There seems to be many people who either believe that mineral wool and fibreglass are the same insulation or that they’re similar enough that the differences don’t matter. We’ll admit that we take insulation a tad more seriously than most people, but we think understanding the difference between these two products can help contractors and even homeowners make the best decision when building or renovating.
Fibreglass is made from extremely fine and long fibers of glass that are woven together and lightly compressed. The length of the fibers helps the glass to keep its form, which means it’s easy to find fibreglass in batts, rolls, and loose film.
Mineral wool is made of volcanic rock instead of glass. It’s quite similar except the fine fibers are much shorter, so the mineral wool must be more compressed in order for the insulation to keep its form. This extra density means that mineral wool is actually a better insulator than fibreglass and provides better sound proofing. However, it also means that mineral wool comes almost exclusively in batts. Other forms do exist, but they’re hard to find.
R Value.
Fibreglass has a fairly wide range of R values depending on whether it’s a high quality product and where you’re buying it. In Canada, Fibreglass and mineral wool have fairly similar R values, and you likely won’t see much difference. However, if having the very best R Value is your top priority, mineral wool is usually slightly higher.
Durability.
Mineral wool significantly beats out fibreglass in terms of durability. Water damage, which basically destroys fibreglass, doesn’t particularly affect mineral wool. In fact, mineral wool simply doesn’t absorb water at all, so it’s highly resistant to corrosion, fungi (mould, mushrooms, mildew), and bacterial growth. Fibreglass, on the other hand, easily becomes soggy and stops working. Fire protection is another point for mineral wool. While fibreglass isn’t exactly flammable, mineral wool is literally made from volcanic rock. It’s so fire resistant that it’s a preferred insulation for firestopping.
Environment.
Mineral wool is usually around 70% recycled material compared to fibreglasses 20-30% recycled material. Between that difference and mineral wool’s improved durability and R value, environmentalists often recommend mineral wool over fibreglass.
Cost.
Fibreglass is the winner for cost. You’ll likely see about a 10% difference per batt, but it’s worth noting that the R-value is likely slightly smaller as well. You may see the extra 10% investment for mineral wool is well worth the higher upfront cost.
At Westcal Insulation, we like to help Albertans make informed decisions about which insulation products best suit their project and priorities. But it’s worth noting that you don’t have to choose one or the other, you could use mineral wool where you need it most — in firewalls or the attic, where dampness may be an issue, and use fibreglass elsewhere to save a little money. To learn more about insulation or to invite bids for your project, contact Westcal Insulation today.
