What? How can mulch set a house on fire?
When I first read this story in the news paper http://avon-oh.patch.com/articles/mulch-spontaneously-combusts-sets-house-on-fire, I thought to myself, “No way. Mulch, spread out in a flower bed, is not deep enough for it to spontaneously ignite. I realize that any organic material that is moist, piled high and compacted will heat up inside the pile and possibly catch fire due to spontaneous combustion.
It has long been known that green hay stacked in a barn can heat up and burn down the barn. It’s not unusual for large piles of mulch at saw mills and mulch yards to heat up inside the pile and catch fire. If you’ve worked with mulch you know that the mulch inside of the pile can be so hot that you can’t touch it. But in all of these scenarios the piles are large, damp, and have no air circulation inside the pile.
It’s also not at all unusual for mulch along roadways, driveways, and outside of the entrances to public buildings such as restaurants etc. to catch fire from a flicked cigarette butt. It happens all the time.
But when the fire officials investigating this house fire stated that the mulch in the flower bed of this home caught fire via spontaneous combustion I thought to myself; “That’s impossible! Mulch in a bed is only a few inches thick and there is no way in the world that it could possibly heat up enough to catch fire.” I just knew they were wrong about this.
But I could be wrong about that.
I did some research on spontaneous combustion and it is reported that even though nobody can really explain how or why it can happen, brush fires have been started via spontaneous combustion when things as simple as a grassy field catch fire for no apparent reason and it’s considered spontaneous combustion because there is no other apparent source of ignition. Hmmmmm??????
So. . . even though I still have my doubts about these house fires, I do have a theory or two if in fact these fires that started in the mulch are the result of spontaneous combustion. It was really, really dry for several weeks before these fires started and it was extremely hot that day. The mulch was as dry as dry can be, especially at the surface. Mulch is made up of larger and small pieces, with some strands being almost as thin as human hair. I suppose, just guessing now, that if the sun were to shine intensely, as it does when you hold a magnifying glass in the sun, those really fine strands of mulch could ignite under the intense rays of the sun and that would be enough to ignite the rest of the mulch in the bed.
I honestly don’t know.
But if you are concerned, just don’t let your mulch get that dry in areas where the sun beats down. In this situation it had been really, really dry before those fires started.