Concerned about chemicals

Hello, I just found your site and found it to be very informative, however I do have a concern that hasn't been addressed. My husband and I have recently purchased our first home. This is also the first time either of us has had a fireplace. My husband saves pallets from work, breaks them up and burns them in the fireplace. He also burns any wood he can find, from pruned bushes, trees etc. I am concerned with the possibility of chemicals or poisonous fumes from some of this unconventional 'firewood'. Can you please give me some information or refer me to a site that can help?


You should only burn clean, uncoated, non-salt-laden, untreated wood. Shipping pallets are usually fine and prunings are fine too. Don't burn painted, stained, creosote treated wood or wood that has been pressure treated with preservatives (these usually tint the wood green or brown). Despite some people's enjoyment of "that nice woodsy smell" when wood is burned in a fireplace, you should never smell wood smoke in your house when the fire is on. If you can smell smoke, get a professional sweep or installer in to check it out and advise on how to stop it.



Kevin says don't burn pallets

I was reading your questions and answers archive and noticed the one about it being okay to burn pallets. I was burning pallets last year until my research revealed that most shipping wood is treated with one or more of the following: fire retardant; insecticide; fungicide. The arsenic treatments were easy to spot being green; now copper compounds are used. Insecticides are not easy to detect. Fire retardants result in a brownish or rust colored stain. I have noticed that sometimes even stickers (for under bunks of lumber) are treated. I thought that I had discovered a gold mine when I saw pallets for countertops made of 4x4 oak 10' long with 3' cross members, until I saw that telltale brownish stain. I was heartbroken! In other words, err on the side of caution when selecting shipping wood.

Kevin, December 27, 2004


More on pallets from Mike

I read with interest one of your visitors comments on burning pallets. I have worked in the wood industry for almost 30 years and have sold many pallet manufacturers. I believe that the use of treated lumber in pallets is a rare occurrence. The pallet industry is a down and dirty price sensitive business because the product being manufactured is generally a throw away. I think with a little more research you will find that the main anti-bug requirement for pallets and shipping crates would be heat treating and not chemical treatment. Hard wood doesn't take treatment well anyway. Mostly southern yellow pine is a used in treating. Even new requirements for export require heat treated verification to prevent bug infestation. The greatest opportunity for chemicals on pallets comes during their use, not manufacture.

Mike, October 8, 2005

Interesting discussion. I can't comment because I live surrounded by trees that need to be cut, so there's no shortage of wood, and I don't come across pallets.



No question, no answer, but good ideas from George

I'm sort of a tree-hugger. I love trees. But, I just don't understand the enviro-wackos that think you shouldn't burn wood for heat! Burning wood for heat simply uses what nature wastes. Here are some tips I've found to find sources of wood.

If a tree is going to be cut down anyway, why bury it to leave it to rot in the ground or lay off in a ditch to rot. The greenhouse gases that are produced are the same. Actually, if you do it right, you'll produce less greenhouse gas if you burn it in the stove!

I don't "harvest" trees for my wood. I find somebody that is cutting down stuff anyway and ask them if I can help them haul it off to my woodpile! After all, its a burden for them to trash it anyway. In fact, I've got a couple neighbors that routinely dump 8-12 inch "trash" trees on my woodpile. They just appreciate a place to get rid of it instead of taking it to the dump!

Another thing I've found out: there is enough wood on the ground in the 8 or 10 acres of woods that I own to last me about 2 years. By then, there will be more. I call this "Let God do the whacking!" Not only that, there doesn't seem to be a lot of people willing to flex their back to get wood. I see 100s of tons of wood laying on the ground producing Co2 and no good being received from it. Ask a landowner if you can clean out the dead wood in his woods. I'm betting he'll come close to paying YOU for it!

Follow the loggers: Loggers only use half the tree!!! If you see logging equipment someplace chances are you'll find easy pickings! Ask the landowner for permission to help clean up after the loggers. (some of them make REAL BIG messes!) I've got a father in law and a cousin that just had their places logged. I also have a friend who raises Christmas trees and is cleaning out his fence rows. Between the three, I'm just set for wood for the next 5 years!

My dad and I both burn wood for a good portion of out heat. I supply about 30% of mine. My dad is probably 80%. I keep hauling wood in on my trailer (I cut it in 4-6 foot lenghths and haul it in). If I keep hauling it in, I don't know if I'll be able to burn it all! Maybe I could solicit some help!!!



Newspaper Logs

Hello , I am looking for a formula (liquid) for log newspapers. Saw this years ago but can't remember where. Some one sent me one on the internet:

  • 4 lb. copper sulfate -- this stuff is $12 a pound (!!!!)
  • 3lb. rock salt
  • 1 gal water

You dissolve the copper sulfate & rocksalt in the water, wet the newspaper and roll it set it aside and let it dry. But I sure can't afford it. Do you have any suggestions?

Thank You, Papa

Hi Papa,

Yes, I have a suggestion: Burn natural firewood or commercial firelogs only.

Newspaper logs, particularly using the copper sulfate and salt concoction you mention, would give off toxic emissions certainly laced with dioxin, since dioxin is produced during the combustion of organic material, especially in the presence of salt. Dioxin is a persistent, bioaccumulating toxin. You don't want dioxin emissions in your neighborhood.

Ideally, newspapers should be recycled to produce more newsprint or other products. It should not be burned in quantities larger than needed to get a fire started.



Throwing versus stacking firewood

I get a pile of wood delivered. If I throw the wood into my shed instead of stacking it how much loss of capacity will I get. I think I would rather build a larger shed then stack wood year after year.


Excellent question, Dan.

The question is, what percentage is air space of a stacked versus thrown cord. I know that the air space in a stacked cord varies from 25 to 50 percent because I researched it a few years ago for a project I was working on. The average for firewood seems to be about 35%. I haven't seen a number quoted for the air space in a thrown pile of cut, split firewood, but I can tell you this: The amount of firewood stacked carefully in the back of a pick up truck up to the level of the sides is about the same as the amount the same pick up can hold if the wood is thrown in until pieces start to fall out. I would think that means thrown wood would take up at least two-thirds more space than stacked wood.

The real problems I see in throwing wood into main storage are:

  • beating the hell out of the floor and walls
  • unable to form vertical walls to take up the space efficiently
  • an unstable pile as the wood is removed bit by bit
  • poor drying due to monolithic pile instead of rows with some space between

On the other hand, if an extra large shed is no problem, your thrown pile might save some work. However, I would strongly recommend that you store the wood stacked neatly outside for the summer to dry before you throw it in the shed. Otherwise you could be burning wet wood next fall.



Identifying firewood from sustainable sources

Every one of the firewood suppliers in my area I asked said (once they understood the question) that their wood was from a renewable source. This seems very unlikely. Do you have a list of firewood suppliers who you know are from sustainable source? Do you have any other suggestions (besides cutting the wood myself) to help me source this type of supplies. I am in the Toronto, Canada area. Any suggestions would be appreciated.

Thank you. Malcolm

Hi Malcolm,

Many of us who buy part or all of our firewood supply share your concern about the sustainability of the source. One of the biggest problems is in defining the word sustainable in the context of forest management. The large forest products companies, supported by the government, claim that huge clearcuts are sustainable even though the entire landscape is permanently altered. In our environment section is a paper that deals in part with this issue. Following is a relevant quote from the conclusions.

"An increase in the use of wood as a fuel for residential heating can occur within the framework prescribed by current principles of environmental sustainability. This framework could be generally described by the following points:

  • The integrity of the forest, including the trees, the soil and the site, is maintained.
  • Species diversity within the managed forest is maintained or enhanced.
  • The requirement for the use of non-renewable fossil fuels is reduced, resulting in reduced concentration of greenhouse gases in the atmosphere.
  • Air shed pollutants are minimized and those that are released do not produce health impacts on the population.
  • The latter item may require regulatory limitations on some forms of residential woodburning in densely populated urban areas and in areas with poor airshed ventilation."

A large part of the hardwood fuel produced in this area is a byproduct of forestry operations that yield materials for furniture, flooring and other products. Various trade agreements and buyer requirements have resulted in sustainability certifications for forestry operations, so the byproducts can also be considered to be from a sustainable source.

The rest of firewood on the market is taken from privately-owned wood lots. Each site and each cutter are unique so I am not able to make a sweeping statement about the sustainability of either source. I have seen private forests that yield a lot of firewood every year and have been doing so for decades. I have also seen near-clearcuts in hardwood stands on private land. Part of the problem we all face in trying to take responsibility for our fuel supplies is that an environmental consciousness has not emerged so when you ask about sustainably produced firewood, you may get a blank stare from the supplier. You face a particular problem in that you are looking for sustainably produced firewood in Canada's largest city.

Several years ago those of us who formed the Wood Heat Organization gave serious thought to trying to organize a sort of firewood certification program so that suppliers who paid attention to sustainability could use the logo of a credible organization to inform the public of their commitment. But organizing firewood suppliers is something like herding cats. Our experience was that most suppliers like to keep their business private and are suspicious of anyone who talks about messing with it.

I'm sorry that I don't have a definitive answer for you on this.  But you have made the first step by asking your suppliers about sustainability. Only if they feel the pressure to take some environmental responsibility for their product will they put pressure on those who supply them and so on up the line. To some degree, the availability of sustainably produced firewood depends on buyers demanding it.



Fuel cost comparisons: price versus value

My family lives in a house that has a furnace that can burn fuel oil or wood.  I want to know which is a better buy.  If one converts the prices of each into cost per BTU, would this tell me how much one can pay for wood?  Thank you. Darwin

Hi Darwin,

We learned a long time ago that calculated cost comparisons between wood and other options are a waste of time. First, none of them are very accurate because of all the variables involved in wood heating.

But ultimately it comes down to a distinction between price and value.  For example, if I heated with a furnace I would want a very large price difference between wood and oil to make up for all my work in dealing with the firewood.

But for me, more than half the value of wood heat is spending my time in front of a beautiful hearth watching a spectacular fire and feeling that radiant warmth. Those aspects might make wood heat worth it even if the price were almost the same as oil.

If many people in your community heat with wood, there is a good chance that firewood is competitive with oil.  If not, it is doubtful.  Ask around to see what people pay for their wood and where they get it.



Comparing fuels

What is the btu comparison of a pound of coal to a pound of Rock elm to a pound of Balsam.


The energy content of a pound of wood, regardless of species, is about the same. The difference in species is mainly in their density. So a pound of rock elm would have roughly the same energy content as a pound of balsam, but would be phyisically about half as large. The only table I can find with such comparisons has them in metric values. You can convert them.

  • Anthracite coal : bulk density: 880 - 960 kilograms/cubic metre; calorific value: 32 megajoules/kilogram
  • Softwood : bulk density: 275 kg/cu m; calorific value 16 - 20 MJ/kg
  • Hardwood : bulk density: 576 kg/cu m; calorific value 16 - 20 MJ/kg

Note that these variations do not indicate the efficiency or effectiveness of these as fuels.



Science experiment: measuring heat of different woods

How can I measure the amount of heat produced by different types of wood - for a science experiment at school.  I know you list the amount of heat, but I have to show how I measure it.

Thanks, John


Believe it or not, but measuring the heat output from the burning of wood is a terribly complex and expensive thing to do. The labs that do emissions and efficiency testing for wood stoves cost about $100,000 to put together and a complete set of tests costs the manufacturer about $10,000.

The difference between different species of wood is almost entirely a difference in density. That is, all species of wood have about 8600 BTUs per pound. Hardwoods are dense and softwoods are less dense, but pound for pound the energy content by weight is about the same. So, if you carefully conditioned your samples to the same moisture content, then weighed them carefully before burning them, you would probably find very little difference in heat output between them.

I don't have a good suggestion for a simple heat output measurement technique. Sorry.



A kindling question

What's the most effective way to split logs for kindling? Any hints on tools and techniques to make the job easier?


Hi Doug,

I have a very nice kindling maul, like a miniature version of a splitting maul.  It has a handle maybe 14" long and the head weighs 2 or 3 pounds.  It works great. Check stove and fireplace shops.  These used to be very popular.  I haven't seen one for sale recently, but then I haven't been looking.



How about willow as kindling?

I'm wondering about drying and using willows in my fireplace as kindling.  Is the wood too soft and will it put out too much creosote?  I have been  unable to find this information on the internet anywhere else.  If you can  answer this, I'd much appreciate it.

Thank you, Roni


I have never tried willow as kindling, but I can imagine it being just fine. Softwoods generally make the best kindling because the low density means the wood has a lower heat transfer rate, which means the spot that heat is focused on heats up to ignition temperature quicker than if it were denser hardwood. The key with kindling is to make sure it is very dry. Regarding creosote, don't worry about that too much in kindling, since you don't use much and it is burnt quickly. I use cedar as kindling and it is an oily wood. The oils make it a terrific kindling wood because they make it a more volatile fuel. I doubt if willow is as oily as cedar, but I could be wrong. You won't find much detail on such matters on the web because species and fuelwood management varies regionally.  But, there is certainly no harm in trying the willow if that's what is available.



I need info on the efficiency of different woods

Could you please send any info you might have on the burning efficiency of different types of wood.  Your help is greatly appreciated.



The process of burning wood in a batch in a stove, furnace or fireplace is such a random event and since there are so many different kinds of appliance types and combustion systems, and since moisture contents and even the density of a single species grown on different sites varies a lot, there is no way to generalize on such things. Hard woods burn longer and produce harder, longer lasting coals just because the original wood was denser than softwoods.

In terms of precision, that's about as good as it gets.  As we point out on the site, it is much more important to have properly cut, split and seasoned firewood than it is to worry too much about the species.



Question from a novice wood burner

My question is this: I just purchased a new woodburning stove from Avalon that is sitting in my existing inefficient fireplace and take great pleasure in burning wood now. The only concern is that I am not sure what kind of wood that I am getting from some people that I have called to supply me. Where can I get information either from the public library or internet to help me identify different tree species by their bark.  I have looked all over the internet where I thought I could find information and there seemed to be none out there.  Please help me with this concern if you can.

I really enjoyed your site.  One other question: Can I burn ironwood on a continual basis.  I heard this wood is really good for high BTU values.

Thank you for your help.


Your local library, book store, government forestry agency, or university extension service would probably have publications that could help you identify tree species. In general, though, hardwoods are dense and heavy, even when seasoned, and softwoods are not.  You can sink your fingernail into very soft woods, but it would hardly make a mark in very hard woods.  Because they are denser, hardwoods last longer in the fire and produce a longer lasting coal bed. But softwoods can be very pleasant to burn and can do a fine job of heating a house.  You would use a greater volume, but not necessarily more weight of wood if you burned softwoods. The bottom line is that properly cut, split and seasoned wood is best, whatever the species. You might ask around locally to see what experienced wood burners are burning.



Is jackpine too hot for my stove?

My question is whether "jackpine" is too hot for my Oborne 1600 woodstove. One person said that it would "burn out" my firebox. We like and have used birch with little ash and good longevity. Birch is my preference aside from availability and cost. Jackpine is certainly right up there for aroma and ease of lighting. Spruce sparks and is usually knotty. Any  comments?

p.s. I live in east central Alberta. Best regards, Bob


Don't worry about jackpine burning out your stove.  It is a controlled combustion stove which allows you to prevent overheating. That is, heat control is up to you and not to the wood. The person advising you is just about 30 years out of date in their thinking. A mix of jackpine and birch will work fine, provided the wood is cut, split and seasoned right.



Can I burn scrap pine lumber?

Hi, I have a chance to get scrap 2x4 pieces. Can I burn these safely in my fireplace insert?  Since they are pine will they gunk up my chimney?

Awaiting your reply.   Thank You, Sara


Go ahead and burn the lumber, provided it is not painted or treated.  The pitch that people associate with creosote is in the pine or spruce bark, but of course, your lumber will have none of that.  As long as you maintain bright flaming fires in your insert, you won't gunk up your chimney much faster, if at all, than with other wood, but you should check the chimney periodically to be sure.



Can I burn Cedar?

Can you safety burn cedar wood? We just cut down several cedar trees and were wondering if it is safe to burn.



Sure you can burn it, but it depends on what you burn it in and how you go about it. Cedar makes just about the best natural kindling you can get. It splits easily, lights easily and burns hot. It also spits and crackles so it is not good in an open fireplace.  Also, if you are burning it in an open fireplace, you might find it doesn't last long. If you burn it in a stove, you might find it makes a smoky fire if you turn down the air. The thing is, when heated, cedar releases its combustible gases (smoke) very quickly, so it needs a lot of air during its peak release period. Cedar works well for quick fires in spring and fall to take the chill off.

My attitude is there is no bad firewood except wet stuff and logs you can't split. Most of the rest depends on how you use it.



Using pressed logs

Dear woodheat,  Could you please inform me on the benefits from using manufactured pressed logs? They seem to last all night, and aside from the cost, they are convenient to use (no bugs, not wet, and last forever). I live in Vancouver BC and use a log that is manufactured here that is 100% wood and harder than oak. I would never go back to cord wood!  I don't see anything on your site about this side of heating with wood. Why not?



Although I haven't seen a detailed price analysis, partly because prices vary in different market areas, I doubt that heating with manufactured logs would be competitive with oil, gas or even electric heating. These logs are most often used in fireplaces to create ambience, not for heating purposes. Since our web site is devoted to wood heating, manufactured logs have not been a high priority for site content. But I think a discussion of manufactured log use would be a good addition to the site.

Research has shown that 100% sawdust compressed logs and even wax impregnated logs actually burn cleaner in a fireplace than cord wood, so they are a good idea in urban areas. Note that part of the higher price you pay for a manufactured log is the energy consumed in drying and compressing the sawdust, the the petroleum in the case of wax logs, so you are in fact burning some embodied fossil fuel (in most cases). The product, therefore, is not as renewable a fuel as natural firewood. Every fuel has its advantages and disadvantages. Since you live in Vancouver, which has some serious air quality issues, you are probably doing the right thing by burning manufactured logs.