Looking ahead to summer with its long warm days, firewood is on our minds.
Whilst summer doesn’t seem the right time to be thinking wintery thoughts, you need to plan ahead.
Once dry, the energy contained inlogs by weight is much the same, as demonstrated by the graph below taken from a Forestry Commission publication, so by weight, hardwood and softwood are on a par with each other. This doesn’t mean they are equal though.
The hardwood is far denser and will release its energy slowly, this also means that you have less volume than the equivalent weight of softwood. So softwood gives you more logs for the same weight that release their energy quickly. As with so many things, a balance is the best thing. Softwood helps get a fire up to temperature whilst hardwood can then hold it there.
A key word in the above diagram is ‘dry’, oven dry may be taking it a bit far in terms of efficiency of production. Also, unless you keep the wood in similar conditions, it will reabsorb the moisture. How long to dry wood? This varies between species and we find that a lot of wet timbers (Lawson cypress, alder, willow) give up their moisture quite readily when exposed and that denser, drier feeling timbers (oak, sweet chestnut) need a bit longer to dry out. I think it is best summed up by Celia Congreve in ‘The Firewood Poem’.
The Firewood Poem
Beechwood fires are bright and clear
If the logs are kept a year,
Chestnut’s only good they say,
If for logs ’tis laid away.
Make a fire of Elder tree,
Death within your house will be;
But ash new or ash old,
Is fit for a queen with crown of gold
Birch and fir logs burn too fast
Blaze up bright and do not last,
it is by the Irish said
Hawthorn bakes the sweetest bread.
Elm wood burns like churchyard mould,
E’en the very flames are cold
But ash green or ash brown
Is fit for a queen with golden crown
Poplar gives a bitter smoke,
Fills your eyes and makes you choke,
Apple wood will scent your room
Pear wood smells like flowers in bloom
Oaken logs, if dry and old
keep away the winter’s cold
But ash wet or ash dry
a king shall warm his slippers by.
Keeping firewood stored somewhere dry with good airflow then is essential to keep the wood at its driest so that the most efficient burn can be had from it.
The wood piles also provide habitat for insects including bees, nesting places for birds, as well as sunny piles being popular with reptiles. We have quite often found lizards in stacks, or recently this slow worm in the stack of one of our customers.
Seasoned and dry is the key thing, which is why we have spent spring filling our log sheds for next winter with timber that has laid to dry for a year or more before being split open to further dry in sunny vented sheds for the winter ahead.
Tim – Woodland Ranger