R-Value Basics: Can Insulation Be Used in Lieu of Fire Sprinklers?

Can insulation be used in lieu of sprinklers? If so, does it make sense to do it?

In short, yes. Outside of alarms and smoke detectors, fire protection systems in buildings fall into two categories, active and passive. The fire protection systems you may be familiar with are active, think ceiling water sprinklers or fire extinguishers. But, one could effectively argue that the fire protection systems we all know may not be the best choice all the time.

Passive fire protection systems can reduce building costs and offer additional benefits to building owners and its inhabitants in the unfortunate event of a fire.

Mineral wool & fiberglass insulation (with high R-values) qualify as effective forms of passive fire protection systems. They are low-maintenance choices that offer additional thermal barrier protection in lieu of sprinklers to maintain a building’s integrity and residents’ safety in the event of a fire.

Active vs. Passive Fire Protection Systems:

  • Active: Fire sprinklers are active protection systems as they actively spray water to stop a fire from spreading.
  • Passive: Filling an approved space with non-combustible insulation is a passive system. Fiberglass and mineral wool both have high R-values and are rated as non-combustible with low thermal conductivity. In English, this means it takes a lot of heat to break this barrier, which gives the fire department extra time to get to and put out the fire before too much damage is done.

Both can do the trick when halting the spread of a fire, but which is preferred? We’ve outlined some important factors to consider:


  • Active: Active systems are costly. Not just the price of installing them, but the ongoing need for them to be inspected and maintained have to be considered as well. Also, when a sprinkler system activates, they will flood the area. This means repairs will be needed on all fire-damaged spots, as well as any areas damaged by water from the suppression system.
  • Passive: Filling specific areas with non-combustible insulation (where allowed) saves money. When these areas are filled with noncombustible insulation, they are designed to contain the fire to a small area without the use of damaging liquids or chemicals.

Using Thermal Barrier Insulation to Get More Jobs

Often you will find job opportunities simply because you were able to help someone uncover a more profitable solution they were unaware of. Passive fire protection (from mineral wool and fiberglass insulations high R-values) can be your ticket to bid and get more jobs.

Show architects and building owners the many benefits that come with installing passive systems — and have the right information to back up your claims! But where will you find this information? The National Fire Protection Association 13 standard can be your guide when it comes to noncombustible insulation alternatives.

Fiberglass and mineral wool insulation can be used in lieu of active systems if you follow the NFPA 13 Standards and Regulations

The NFPA 13 Standard for the Insulation of Sprinkler Systems addresses permissible sprinkler omissions for commercial and residential building codes and insulation requirements.

These omissions include an allowance for spaces that can be insulated (and protected) by fiberglass or mineral fiber insulation. The standard is most often applied to areas considered to be concealed spaces. However, even attics in many commercial buildings can be filled with noncombustible insulation and used as a passive fire protection system.

As with anything, local codes may limit the number of stories or size of an area that can be approved, so be sure to check with the Authority Having Jurisdiction (AHJ) in your area!

What you need to know: Breaking down to the basics

All of the information below can be found in the NFPA 13 Standard (if you register for the NFPA you can receive a free full copy.) However, pulled a few key pieces of critical information from the document — and even translated them for you:

Section reads: “Concealed spaces within composite wood joist construction having noncombustible insulation filling the space from the ceiling up to the bottom of the joist of the roof or floor deck…”
Translation: This means that for a mid-floor ceiling assembly, the noncombustible insulation must fill all the way to the deck of the floor above.

Section continued: “and with the joist channels not exceeding 160 cubic feet to the full depth of the composite wood joists.”
Translation: The key word here is “composite.” Previous sections of the permissible sprinkler omissions regulations (which may still be used in your area) required all wood joist areas to be fire stopped or separated every 160 cubic feet, but the language changed in the 2019 standard. This means that every 160 cubic feet composite joist areas will still need to be separated or compartmentalized. Regardless of joist type, work with your local AHJ to comply with their standards. In an attic, the insulation must fill the space from the ceiling upward and be in contact with the rafters.

A recent guide with changes in the national fire sprinkler code outlined some interesting new regulations that made a lot of sense. Take a look at the picture below (found on page 5 of the guide.)

Graphic showing the stories fire teams can reach in a house

When you look at the picture you can see that a fire more than 55 feet above the road surface exceeds the limits of local firefighting resources. This means you’ll have no other choice than to use mineral wool or fiberglass insulation (passive protection) to save a building.

In the article, the National Fire Sprinkler Association lays out the various compliance methods including, “Fill the attic with noncombustible insulation. As in NFPA 13, there is no limit to the volume or area of attic space filled with noncombustible insulation.” Learn more about proper attic insulation here to nail down all the basics for your next job!

Safe Building Construction Must Include Thermal Insulation Barriers

Ultimately, you can use mineral wool and fiberglass insulation as a passive fire protection system in any residential or commercial building. And you should use it to provide the most superior protection and save the building owner financially today — and in the long run!

If you have questions on this blog or any of the mineral fiber wool or fiberglass insulation products we carry, please reach out to your local branch, email us, or give us a call. At IDI Distributors, we work as your partner in insulation — we are here to help, and our goal is to earn your business every day.


Have a question on anything insulation, pricing, or want to place an order? With hundreds of products and countless services, our experts will help walk you through the process of getting ready for your next project. Get in contact with our team today for help and guidance on the right products and best techniques for you and your business.