Heat Treated Firewood

Last Updated on January 18, 2023 by Grow with Bovees

What is Heat Treated Firewood?

Heat-treated firewood is wood that has been heated up for a period of time.

This treatment process is done for a number of reasons, including getting rid of any wood eating pests or other insects that the wood may be infested with.

This is done to mitigate the spread of pests and insects through wood that may be transported across state lines or into national parks, as well as it being a certification process, required for the import and export of firewood across national borders.

Heat treatment standards have become more strict due to the ever increasing danger of new insect infestations, such as the emerald ash borer, that have been known to decimate entire majestic forests, devastating ecosystems.

Drying and treating firewood in kilns has become an integral part of transporting and selling softwood and hardwood firewood safely.

Heat Treatment Process

According to the United States Department of Agriculture, any wood that is heat treated needs to be heated to a core temperature of 140 degrees F for 60 minutes.

This is usually done in massive firewood kiln ovens, that heat the wood up and by way of facility sensors determine when the wood has been adequately hot for long enough.

Once the internal wood temperature of the wood has been at a certain core temperature for long enough, any pests residing within the wood should have perished. These elevated temperatures also stave off fungi and other pathogens that have low temperature tolerance.

This process is not to be confused with kiln-dried firewood, which has only been treated to reduce the moisture content of the wood.

This process does not certify pest-free firewood and can therefore not be counted as a heat treatment certification process. To heat-treat firewood, particular temperatures and periods of time need to be considered.  

We will be looking at some of the differences between kiln-dried and heat-treated firewood and the basics of firewood heat treatment a little later on.

How To Tell if My Firewood Has Been Heat Treated?

Sadly, it is not possible to tell if your wood has been heat treated or not, there are no tests that can be conducted at home to confirm this.

The best way to ensure that your firewood has been heat treated is to have a reliable supplier, as well as looking at firewood labels that specify whether the wood has been heat treated or is only kiln-dried firewood.

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You could take a moisture reading, but this would only be able to verify whether the wood has been dried in a kiln, which does not usually conform to the minimum standard required.

If you are really unsure, just have the wood treated again or just make sure not to move it over state lines, even when going on a camping trip.

This is dangerous and could potentially be very expensive in terms of being fined for transporting uncertified and untreated wood.

Kiln-Dried or Heat-Treated Firewood?

Very often these two terms are used as a description for the same process, however, kiln drying and heat treating firewood are two processes that have significant differences.

There are several similarities in the process of both kiln drying and heat treatment but the effect on the treated firewood and the end result are quite different.

This must always be considered when looking at the legal framework surrounding treated firewood in terms of transportation and commercialization.

Kiln-drying is used as a process by which the moisture content of the firewood is reduced to make it more suitable for burning and does not necessarily fall into the certified criteria for disinfected firewood.

Heat treated firewood, on the other hand, refers to certified wood that does not have any pest infestations. A certified heat treatment is usually also overseen by a qualified third-party entity and a certification test is conducted to ensure that the firewood is in fact safe and a compliance agreement can be issued.

Kiln-Dried Firewood

Kiln-dried firewood pieces  are often more desirable to the market as they burn uniformly and produce a lot less smoke when burnt.

This firewood is also cleaner and is easier to ignite, as well as causing less creosote build-up. Kiln-dried firewood wood is also considerably better than only seasoned firewood or green firewood and has a higher market value.

Firewood kiln operators will load the wood into firewood kilns, where it will be treated for up to two days with increasing ambient temperatures within the oven.

Once kiln temperature readings are able to drive most of the moisture out of the firewood and the optimal temperature is reached, the wood is ready to be sold. The oven will create firewood comparable to seasoned firewood.

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In some cases, this process could also be aligned with heat-treatment certification standards, but this is not guaranteed. If the kiln-operator has facility certification requirements and the efficacy of standards is reached, the wood may be labeled as heat-treated instead of kiln-dried.

Heat-Treat Firewood

The main reason, firewood is heat treated instead of kiln-dried, is to remove any unwanted wood/forest pests or pathogens that the wood may be infested with.

This has nothing to do with increasing the ambient temperature of the piece of firewood to achieve a certain dryness.

This is done primarily to prepare the wood for movement across state lines and for export to other countries, in this case it will need to be heat treated and certified accordingly.

During this process, the internal wood temperatures will also need to be raised to a certain core temperature, that is a lot higher than with conventional kiln-drying.

Firewood heat-treatment comes with the accompanying standard of pest and pathogen free firewood, which also makes it a better option for any fire, even though it might command a higher price.

Heat treated firewood will pop and crackle less than non heat treated firewood.

A Guideline to Certification Requirements

Due to increasing emerald ash borer quarantine areas, accompanied by increasing pest infestations across ecosystems, the minimum requirement for the safe movement of firewood has been on the increase dramatically.

Compliance agreements need to be in place for this reason.

Here is a good guideline for heat treatment requirements and other steps that need to be taken to acquire a successful firewood kiln certification and disinfestation of firewood.  

  • The firewood must be treated at an internal wood temperature of either 60 degrees Celsius over 60 minutes or 71 degrees Celsius over 75 minutes. These are the current heat treatment standards.
  • The storage of the treated wood must be at least six inches off the ground and must be covered. This will keep the wood safe from carpenter ants and termites during prolonged storage times.
  • The kiln that is used for treatment must have independent temperature thermocouples or internal temperature sensors that can record and monitor the internal temperature of the pieces of firewood placed inside the kiln as well as permanent temperature probes that measure the ambient kiln temperature. Make sure all the required firewood kiln probes are present.
  • Stringent records of the treatment process must be kept throughout the entire treatment process. Including run time, start and finish, and the exact time at which the desired core temperature has been reached. These time combinations are vital.
  • The readings must always be taken from the largest firewood piece.  
  • Strict labeling requirements are as follows:
  • Treatment schedule
  • Compliance agreement number
  • Contents description (unless packaging is see-through)
  • Quantity (measure or weight)
  • Manufacturers/packers/distributors name
  • Origin of firewood
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Please take note that this is only a guideline and may vary from state to state or depending on the type and quantity of wood sold.

There may also be additional guidelines that need to be taken into account when it comes to state parks and a national park.  

Conclusion of Heat Treated Firewood

Due to the increase of pest infested firewood and the threat it could pose to forests and ecosystems, local authorities have worked tirelessly to mitigate the spread of pests such as the emerald ash borer and other harmful insect threats.

The increased regulations in firewood treatment, particularly if you are in the firewood kiln business, or for a heat treatment facility has become more and more regulated.

The responsible movement of firewood is something everyone should pay attention to and firewood treatment should only be done by a certified institution.

If you are looking to heat-treat firewood as a business, make sure you consult with your local authority for exact information surrounding treatment requirements and the calibration of kiln temperature.  

If you are just looking at building a campfire or buying firewood for your smoker or barbecue, heat treated wood is always the best option.

It is dry wood that burns easily and cleanly and is safe to keep inside the house. If you are looking at storing your wood for a longer period of time, it is definitely the safer option, as it will be free of termites and other insects that may damage your property if left unchecked.

Your bundle of firewood may be infested with these critters as you are buying it.

When in doubt, just check the label on your firewood bundle. If it says heat treated firewood, it usually means all the treatment requirements have been met and the firewood is safe to move, keep and store.