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Model #UB-40-P3D-15--47--121

R-15 Thermafiber UltraBatt Unfaced Mineral Wool Insulation Batt 15in. x 47in. (24-Bags)

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  • R-15 Mineral wool batt can be installed within exterior 2x4 wall
  • Easy to cut and install, even around construction irregularities
  • Fire resistant, mold resistant and non-corrosive
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How to Get It

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Product Overview

Thermafiber fire resistance icon

Fire Resistance

Non-combustible insulation resists fire and temperatures in excess of 2000F, giving you more time to get out in the event of a fire.

Thermafiber sound performance icon

Sound Insulation

Outstanding acoustic insulation designed to reduce noise and absorb sound traveling from room to room.

Thermafiber mold icon

Mold Resistant

Mineral Wool is made of an inorganic material that will not promote the growth of mold or retain moisture.

Supplies needed for Thermafiber project

Easy to Install

Thermafiber insulation is easy to install with minimal PPE required.

diagram of Thermafiber install

Measure and Cut

Thermafiber insulation is easy to cut with a serrated knife for custom fitting around electrical boxes, pipes, ductwork, wiring or between nonstandard studs and joists.

diagram of Thermafiber Install

Squeeze and Insert

Thermafiber insulation is flexible and pliable; simply squeeze the sides to compress the insulation and insert into the desired wall.

diagram of Thermafiber install

Release and Expand

Once in place, Thermafiber insulation naturally expands to fill in the space, creating a snug, custom fit.

Thermafiber recycled content icon

Recycled Content

Thermafiber Mineral Wool Insulation is composed of at least 70% recycled content which means you can help protect your home while protecting the environment.

Thermafiber product with logo

Benefits of Mineral Wool

Thermafiber Mineral Wool Insulation products are non-combustible, mold-resistant, non-corrosive and non-deteriorating. (ASTM C 1338)

Thermafiber Fire and Sound package

Thermafiber Fire and Sound Guard

Thermafiber Fire and Sound Guard insulation is designed to provide exceptional acoustical control and fire resistance.

House diagram for Thermafiber Fire and Sound

Where to Install

Thermafiber Fire and Sound Guard insulation is for use in interior walls, floors and ceilings.

Thermafiber UltraBatt Package

Thermafiber UltraBatt

Thermafiber UltraBatt insulation is a dense, semi-rigid batt designed to provide excellent thermal insulation, fire resistance and noise control.

House diagram for Thermafiber UltraBatt

Where to Install

Thermafiber UltraBatt insulation is for use in exterior walls, ceilings, cathedral ceilings, basement walls and crawlspaces.

Thermafiber Ultra-Batt R-30 mineral wool insulation designed to provide excellent thermal insulation in residential and light commercial building. The semi-rigid batts are more dense than traditional batts or rolls and are quick and easy to install. Ultra-Batt products are non-combustible, moisture-resistant, non-corrosive and mold resistant.
  • Dimensions:3.92 ft. x 3.5 in. x 15 in., 6 pieces (29.4 sq. ft. / bag)
  • 24 bags/pallet = 144 pieces/705.6 sq. ft.
  • Mold resistant
  • Provides fire resistance
  • Unfaced Insulation: does not have a vapor retarder
  • Flexible Insulation is easy to cut and install, allowing it to conform to building shapes and construction irregularities
  • Thermafiber Insulation reduces the transfer of heat and cold through building structures to provide thermal comfort and continuous energy savings
  • Step 1 of installation: Measure and cut Insulation
  • Step 2 of installation: Squeeze and insert Insulation into desired space
  • Step 3 of installation: Release and let product expand within the wall
  • Shop all Owens Corning Thermafiber Mineral Wool Insulation here
  • Shop all Owens Corning Thermafiber Mineral Wool Insulation here
  • California residents



Cover Area Per Bag (sq. ft.)29.4 ft²Coverage Area (sq. ft.)29.4 ft²
Product Length (ft.)3.92 ftProduct Thickness (in.)3.5 in
Product Width (in.)15 in


Bag Size3.91 ft. x 24.5 in. x 15 in.Batt/Roll Size3.92 ft. x 3.5 in. x 15 in.
Compatible Install SurfacePlywood,WoodFaced or UnfacedUnfaced
Insulation FeaturesFire Block Rated,Friction Fit,Soundproofing InsulationInsulation Location2x4 Wall,Ceiling Insulation,Floor
Insulation R-ValueR15Insulation TypeBatt
Number of Pieces144Pack Size4
Product Weight (lb.)24 lbReturnable90-Day
Roll or BattBatt

Warranty / Certifications

Warranty Information3-Year Limited

Questions & Answers

Typical questions asked about products:

  • Is the product durable?
  • Is the product easy to use?
  • What are the dimensions of the product?

Customer Reviews

  • 4.3
    out of 11 reviews
  • 75%recommend this product
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Showing 1-10 of 11 reviews
This isn’t just insulation, it’s also an amazing sound-deadening addition...
This isn’t just insulation, it’s also an amazing sound-deadening addition to any walls where you want to keep sound in or out. I’m using it in my basement renovation to keep the the furnace and laundry sounds out of the new rooms.
  • Verified Purchase
Rating provided by a verified purchaser...
Rating provided by a verified purchaser
  • Verified Purchase
  • Verified Purchase
  • Verified Purchase
Great quality and price
Great insulation and price
  • Verified Purchase
  • Recommended
Remodeling the basement and hoping it will help cut heating...
Remodeling the basement and hoping it will help cut heating cost.
  • Verified Purchase
Not wide enough
Tedious width size since house openings are 24" width. A lot of cutting.
Response from OwensCorningDec 17, 2021
Dear Customer.

We are sorry to hear about your experience. Please feel free to contact us at 1-800-GET- Pink to discuss your situation further.

Thank you!
Owens Corning
  • Verified Purchase
Calculator on website is wrong
The calculator supposedly will give you the amount you will spend for insulation needed once you put in the the square footage. However, it multiplies the square footage times the price of one pallet (24 bags). One bag covers about 29 sq. ft. and one pallet (24 bags) will cover about 705 square feet. That means I will pay $925 (as of 8/9). If you use the calculator and enter 5 sq. ft. x 6 sq. ft. which equals 30 sq. ft. the price will be over $27,000! Please don't trust the calculator. Do your own math until the website administrators fix it.
Response from OwensCorningAug 10, 2021
Dear kdl4082,

Thank you for bringing this to our attention. We will ensure the proper person is notified.

Thank you!
Owens Corning
    • Recommended
    Very good quality very happy with it even the building...
    Very good quality very happy with it even the building inspector said it was above and beyond what they were expecting install extremely easy
    • Verified Purchase
    Excellent product. I bought the saw that was linked with...
    Excellent product. I bought the saw that was linked with the insulation and it does an excellent job of shaping and cutting the batt. Very easy to squeeze and place between the wall studs and behing the wires crossing thru the studs. Light to handle and move around
    • Verified Purchase
    Showing 1-10 of 11 reviews