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wood stove

Emergency Ordering

You need wood in the next 24 to 48 hours. We will do everything (safely) within our power to deliver.

2022-23 Season

Tell us how many cords (minimum 2 cords), diameter, length and kind of wood you need.

Campfire Wood?

We'll can deliver wood to your remote cottage, cabin or your campsite. (delivery charges after 20 kms)

How Does Wood Burn?

The following topics are covered:

  • Ignition and combustion of wood
  • Fire performance of wood
  • Heat release and fire spread
  • Charring
  • Smoke production and toxicity

Ignition and combustion of wood

Many materials in our environment, including wood products, burn “indirectly” in the sense that the materials do not actually burn, but combustion takes place as a reaction between oxygen and the gases released from a material (an exception from this rule is the glowing combustion of charred wood where oxygen reacts directly with carbon). Under the influence of heat, wood produces easily substances that react eagerly with oxygen, leading to the high propensity of wood to ignite and burn.

Ignition and combustion of wood is mainly based on the pyrolysis (i.e. thermal decomposition) of cellulose and the reactions of pyrolysis products with each other and with gases in the air, mainly oxygen. When temperature increases, cellulose starts to pyrolyse. The decomposition products either remain inside the material or are released as gases. Gaseous substances react with each other and oxygen, releasing a large amount of heat that further induces pyrolysis and combustion reactions.

Depending on environmental conditions (such as temperature, oxygen concentration, moisture, fire retardants, pH etc.), the pyrolysis of wood can proceed mainly on two pathways presented in Figure 2a. The tar forming pathway, taking place in a temperature of approximately 300 °C, is related to the “normal” burning of wood. In this case, pyrolysis produces a lot of tar including levoglucosan that decomposes easily into burning gases under the influence of heat (see Figure 2b). Thermal decomposition can take place also through char forming pathway. In this process, cellulose is first transformed to unstable, “active” cellulose that further decomposes so that reaction products are mainly carbon dioxide and water, and the “backbone” of cellulose containing a lot of carbon.

Fire performance of wood

The reaction-to-fire properties, such as ignitability, heat release and flame spread, are most relevant for fire retardant wood products. Charring as a fire resistance characteristic property may also be influenced especially by surface protective layers.


In order that wood can ignite, its temperature must rise so high that pyrolysis takes place strongly enough and the chemical reactions of combustion start. Therefore, the ignition of a wood product is dependent on the way of heating, that is, the thermal properties of the material, and the way of heat attack on the material.

The factors affecting the ignition of wood are well known in general: wet wood is difficult to ignite, thin pieces of wood ignite more easily than thick logs, and light wood species ignite quicker than heavy species. External factors having an influence on ignition are the intensity of heat exposure and its form of effect (e.g. the distance of flames from the surface).

The moisture content of wood has an effect on ignition mainly as a heat sink. Heating-up of the water and especially its vaporization consume heat energy. In addition, moisture increases the thermal inertia of the material.

The ignition of wood products with different thicknesses is dependent on their thermal thickness. A thermally thin layer ignites more quickly than a thermally thick material. When a thermally thin product is exposed to heat on one side, its opposite side heats up very close to the temperature of the exposed side by the time to ignition. In the case of a thermally thick product, the opposite side does not heat up but remains at the ambient temperature when the specimen ignites. The thermal thicknesses of practical products fall between thermally thin and thick. As a rule of thumb, a wooden product is thermally thin if its thickness is not more than a few millimetres, and thermally thick if its thickness is of the order of 10 mm or more.

Heat release and fire spread

Heat released in combustion is the driving force of a fire: the larger the heat released by a burning object is, the faster the fire spreads and the hotter the gases and limiting surfaces of the fire enclosure become. Thus, one of the most essential quantities describing the burning of materials is the rate of heat release, denoted with  and expressed in kW or MW.

In addition to the internal structure and properties of a material, the rate of heat release is strongly dependent on external factors. Therefore, exact  values for different materials cannot be given. The most important external factors having an effect on  are the net heat flux  to the surface and the oxygen concentration of the ambient, described with the factor f(O2). The internal properties of a material affecting on   are the heat of combustion ∆Hc, the heat of gasification Lv, and the specific heat capacity C.

When wood burns, flames spread on its surface. Flame spread can be regarded as a sequence of ignitions. Therefore, flame spread is governed by the same factors as ignition. The heat released by a burning area has an effect on flame spread rate, directly by the flames and through the warming-up of the fire enclosure. Thus, the factors governing the rate of heat release are essential also for the flame spread.

Yarmouth Firewood for sale

Emergency Ordering

You need wood in the next 24 to 48 hours. We will do everything (safely) within our power to deliver.

Fall 2020 - Pre-Order Now

Tell us how many cords, diameter, length and kind of wood you need.

Campfire Wood?

We'll deliver wood to your cottage, cabin or your campsite.