Having a wood burning stove, an open fireplace or a hydronic heater that uses the energy from burning wood to heat water for use in the home, is an ambition for many permaculturists. Such methods of heating and cooking are typically more environmentally friendly than electric or gas appliances, often more efficient at fulfilling their task, and add a certain charm to the home. Plus, if you have a lot of trees on your permaculture site, you can create a closed system of energy production, using timber from your plot in your home, so you do not need an outside source to complete the cycle from input to yield. However, even if you get your firewood from another source – one that is local, sustainable and has not treated the wood with any inorganic chemical compounds – wood burning appliances are still better for the planet and also likely to cost you less than conventional appliances.
One of the things about firewood is that it is – if harvested sustainably – fairly seasonal. Trees are typically pruned or harvested in the fall and winter to allow regrowth or the growth of new trees to occur the following spring. This means that those sourcing wood for their appliances will have a glut. To ensure that the wood you attain during this period is available for use throughout the seasons you need it (which could be into the spring if you live in a cold climate) it is important to store it correctly. By storing your firewood in the correct way you dry it our and keep it dry so you can use it when needed.
Wood that is freshly cut – sometimes called ‘green’ wood – it contains a lot of moisture. Some wood can be as much as 100 percent water – meaning that half the weight of the wood is moisture. To burn properly and efficiently, the moisture content in the wood needs to be at 20 percent or below. As a general guideline, to get a freshly cut piece of firewood to this moisture level takes six months, assuming it is correctly stored and not exposed to extra moisture. So preparing you firewood in the winter, you ensure you have sufficient time for it to dry before the cold weather comes round again. Below is the basic method to stack your firewood to maximize the drying process.
Ideally you want to position your firewood stack in Zone 1. In the winter, depending on how many appliances you use the wood for, you will need to visit the stack one or more times a day, so it makes sense to have it near the house. Insects and rodents, however, will probably inhabit the stack, so you do not want it directly adjacent to the house, to avoid these critters making their way into your home. Place on well-drained ground, in a sunny position that is well ventilated. Avoid too much shade, as this will prolong the drying process. However, if you live in an area that gets a lot of rainfall you will probably want to cover the pile for protection, so if you add a tarp or metal covering, make sure you leave the sides of the stack exposed for ventilation.
To aid air circulation around the whole stack, and to prevent the wood absorbing moisture from the ground, it is a good idea to elevate the stack. This can be as simple as using a few old wooden packing pallets – although these will need replacing after a few years, as they will rot – or constructing a dedicated platform from recycled timber. Another option is to simply place a couple of two-by-four planks on the ground before starting your firewood stack, but these will need to be treated to prevent moisture absorption.
The basic firewood stack is in a rectangular stack one log-length in width. This method requires sturdy vertical ends to contain the stack. The easiest way to create strong ends is to crisscross alternate layers of wood at right angles. This creates a stable anchor for your stack that contains large holes to allow air in. Build the first vertical stack where you want your firewood pile to start, proceed with stacking your wood, and then build the end stack to secure the pile.
Cut the Logs
The best shape to cut logs so that they both stack well and get the maximum ventilation is a wedge. You are looking for around a 90-degree angle, although for your appliances you may favor a sharper angle – just make sure you cut all the logs to the same angle for ease of stacking. Also make all the logs the same length. When cutting logs, try to chop with the grain for easier separation.
Place the lowest layer of logs bark side down if possible, as bark is natural moisture repellant. Stack the logs reasonably irregularly. You want gaps and spaces in the pile to allow airflow, which will dry the logs. Do not ‘recreate’ the round logs you cut by placing four wedges together. Place the top layer bark-side up. Check the pile regularly as you go to make sure it is vertically straight. Tap the ends of logs to into position as you go – this is a lot easier than trying to realign a stack that has reached waist-height or above.
If you are stacking your firewood against a wall, leave a gap between the wood and the wall to allow air to circulate. It is also a good idea to angle the stack slightly in towards the wall as you build it up, so that if shifting does occur the wood will fall towards the wall and remain upright. If the wall does not have an eave, stack the top layer of wood so that it extends beyond the layers underneath. That way, even if you don’t have any other covering, any rain will run off the stack. You could also, if you have any, place boards at an angle against the wall to protect the stack from the rain.
There is no exact science to determine when your firewood has reached the 20 percent moisture level that means it is suitable for use in your home appliances. However, there are certain signs that give a good indication. Dry – or ‘seasoned’ – wood will turn more grey in colour than unseasoned wood, and if you knock two pieces together they will have a higher pitched, more resonant sound than wetter pieces, which emit a low thud. The best clue, however, is that dried wood will show hairline cracks along its edges.