Fiberglass isn’t the only game in town when it comes to insulating your home or new construction project. Mineral wool and spray foam are two additional options that have gained the attention of builders, but. Which option is best? When it comes to deciding between mineral wool or spray foam, each has its perks and drawbacks. This article compares the two popular insulation types and also presents a third option to consider for covering your building envelope.
What is Mineral Wool Insulation?
Mineral wool insulation is spun from natural raw materials derived from volcanic rock or slag (a byproduct of molten metal production). It can take the form of boards, batts, or loose-fill blown-in insulation. It’s a popular choice for use inside wall cavities, and it has superior insulating and sound-dampening properties when compared to traditional fiberglass.
What is Spray Foam Insulation?
Spray foam insulation, also called SPF or spray polyurethane foam, is a chemical compound that is sprayed directly onto surfaces on the jobsite and it hardens permanently into insulation. The main chemical component in spray foam insulation is polyurethane. There are two main types of SPF: open and closed cell, depending on the mixture. The differences between the two types of spray foam insulation are shown below:.
Differences Between Open and& Closed Cell SPF
Mineral Wool vs. Spray Foam Insulation
When choosing between mineral wool or spray foam insulation for your project, there are many factors to consider:.
Thermal Performance
R-Value is the measure of thermal resistance, which tells you how well your insulation will perform. Mineral wool and open cell spray foam both carry a similar R-value, between R3 to R4 per inch—while closed cell spray foam has a significantly higher thermal resistance, between R6 and R7 per inch. This means you can achieve thermal performance goals with a thinner layer when choosing a closed cell spray foam.
Applications
Both mineral wool and spray foam can be used to insulate walls, floors, and ceilings. Mineral wool cannot be left exposed and walls must be covered and finished. Spray foam insulation can be used for additional applications, including roofs and unfinished attic floors. Spray foam can also cover irregular and difficult to reach areas without requiring a separate finishing layer.
Installation
Mineral wool is easier to install and doesn’t require as much equipment as spray foam insulation. Modular mineral wool boards and batts are simply fastened into place with nails and oversized washers. Spray foam requires professional equipment, installation expertise, and special safety equipment. Some DIY spray foam insulation kits are available, but there are risks to performing this specialty scope without experience.
Cost
Spray foam insulation is more expensive than mineral wool insulation. Specialized equipment and professional installation, required with SPF, can drive the final cost up even further.
Sound Dampening
Mineral wool is far superior to spray foam insulation when it comes to soundproofing and sound dampening. Below is a comparison of sound blocking performance taken from 3” thick sections of each insulating material.
Sound Dampening Properties: SPF vs. Mineral Wool
Air Barrier
An air barrier prevents the movement of air and drafts through your walls. Spray foam insulation functions as an air barrier because it completely seals up all cracks and crevices. Mineral wool is air-permeable, but it allows air to flow through it. A separate air barrier, such as polyethylene sheeting, is required to restrict air flow through mineral wool insulation.
A Superior Alternative: Polyiso
If you’re still not sure which choice to make when comparing mineral wool to spray foam insulation, there is another alternative to consider—polyiso. Polyiso insulation comes in a variety of modular foam boards, carries a high R value per inch, and offers facer versatility to meet specific design and performance criteria. See how polyiso compares to spray foam and mineral wool insulation below:.
Comparison: Polyiso - SPF - Mineral Wool
Maximizing Your Investment
Picking the right insulation can pay off in the long haul when your insulation performs. Rmax is dedicated to helping you find the right insulation for your project.
Email your local Rmax representative now to make sure you’ve got the materials to maximize your investment!