What Material Is Used to Fireproof Safes

Safes have been around for many years because, as humans, we are always concerned about keeping our valuable treasures and documents close to us. With time, protecting these things from burglary and fires has become necessary.

This way, fireproof safes were created. I am sure you are wondering, what material is used to fireproof safes?

Well, we shall see by the end of this article. Yes, they will catch fire but depending on the material used, they can withstand it for some time.

It could be alum, gypsum or other fire-resistant materials.

The basic design of fireproof safes began in the early 19th century. Their plan includes a double-walled body to help it withstand heat for an extended period. The space between the double walls is then filled with fire-resistant material.

Among the many materials that can be used to provide insulation for your fireproof safe, I would recommend “Gypsum.”

However, some of these safes can also be insulated using a blend of poured-in material that works just as well as gypsum, but is not as resistant.

Many low-cost fireproof safes use simple gypsum for insulation, while high-end safes use a more enhanced form of gypsum combined with other ingredients for more robust insulation.

Now that we have seen what material is used for fireproofing safes, let’s see how exactly gypsum works and what options you have regarding fireproof safes. However, before we dive in, let’s look deeper into this safe design.

The Design of a Fireproof Safe

design of fireproof safe

As we have stated, fireproof safes have a double wall. These walls are often made of metal or fire-resistant concrete. Each safe has its own patented formula, and each door has a fire seal for enhanced security which will expand in the event of a fire.

With the insulation material poured in between the two walls and the fire seal, your safe will protect your items for a while, allowing you to put out the fire without losing a thing.

This design protects your valuables from water or other material used to extinguish the fire.

Gypsum: The Best Material to Fireproof your Safe

Also known as drywall, sheetrock or fireboard, the chemical name for gypsum is Hydrous Calcium Sulfate (CaSO4-2H20), a naturally occurring element.

Even with how much it resists heat, it is pretty light and is made up of oxygen, calcium and sulfur. This material is combined with water and other chemicals for better protection. Though it is a naturally occurring element, it can still be made through industrial processes.

Gypsum became very common during World War 2 when the US was building war bombs, and this was because it was and still is cheaper than plaster and traditional lath.

How Gypsum Protects your Treasures

  • Your fireproof safe still heats up in the event of a fire

Even with insulation, your safe can’t avoid the intensity of the heat produced by a fire. However, it is designed to absorb the heat, which is then transferred to the next layer after the outer wall, which could mostly be gypsum.

  • A chemical reaction then takes place, buying you more time

Gypsum goes through a calcination process once the temperatures rise to 80 degrees Celsius. Since gypsum has H2o chemical bonds, this chemical reaction works to dissolve the water chemical bonds within it.

This reaction is how your property is kept safe. It needs a lot of heat to occur, making sure that it absorbs as much heat as possible, delaying any damage to your valuables.

Once the gypsum between the two walls on your fireproof safe absorbs the heat, it is converted into steam and paris. At this point, the gypsum’s fire resistance has expired because it has run out of steam.

However, the steam produced during the chemical reaction is of value. I9t creates pressure inside the walls of the safe, baring smoke from reaching the items within the safe. An excellent inner door seal also assists this process.

Are you looking for a Fireproof Safe? Consider One of These Three!

  • Composite safes

These safes have proudly carried on the 19th-century tradition of fireproof safe design, and they would be my first option when purchasing a safe.

Composite safes are made with thin steel walls and fire-resistant compounds like gypsum. However, what material is used to fireproof safes in this category is what determines their strength.

  • Fireboard safes

These safes are pretty cheap but still offer good protection against fire. Fireboard safes are also very portable, considering they are lightweight. You can relocate the safe relatively easily.

As the name implies, these safes come with several fire-resistant boards installed within the wall cavities.

  • Reinforced fireboard safes

These safes are the same as fireboard safes but reinforced with an extra-thick steel shell for extra anti-theft protection. Because of the thick steel shell, it is the least performing when it comes to fireproofing.

Steel conducts heat quite easily, giving you less time to put out the fire, unlike the other two. Because of the steel shell, this safe is heavier.


Fireproof safes come with different levels of fire resistance. This is why you must ask yourself what material is used to fireproof safes?

Once you grasp the concept and get to know the best material, you can choose a safe from that basis.

If unsure of the level of protection it can provide, check its fire ratings and design. You can be sure that if the insulation material is gypsum, you have some of the best insulation on your safe.

Always go for a fireproof safe with independent certification and rating over those without to keep your valuables safer from fire.


Hi, my name is Robert Blair. I’m the chief editor of Best Safes Ever. Again I'm a home and gun safe expert in New Jersey. I worked under champion safecracker Jeff Sitar for many years and learned practically a lot about safes and how to crack them. I am still examining and researching daily different kinds of safes to help our clients as a physical security specialist.