The Real Cost of ‘Free’ Firewood

logs on the ground

As the overall cost of heating our homes continues to rise, some people think that getting their hands on some free firewood is a sure-fire way to save a few pennies. In fact, foraging for fallen logs or in some cases even rooting through skips for discarded furniture or construction wood is something of a sport for many. We’ve spoken with customers who had gained a real sense of satisfaction from this, feeling smug and somewhat triumphant to have heated their home for ‘nothing’. But is this really the case? As the old adage goes, ‘there’s no such thing as a free lunch’, and this certainly extends to firewood too! Here are just some of reasons that free firewood usually comes at a cost:

Efficiency costs

Undried, foraged wood will contain up to 90% moisture. When burning this type of wood much of the energy is used simply by vaporising this water. It has a similar effect to adding a large jug of water to a lit fire and will mean that the resulting heat output is extremely low, very unlikely to be any more than a measly 1kWh. This is certainly not enough to provide effective heating for your home leaving your central heating to do the heavy lifting!

Health costs

First off, not all types of wood are suitable for burning at all – the wood from conifers, pine trees and larch for example contain a high quantity of sap which will spit, produce large amounts of smoke and smell quite unpleasant. Similarly, disused construction wood usually contains additives and treatments that were designed to stop the wood from rotting or pesticides to prevent woodworm and these can result in unpleasant and polluting emissions that can even be toxic.

Environmental costs

As well as being extremely inefficient to burn, wet wood (defined as wood with a moisture content that is greater than 20%) contributes to air pollution because its combustion releases smoke and other pollutants into the environment. In fact, burning this type of wood as opposed to properly dried, ‘ready to burn’ firewood could actually be banned as part of a government drive to tackle air pollution.

Maintenance costs

Burning wet or certain types of treated wood causes creosote and other types of sooty deposits to build up in your flue or chimney. At best, this will generate added maintenance or premature replacement costs, often invalidating the warranty on your wood-burning stove. At worst, these deposits can even cause a significant fire hazard.

Hidden costs

Firewood can provide a home for all manner of insects and fungi. In particular, firewood acquired from trees that have already died is more likely to contain wood-boring insects whose purpose in the ecosystem is to invade and recycle dead wood. These creepy-crawlies usually hibernate during the cooler winter months, but the warm, indoor environment of your home can bring them to life causing infestation and its associated damage. This can be both difficult and costly to eradicate.

Last but not least, in collecting ‘free’ wood you could actually be breaking the law! As far as UK law goes, all trees are owned. Even the trees located in public woodlands are likely to be owned by the Forestry Commission. It is an offence to help yourself to wood without the consent of the owner.

So, all in all, it’s pretty clear that what many people consider to be free firewood often comes at a cost. So, what’s the alternative? Our advice is to use kiln dried logs. Their low moisture content of well under 20% means that kiln dried firewood is much more efficient, cleaner to burn, easier to store, contains fewer pollutants and in light of their overall efficiency vs. overall cost are often easier on the pocket too. What’s more, the kiln drying process eradicates insects and fungi which will ensure you don’t welcome any unwanted house guests.

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