Insulation has become one of the components of a modern home that you just can’t live without nowadays.

Even if you’re not concerned about the environmental impact of it, just having the simple ability to keep the temperature inside your home consistent for longer makes insulation so useful. And that’s before we even consider the amount of money you can save from the improved energy efficiency that you get. 

When you shop around for insulation options for your home, you will very likely come across two products in particular—Owens-Corning Thermafiber and Rockwool insulation. 

Now, both of these insulation options are already designed to work well in their target use cases. As such, we will be guiding you through the design factors you need to think about so you can choose what works best for you. 

The General Comparison

To save time and avoid getting too technical, we won’t be diving into the detailed specifications of Thermafiber and Rockwool insulation. We’ve also done this because, for the most part, Thermafiber and Rockwool are actually the same thing. 

Both of these products fall under the classification of mineral wool insulation. As the name suggests, mineral wool insulation is made up of rocks and slag (mineral byproducts from metal production) that are molten down and drawn out to create a fibrous material. 


Rockwool and Thermafiber are each made with a proprietary mixture of minerals and slag to give them their specific characteristics; but as we said earlier, both are similar enough to each other that we can safely ignore most of the tech specs.

Things to Consider

While it is always an option to just pick either of the two insulators at random and be none the wiser, Thermafiber and Rockwool do still have their differences that can make one perform better than the other in certain situations. 

To help you make your decision, we’ve listed down some of the things you will want to consider before you choose which insulator to buy. 

Arguably the most important thing to understand when choosing between Rockwool and Thermafiber is that they are not single products, but rather brand names with many different products intended for specific applications.

For instance, each brand has their own formulation of mineral wool that is designed to block noise more effectively than standard insulation, which is achieved by packing the wool material a bit more densely than normal as this helps with absorbing lower frequencies.

The same also goes for general insulators as well, with certain variants that are intended for use in commercial applications like buildings and manufacturing plants as opposed to residential applications. 

Industrial-grade insulators may be made with flame retardants designed for extremely high temperatures—something your average home will likely never experience.

When it comes down to it, then, your final purchase decision ultimately rests on what specific model of insulation you need for your home, rather than the brand of insulation you want to get.

For the sake of convenience, though,  we will be comparing Thermafiber Ultrabatt and Rockwool Comfortbatt to explain some of the other considerations you need to look into.

Another important consideration when buying any insulation is the r value of that insulation. r value is simply the measure of how well an insulator is able to block the heat that goes through it.

In general, your home will need different r values for insulation depending on which part of the house they are, the reason being that some areas will receive more heat than others and therefore require more protection from it. 

Of course, you probably won’t need to spend too much time worrying about which variant to get as your local building code will usually have those laid out for you. as a rule of thumb though, your roof or attic space will need a higher r value than that of your walls. 

Another important thing to think about is how well the insulation is able to hold up not just during installation but over the long term.

Comparing Thermafiber and Rockwool, both options performed quite well in this regard thanks to the fact that they are both mineral wool insulation. 

As we touched on earlier, mineral wool is made up of molten rocks and minerals which makes it almost completely inorganic. Inorganic materials, for the most part, have very good resistance against fire, insect damage, and decay from mold and mildew.

Once you’ve mostly shortlisted your choices, the next thing you will want to worry about is the ease of actually installing the insulation.

For most people in most situations, we will recommend having a professional contractor handle the installation for you because of the safety precautions and equipment that is needed to do this safely. 

However, if you do plan on installing your insulation by yourself, it is generally a good idea to figure out how the insulator feels in the hand as you carry it around and install it.

In our opinion, Rockwell is something we prefer for more situations as their Comfortbatt insulation is semi-rigid and therefore doesn’t flap about too much when you are installing the insulation into a wall. On the other hand, the flexibility of Thermafiber does make it more suitable for filling in tricky corners and spaces. 

As we said earlier, mineral wool insulation comes in multiple variants, so you would want to look into their catalogs to find exactly what works for you.

Last but certainly not least on this list is the question of cost and value. with all else being equal, you will naturally want to choose the insulator that you can buy for cheaper. Of course that is never actually the case in the real world, and especially not with Rockwool and Thermafiber. 

As an example, we have had some experience with thermafiber insulation being a bit flaky and releasing some amount of dust particles during installation. 

Considering that rockwool tends to be more expensive than thermafiber of an equivalent spec, this will be the kind of value judgment you will need to make when considering one or the other for your home.

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Matt Greenfield

Matt Greenfield is an experienced writer specializing in home improvement topics. He has a passion for educating and empowering homeowners to make informed decisions about their properties. Matt's writing focuses on a range of topics, including windows, flooring, HVAC, and construction materials. With a background in construction and home renovation, Matt is well-versed in the latest trends and techniques in the industry. His articles offer practical advice and expert insights that help readers tackle their home improvement projects with confidence. Whether you're a DIY enthusiast or a seasoned professional, Matt's writing is sure to provide valuable guidance and inspiration.

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