How to cover fiberglass insulation?

Author: scraper  |  Last update: Friday, July 24, 2026

Covering fiberglass insulation protects the material from damage and keeps airborne fibers out of your living space. The most reliable method is installing drywall over the wall framing. For unfinished areas, you can use rigid foam boards, mesh netting, or fabric panels.

What can I cover fiberglass insulation with?

PIB (Polyisobutylene) can also be used over fiberglass insulation. PIB is a type of vapor barrier that is designed to prevent moisture from penetrating through walls, ceilings, and floors. It is commonly used in basement and crawlspace applications to help prevent moisture damage to insulation and building materials.

Should fiberglass insulation be covered?

Yes, fiberglass insulation should ideally be covered. While it is not always mandatory in unfinished areas like attics, covering it in inhabited areas is crucial for health and efficiency, as it prevents itchy particles from becoming airborne, protects your lungs from irritation, and helps maintain a cleaner, more efficient home environment.

Can you put spray foam insulation over fiberglass insulation?

Spraying foam directly over existing fiberglass insulation is generally not recommended. Spray foam must adhere to a clean surface to create an effective air seal. Spraying it over fiberglass can trap moisture between the drywall and the foam, leading to saturation, mold, and reduced insulation performance.

Should you put plastic over fiberglass insulation?

Double Vapor Barrier – Don't Do It!

The most common and risky error in insulation work is the installation of a double vapor barrier. It occurs when a second vapor material is installed over existing insulation that has its own vapor barrier, such as a polyethylene plastic sheet over fiberglass insulation.

How to Install Fiberglass Insulation | This Old House

What type of plastic to cover insulation?

To cover insulation, use 6-mil polyethylene plastic sheeting, commonly sold at hardware stores like The Home Depot. This acts as a vapor retarder that blocks moisture from entering the insulation and reaching your wall framing.

Does it matter if insulation is unfaced?

Unfaced insulation is great for new construction, remodels, walls, floors, ceilings, basements, attics and crawlspaces. It's best used for interior wall applications that do not face the outside and also in rooms that don't need moisture control, like living rooms, dining rooms and studies.

Why are buyers walking away from homes with spray foam insulation?

Because spray foam can trap moisture, hide the condition of the roof, make it difficult for surveyors to inspect, which means risks like timber decay, dry rot, and not forgetting increased fire risk. If you've got it or you're buying a property that does, this is something you need to know upfront.

Can you spray cellulose over fiberglass insulation?

Yes, you can spray (blow) cellulose insulation over existing fiberglass insulation in an attic, provided the fiberglass is dry. This is an effective "upgrade" method that boosts the R-value, increases fire resistance, and provides better air sealing than fiberglass alone, as the dense cellulose helps block convective heat loss.

What can I put on my walls to keep the cold out?

Effective wall coverings for cold walls include thermal insulation wallpaper (PE foam or cork), insulated lining paper, rigid foam boards, and thick acoustic panels to reduce heat loss and improve warmth. Popular solutions include Adhesive Thermal Insulation Wallpaper (3.28 x 32.8 ft) and 19. 7 in. X 16. 4 ft. Thermal Insulation Wallpaper, which offer easy installation for immediate improvement.

Should fiberglass insulation be faced or unfaced?

Faced and unfaced fiberglass insulation have identical thermal (R-value) capabilities, but they handle moisture and installation differently. Faced insulation includes a kraft paper or foil vapor barrier to prevent moisture damage. Unfaced insulation is bare, making it ideal for layering over existing insulation or friction-fitting between spaces.

Do mice like blown-in insulation?

Mice are curious and always searching for safe, snug, and warm nesting sites. Attics filled with blown-in insulation provide an excellent option–from the mice's point of view. As long as there is a ready food source. Mice are omnivorous and will eat and chew on almost anything including wood and electrical wires.

Can you put stuff on top of insulation?

Storing stuff on top of that will just compress your insulation. For storing things this makes more sense. Compressing your insulation is a terrible idea.

Can you put foil insulation over fiberglass insulation?

To achieve an ultra-efficient insulating system, you can use both fiberglass and bubble insulation foil. By combining these two products, you will effectively stop all modes of heat transfer and maintain the climate control of your home.

How to cover up fiberglass?

To cover fiberglass effectively, it depends on whether you are encapsulating fiberglass insulation (to prevent airborne fibers) or finishing a fiberglass part (like a boat or car panel) for a smooth, painted finish.

Can I just lay new insulation over old insulation?

Installing new insulation over old is a viable option for keeping your home warm in the winter and cool in the summer. However, the current insulation must be in good condition. It's vital that a professional insulation technician inspect your current insulation before adding another layer.

How to cover up exposed fiberglass insulation?

To safely cover exposed fiberglass insulation, choose a method that matches your space's purpose. For ceilings (like in a basement) or walls, use materials that meet local fire codes and keep fibers contained without trapping moisture, which can lead to mold.

Can I spray foam over fiberglass insulation?

Spraying foam directly over existing fiberglass insulation is generally not recommended. Spray foam must adhere to a clean surface to create an effective air seal. Spraying it over fiberglass can trap moisture between the drywall and the foam, leading to saturation, mold, and reduced insulation performance.

What is the healthiest insulation for a house?

The healthiest, non-toxic insulation for your home is natural sheep's wool or hemp insulation. These materials contain no chemical binders or formaldehyde, actively regulate indoor humidity to prevent mold, and do not off-gas.

Why don't insurance companies like spray foam?

The chemical aspect of spray foam makes it very hard for standard insurance companies to provide coverage. Most standard lines insurance carriers want to write the risks with no liability not spray foam contractors that manufacture plastic every day in the field.

Do rodents like foam board insulation?

Foam insulation is a common target because it's easy for them to chew through. The material offers little resistance, allowing mice to create tunnels or nests within the insulation. But mice aren't just interested in chewing for the sake of it—they're also drawn to the warmth and shelter insulation provides.

How much does it cost to spray foam insulate a 2000 sq ft house?

The cost to insulate a new build with spray foam typically ranges from $14,100 to $30,500 for an average 2,000 to 2,500 sq. ft.

Can you leave unfaced insulation exposed?

Unfaced insulation is a plain batt or roll of fiberglass insulation with no facing. It is Class A fire-rated, which means it can be left exposed, or used in specific fire-rated assemblies. Unfaced insulation can also be used with vapor retarders such as polyethylene or polypropylene (depending on local code).

What time of year is insulation cheapest?

What time of year is Insulation cheapest?

  • Winter (December – February): High Demand, Higher Costs.
  • Spring (March – May): Moderate Demand, Competitive Pricing.
  • Summer (June – August): Peak Demand, Higher Costs.
  • Fall (September – November): Best Time to Buy and Install.

What to put over unfaced insulation?

However, most fiberglass and batt insulation require a separate insulation cover or vapor barrier. Insulation materials are typically thick and fibrous. Common types include fiberglass, mineral wool, and foam. Vapor barriers, by contrast, are thin plastic sheets—usually polyethylene starting at 6 mil thickness.

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