#1 Home Improvement Retailer

Internet #205972541

Model #RXCB351525

R-15 ComfortBatt Fire Resistant Stone Wool Insulation Batt 15 in. x 47 in. (12-Bags)

  • Maintains R-Value year after year
  • Fire Resistant & Water Repellent
  • Ease of Installation - Cuts Easily & Friction Fits
  • See More Details

Frequently Bought Together


Product Overview

ROCKWOOL COMFORTBATT is a semi-rigid stone wool batt insulation for exterior wood and steel stud applications in both new construction and renovations. It features a unique flexible edge designed to compress as the batt is inserted then spring back, expanding the batt against the frame studs to give a complete fill. This flexibility ensures the expected R-value is achieved and maintained. On-combustible and fire resistant, COMFORTBATT will not develop toxic smoke or promote flame spread, even when exposed directly to a fire. It is also offers water and moisture resistance and excellent sound absorbency. COMFORTBATT is an effective way to improve a home's energy efficiency. It is GREENGUARD Gold Certified and contributes to a healthier indoor environment.
  • Fire resistant due to its high melting temperature of 1177°C (2150°F)
  • Excellent sound absorbency growth
  • Water and moisture resistant; does not absorb moisture to maintain insulating value
  • Easily cut
  • Does not rot or promote growth of fungi or mildew
  • Flexible edge springs back, expanding the batt against the frame studs to provide a complete fill
  • GreenGuard gold certified for indoor air quality
  • 12-bags included on a pallet
  • Click here to learn more about Eco Options and Energy Efficiency
  • Buying guide and insulation calculator:

    insulation buying guide
    Insulation calculator button

Info & Guides

You will need Adobe® Acrobat® Reader to view PDF documents. Download a free copy from the Adobe Web site.

Compare Similar Mineral Wool Insulation

current product
Top RatedR-15 ComfortBatt Fire Resistant Stone Wool Insulation Batt 15 in. x 47 in. (12-Bags)
Thermafiber Fire and Sound Guard Unfaced Mineral Wool Insulation Batt 23 in. x 47 in. (16-Bags)R-23 Thermafiber UltraBatt Unfaced Mineral Wool Insulation Batt 15in. x 47in. (24-Bags)
BrandROCKWOOLOwens CorningOwens Corning
NameR-15 ComfortBatt Fire Resistant Stone Wool Insulation Batt 15 in. x 47 in. (12-Bags)Thermafiber Fire and Sound Guard Unfaced Mineral Wool Insulation Batt 23 in. x 47 in. (16-Bags)R-23 Thermafiber UltraBatt Unfaced Mineral Wool Insulation Batt 15in. x 47in. (24-Bags)
Insulation Location2x4 Wall,Attic,Basement,Ceiling Insulation,Crawlspace,Floor2x4 Wall2x6 Wall,2x6 Wall
Product Thickness (in.)3.5 in3 in5.5 in
Insulation FeaturesFriction FitFire Block RatedFire Block Rated,Fire Block Rated
Insulation R-ValueR15 R23
Number of Bags1211
Compatible Install SurfaceWoodPlywoodPlywood,Plywood
Roll or BattBattBattBatt
Faced or UnfacedUnfacedUnfacedUnfaced
View ProductView ProductView Product



Coverage Area (sq. ft.)
Product Length (ft.)
3.91 ft
Product Thickness (in.)
3.5 in
Product Width (in.)
47 in


Bag Size
48 ft. x 16 in. x 24 in.
Batt/Roll Size
3.91 ft. x 3.5 in. x 47 in.
Compatible Install Surface
Coverage Area per Bag (sq. ft.)
Faced or Unfaced
Insulation Features
Friction Fit
Insulation Location
2x4 Wall,Attic,Basement,Ceiling Insulation,Crawlspace,Floor
Insulation R-Value
Insulation Type
Mineral Wool Insulation
Number of Bags
Pieces Per Bag
Pieces per Pallet
Product Weight (lb.)
Roll or Batt

Warranty / Certifications

Warranty Information

Questions & Answers



Asked by ej February 5, 2021

Comfortbatt is available as 3.5" R15, 5.5" R23, 7.25"R30, 9.5" R38. Dependant on the R value you wish to build and the depth of space available you can use one or more layers to build R Value

If I'm replacing the siding does it matter which way faces out?

Asked by JC October 6, 2020

The side with print on it should face out.

how many bags to insulate a 26x36x10 garage

Asked by bobthebuilder September 26, 2020

For example - For each wall 26' Length x 10' Height - Approx 260sf / 36' Length x 10' Height - Approx 360sf Total of 620sf Each pack of product sized 3.5" for 16"oc covers approx. 60sf. Which would be approx. 11packs

I'm confused. In reading thru the information about the ComfortBatt exterior walls products, I do...

Asked by LES1003 June 5, 2020

The use of vapor barriers is dictated by your local code requirement typically and this can change dependent on the climate zone you are in. Can you email us direct with this question and we can reply direct with additional information. Email to contactus@rockwool.com

I only need 5 bags, not entire pallet

Asked by Nathan May 24, 2020

You can order by the bag if it’s stocked locally at a store and can be purchased at that location. If it is not stocked locally at a store, it can only be purchased in 12 bag increments.

Is this safe to use around standard two plug electrical outlet box?

Asked by Mlee6 May 10, 2020

Yes, we used the rockwool throughout the whole house and no problems. The rockwool is suppose to be fire resistant or proof.

Is this material sound proof as well?

Asked by Lut March 14, 2020

All ROCKWOOL will provide some sound and some thermal value due to the nature of this rock based mineral wool. COMFORTBATT R15 would be expected to perform similarly to 3" SAFEnSOUND

Can you lay this product over suspended ceiling tiles, troffer fixtures, etc?

Asked by Sniggud March 12, 2020

In theory yes, however note we do not test in suspended ceiling systems. One factor to consider is that your ceiling grid is strong enough to hold the weight of the batt insulation. Email us direct at contactus@rockwool.com for further support, if required

Can this be used in the basement ceiling? Do you recommend a vapor barrier? I wasn't planning on finishing with drywall.

Asked by Chris February 5, 2020

Yes you can use this as an option for walls, floors, ceilings, attic space and crawl space. Wood or steel stud framing dimensions available

Can I use this in a tent type carport, going about 4-5 feet up to deaden sound transfer from one ...

Asked by ML February 2, 2020

A tent type carport will not give you any true way to affix it or hold tight to the fabric. You will also need to have a vapor barrier for this type of insulation. This insulation will also hold water so exposed to elements would not be in your best interest. You may want to explore a foam insulation. It can be spray glued in place and wont wick or hold water. Hope this bit of info helps in your endeavor

R-15 ComfortBatt Fire Resistant Stone Wool Insulation Batt 15 in. x 47 in. (12-Bags) - page 2

Customer Reviews

  • 4.9
    out of 506 reviews
  • 99% recommend this product
Filter by:
Showing 1-10 of 506 reviews
Insulation installed easily, no airborne fiberglass to inhale or itchy...
Insulation installed easily, no airborne fiberglass to inhale or itchy rash. Cuts easily with a serrated saw (bread knife)! Made my cabin much quieter and keeps the heat in. I expect it to keep it cool in the warmer months as well.
by Harry
The best product!
I have replaced all of the old 1955 insulation in my home and i am working on the last room right now.I'm using R14 for 2 x 4 application inside my walls.I am so glad that i'm using Roxul as it has already shown to lower my heating bills and the accoustics changed right away.I don't hear much noise outside anymore.It is so easy to install and it's not itchy,i'm cutting the pieces with a bread knife.Thanks guys for a great product!
by Andreas
It's easy to work with, not as dusty as fiberglass. I love its water repellent and fire resistant...
It's easy to work with, not as dusty as fiberglass. I love its water repellent and fire resistant qualities. Even though it is quite a bit more expensive than fiberglass, it's long term durability makes it worth the price. It is stiffer and more dense than fiberglass which makes it easier to cut and shape as needed. I just used a bread knife.
by Greenfarmer
1 person found this helpful
This should make regular fiberglass insulation obsolete
I'm remodeling my 1950 mid century modern home one room at a time. I started with the hardest room to heat & cool, knocked out the old plaster & had the room sprayed with rigid & soft foam. The guys rushed the job & left some thin spots and even bare wood showing thru. I wanted to fill voids with Roxul but could not find it anywhere in Oklahoma so I hung the drywall anyway. Since then I've found a dealer 30 miles from me that can order it. I've since used Roxul in my sun room & garage. I like it better than the foam & I can easily install it myself.
by Dogwalker
Fast install, easy to work.
Fast install, easy to work.
by Ridgecrest
2 people found this helpful
Better Conformance to Joist Spacing
Fiberglass batts depend on springback to original shape, from large compression in packaging. That springiness then results in buckling if a bit oversize for the space. Rockwool doesn't do this. Lost contact with confining surfaces destroys insulation value.
by Attic Access
130 year old church restoration, ideal product
Installing comfort batt insulation in the walls and floor of a 130 year old William Critchlow Harris church/cottage upgrade. As this structure is a 'balloon' design, fire concern was paramount. Simple installation even with so many cuts, and huge long term benefits. Ideal application for your product.
by Michael
I am happy with this product.
I like it when i get asked what i'm putting into my walls.I let friends know that this product is safe to handle and not itchy.I'm using a bread knife to cut pieces to fit.I've got peace of mind knowing it's not going to grow mold,it's fire resistant,easy to install and i won't hear as much outside noise in my home.Right now i am installing this product and i am 3/4 completed.
by Andreas
We won't use anything but this product in our builds!
We do both custom and high volume manufacturing for tiny homes on wheels. It's important to us that the products we spec out to use are easy to install and work effectively for our applications. This product does exactly that. Sounds carry far and wide even in tiny homes. So, when we have new families moving into a small space, this product makes an excellent noise dampener in between closed off rooms to provide an element of privacy where it can normally be hard to find. Nevermind its obvious positives, this product is just far superior at the end of the day. It's our gold standard for each home that we send out of our shop and it makes us proud!
by Tina the Contractor
Ive been a fan of Roxul aka "Rockwool" ever since Mike Holmes Introduced it to his show Holmes on Homes. Had to wait a couple of years before it came to the States but when it did, i was elated!!! I got to try the water test and burning it, and boy was it amazing, just as described and show. I will never ever use the pink insulation ever again!! Re-insulating that garage picture i sent you in 90degree heat, after done that garage kept a temp of 70 degrees, i was extremely impressed!! ROXUL HEAD 4 LIFE!!!!!!!
by Coach
Showing 1-10 of 506 reviews