Can Rubber Mulch Catch On Fire

Can Rubber Mulch Catch On Fire? + [How To Prevent It]

Having heard about rubber mulch fires, you may be left to wonder if it’s still safe for use in your home for playgrounds. What could have caused rubber mulch fires and are there measures you can take? Is it even true that rubber mulch catches fire?  

Can rubber mulch catch on fire, therefore?

Though rubber mulch isn’t naturally a fire hazard, it does catch fire. Once exposed to an open fire source it ignites to high temperatures that are difficult to put off. However, unlike wood mulch, it doesn’t combust spontaneously. 

In this article, I’ll discuss in detail if rubber mulch can catch on fire, the possible causes, and how to put it off. Also, I’ll discuss the measures you can take to prevent mulch fires. 

Read on.

Can Rubber Mulch Catch on fire?

Yes, rubber mulch can catch on fire. A common myth is that it’s non-flammable. Unfortunately, this is untrue.

Needless to say, it’s one of the most aesthetic mulches in place, but flammability concerns are valid.

Whether it’s crumb rubber or rubber mulch, the fact remains that the product is rubber. Even so, it’s not easy to ignite compared to wood mulches; it eventually catches fire if there is an open-source.

What’s important to note is that most rubber mulches ignite at 260 to 316 degrees Celsius (500 to 600 degrees Fahrenheit). Meaning it’s not easy for it to ignite. The main reason is, rubber is heat resistant and a not-so-good thermal- conductor. Hence it does catch fire but not easily.

The rubber mulch needs an open flame such as a propane torch or a lit match to light up. However, since it still burns up, rubber mulch might not be a good option if you reside in a fire-prone area.

Even so, studies confirm that the chances of igniting rubber mulch from a carelessly tossed cigarette are next to nil.

Is Rubber Mulch Fire Resistant?

No, rubber mulch isn’t fire-resistant. According to the Journal of Arboriculture, rubber mulch ignites when exposed to a propane torch. The study further confirms that fire-resistant mulches include shredded hardwood, cocoa shells, and pine bark nuggets.

While it’s not easy to ignite, it’s hard to extinguish once it lits up. Furthermore, if it’s in close proximity to your home, the fire can easily spread to your house.

It’s essential to take precautions, but accidents are still bound to happen.

In fact, there are thousands of fire mulch cases every year, especially during summer. Although most can be easily extinguished, they usually spread quickly to shrubs and nearby structures if left unchecked.

Consequently leading to costly losses and, at times, deaths.

So, if your mulch occupies a large area, it might be wise to have a fire protection cover.

Also, there are several measures to take to avoid fire occurrences on your rubber mulch.

Safety Measures To Prevent Fire Rubber Mulch Fires

  •  Keeping open fires away from the mulch
  • Maintaining at least 6 inches between the mulch and any combustible structures. It could be houses or shrubs.
  •  Ensure you follow manufacturer instructions when installing electrical devices such as decorative lights.
  • Try to keep your rubber mulch moist
  • Don’t install your rubber mulch deeper than 3 inches.

Can Rubber Mulch Spontaneously Combust?

Fortunately, rubber mulch cannot spontaneously combust. Spontaneous mulch combusting happens when heat builds within the mulch that is layered. It could be 6 inches layering or more. Apparently, when heat builds up within the layers, it causes smoldering and hence a fire ignition.

Although not thoroughly tested, some research has confirmed that some mulches spontaneously combust when exposed to certain conditions. But, it’s good to note that this isn’t a common occurrence in any type of mulch, and no findings confirm that rubber mulch can spontaneously combust.

However, the University of Nevada did a study on eight different mulch fires, seeking to confirm the most combustible mulch. 

Their findings were as below;

The research concentrated on the flame height, rate of speed, and temperature. Rubber mulch had the highest flame and temperature while pine needles and shredded western cedar topped on the fire speed.

Is Rubber Mulch More Flammable Than Wood Mulch?

No, rubber mulch is not more flammable than wood. This is because it’s not easy to set rubber mulch on fire compared to wood mulch.

In spite of that, a consumer reports study confirms that rubber mulch burns faster and hotter—thus creating a severe fire that is difficult to put off compared to wood mulch

So, if you’re looking to purchase either of the two, it’s important to consider your area of residence. Regardless of whether they are long-lasting, neither is suitable for fire-prone areas.

Nevada University report confirms that composted wood chips and Tahoe chips in a single layer, Tahoe chips with fire retardant, and Tahoe chips with 2-3 inches deep are the least flammable.

You can also opt for rocks, granite, or decomposed granite as non-flammable options too.

How Do You Put Out A Rubber Mulch Fire?

Using dirt or sand is usually the best approach to out-putting rubber mulch fires.

Putting out a rubber mulch fire can be challenging as with any other rubber fire, mainly because the properties that process it are highly flammable.

When you try to put off a rubber mulch fire with water, the fire might temporarily go out. But due to its poor thermal-conducting nature, the water won’t cool the rest of the rubber; instead, it continues burning (unseen).

Later, once you stop spraying the water, the heat from the initially not lit side ignites the side put off.

Due to this, extinguishing rubber mulch with water might not be the best approach. If you choose this route, it might take several days to stop it fully.

Sand or dirt works better as it cuts off oxygen from the fire. Still, even with the use of sand or dirt, it might take longer to put off rubber mulch fires.

In addition, to curb the fire, ensure you separate or put a barrier on the lit part from the section that is yet to light up. You can do this by wetting the area that is yet to catch fire or, if possible, putting a rock barrier between the two sections.

Always remember before anything else to put on protective gear. Rubber mulch smoke is toxic, and of course, you still need protection from the flames.

However, if the fire is widely spread, reach out to the fire brigade.

Does Rubber Mulch Fire Get Too Hot?

Yes, rubber mulch fire gets extremely hot. They burn with great energy value, as with all rubber fires. As research confirms, its fires produce the highest temperatures among the tested mulches. 

Relatively, its melting point is between 260 to 360 degrees Celcius (These are the temperatures it needs to light up). It also produces a heavy flammable vapor when it reaches approximately 280 degrees Celsius. Consequently, the vapor might get trapped in the molten rubber mulch and in return, catch fire leading to an explosion.

What’s worse? Rubber mulch-based fires can burn for days or even months, mainly if occupying a large area.

In addition, it releases a heavy dark smoke that hangs in the air for long durations. This smoke contains several toxic air pollutants that are of great danger to the environment.

Further, the smoke comes with fine particles that make it particularly easy to inhale. If you get directly exposed to it, it might lead to respiratory issues and even chronic illnesses. Vulnerable people are at most risk, such as those with pre-existing health conditions like asthma, heart diseases, pregnant women, and anyone above 65.

Moreover, once released, the smoke is also dangerous to the environment as it carries chunks of carbon monoxide. Studies prove that this kind of smoke plays a significant role in the current climatic changes and global warming.

Always ensure you wear protective clothing when handling any kind of rubber fire.


Is Rubber Mulch A Fire Hazard?

Not really. Compared to wood mulch, rubber mulch is not as easy to ignite. However, once it does, it’s not easy to put off

Its fires have also been confirmed to have extremely high temperatures, and its smoke carries toxic properties.

Are Rubber Mulches Fires Common?

No, they aren’t. This is mainly because igniting rubber mulch is not easy. However, you will experience fires if ignited through an open fire source.

Therefore, it would be best to always take precautions as they do happen.

Bottom Line

By now, you are enlightened. When answered with no bias, the question “can rubber mulch catch on fire?” is straightforward.

As discussed, it can ignite. So, the current notion that is doing rounds that it doesn’t burn is nothing but a myth.

Even though it has countless pros, we can’t ignore the negatives. Regardless, when it comes to catching fire, it’s clear its chances are on the lower end of the bargain compared to wood mulches that can combust spontaneously.

However, most people can agree that all mulches available have their fair share of disadvantages.

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