corners in insulation practices can have detrimental effects; accurate installation is essential for optimal results.

FAQs About Facing Insulation

Should I staple the facing?

Yes, in most instances. Securely fastening the facing to studs or joists with staples is important to prevent sagging or shifting. Staples further enhance the integrity of the vapor barrier.

Should I compress the insulation?

No. It's crucial to allow the insulation to reach its full thickness without compression, which would reduce the R-value. Tightly staple the facing while avoiding air gaps or puckering.

Can faced insulation cause condensation?

When installed correctly, directing the facing toward the interior prevents condensation. Incorrectly oriented facing can trap moisture inside the insulation, leading to significant problems.

Should I use both vapor barrier and faced insulation?

Yes, using both together is recommended. The facing acts as a vapor barrier, but adding a separate vapor barrier (like plastic sheeting) on the inside provides enhanced moisture defenses.

What if I install the facing backward?

If you discover this mistake, it is essential to reinstall the insulation correctly. Leaving the facing toward the exterior traps moisture inside the insulation, promoting mold growth, degradation, and decreased performance.

For more Foil Faced Insulation Board information, please contact us. We are ready to provide professional guidance.