Can You Compress Mineral Wool Insulation?

Mineral wool insulation is significantly different from fiberglass batt insulation. Not only is it made of a different insulative material, but its R-value, compression rates, and cost will vary as well. But can you compress mineral wool insulation? And if so, by how much? We have done a bit of research on mineral wool insulation. In this post, we will answer these questions.

No. You can't compress mineral wool insulation because it is already compressed during the packaging process. Since it's compressed beforehand to offer a higher R-value, it retains its R-value fairly well under various conditions. This is another reason why it is more expensive than fiberglass and cellulose.

Mineral wool insulation can go in several places in your home. You can use it in the attic, walls, basement foundation, and flooring. However, the great thing about this type of insulation is that you don't have to worry about it becoming damaged from water, losing its R-value, or growing mold. Continue reading to learn more about it and its benefits.

Worker man in overalls working with rockwool insulation material. Can You Compress Mineral Wool Insulation

More On Mineral Wool Insulation

You may also hear this insulation referred to by a familiar brand name, Rockwool (Roxul). This type of insulation has about a 25-35% higher R-value than other insulation types, including recycled material, fiberglass, and cellulose.

Its density is two to three times greater than fiberglass, and you can expect to pay anywhere from 25-50% more for it than what you pay for fiberglass.

Also, mineral wool insulation can be cut to fit inside walls or any other interior areas. However, unlike fiberglass batts, you'll typically need to cut it with a large serrated knife or saw due to its high density. The great thing is that even after the insulation is cut, it will still hold the same density and volume per square inch.

Cutting Mineral wool with utility knife

How much does mineral wool insulation compress?

Before mineral wool insulation is shipped, it is compressed and then tightly sealed in plastic wrapping. This means that once it arrives on your doorstep [or at the home improvement store], you won't be able to compress it any further.

So it's best to ensure that you measure your home areas accurately so that the insulation is cut precisely to fit. The last thing you want is to order too much of this pricey installation only to find that you needed about half of that.

Does insulation lose R-value when compressed?

Yes, this is typically the case when you compress fiberglass or recycled material installation. You can increase its R-value this way.

However, the amount by which you can replace the R-value will vary, but on average, you can increase it by about 20% to 30%. This isn't possible with mineral wool insulation, given that it's already compressed to the maximum of its ability.

Can you put too much insulation in walls?

Over insulating a wall isn't typically thought of when it comes to residential homes and small businesses. Usually, people are worried about under-insulating a space. This isn't a common problem with wall insulation, though it's more common with attics [as it can cause ventilation issues].

However, if you place too much batt insulation in the walls before drywall is installed, it can cause you to have to re-measure the drywall to fit for a smaller, tighter area. It can also create issues from increased moisture levels. However, suppose you plan to install blown-in insulation in walls that are already erected.

In that case, the insulation may start to pour out of any open areas on the wall, such as wall sockets or pipe openings. This can make a bit of a mess and waste insulation. And of course, it can also cause issues with room-to-room temperature regulation and humidity levels.

Advantages of mineral wool insulation?

Mineral wool insulation has its advantages over many batt alternatives. If you have a new home project and plan to improve its efficiency, here are a few things to consider when considering this type of insulation.

Work composed of mineral wool insulation in the floor, floor heating insulation , warm house, eco-friendly insulation, a builder at work

It's easy to install

It's pretty easy to install because mineral wool insulation is thick and doesn't flop around as fiberglass does. You only need to cut the insulation and slide it into the wall cavity or between floor joists.

You don't have to worry about applying adhesive or stapling the insulation. It will simply stay in place on its own. Also, since the insulation is already compressed, there's no need to worry about increasing its R-value by squeezing it with additional layers.

It's easy to use in irregularly shaped areas

Mineral wool insulation is very dense and has an almost cake-like viscosity. This makes it easy to cut and carve holes such as wall outlets, PVC pipes, vents, and other wall and ceiling obstructions that you will run into during the installation.

It's best to use a long tool such as a reciprocating saw to hacksaw to cut this insulation, especially if you're using batts that are over four inches thick.

It's easy to measure

If you've ever worked with fiberglass insulation, you know that it can be challenging at times when it comes to cutting and measurements. It's also very itchy and is known to crumble up when you attempt to cut or measure it.

The rigidity of mineral wool insulation makes it easy to size with the tape measure for accurate measurement.

It's readily available

Though you may pay more money for mineral wool insulation per square inch, the good news is that it is readily available at your typical hardware store. Different brands keep this insulation in stock, including Roxul, Thermafiber, and Johns Manville.

Termal insulation installing at the attic

It's fire-resistant

Mineral wool insulation is naturally fire retardant thanks to the keratin protein contained and natural wool fibers. And it's typically coated with chemicals to make it fire-retardant.

If this insulation should happen to catch fire, the mineral wool will retain its shape and hold up well against spreading flames. If the insulation comes into contact with the flames, it will simply burn and then crumble into dissipating ash. In other words, it won't exacerbate the fire.

It holds up well in water

Another great benefit of this insulation is that it doesn't absorb water. This means that it will stay intact even when it becomes wet. This is why it's such a popular choice in attics and basements.

If there is a water leak, busted pipe, or broken water heater in your home, you can expect that this insulation will hold up way better than cellulose and fiberglass. However, efforts should be made to dry it out as soon as possible because it can still grow mildew if left in a damp state.

Sound deadening properties

Not only is mineral wool insulation great for helping your home regulate temperatures, but it also can work as the perfect soundproofing material. The density and size of the batts make it very difficult for sound to pass through.

So if you have a home studio or are worried about sounds from the neighbors or the outside entering your home, mineral wool insulation may be a good solution.

Higher R-value

The thickness of mineral wool insulation will be a bit better when it comes to insulating properties per square inch. Compared to fiberglass batt, mineral wool batts of the same size will have an R-value of about 15 to 20 percent higher.

How long does mineral wool insulation last?

On average, you can expect mineral wool insulation to last anywhere from 30 to 40 years or more. This type of insulation is designed to last the entire lifetime of your home.

The reason it's able to last so long is that it doesn't decay, as it's inorganic. Therefore, it'll retain its properties for quite some time. It also lasts longer because it's less susceptible to physical damage caused by fire, flooding, or pests.

Work composed of mineral wool insulation in the floor, floor heating insulation. Can You Compress Mineral Wool Insulation

Wrapping Things Up

If you're looking to install or replace insulation in your home, mineral wool batts can do the job. Though you will pay more per square inch for this insulation, it will work impeccably to help your home regulate temperatures. It's less likely to become damaged from water or fire.

Before you go, be sure to check out our other posts:

What R-Value Is 6 Inches Of Insulation?

Best Insulation For Ceiling Under Roof?

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