Firewood quality is now more important than ever as more and more people install wood burning stoves and the message about quality spreads. But what is, best quality firewood and how do you get the best firewood burn quality.
Quite simply it’s all about moisture content. The drier the wood the better it burns. Freshly cut wood will contain about 60-70% moisture content depending on species but to achieve the best firewood burn quality, the wood must be dried to below 25% moisture content, but it’s almost a case of the drier the better. This ensures a clean burn with maximum heat output.
It takes a long time to season wood naturally – up to three years. Be careful when buying your logs and make sure you get a full understanding of the quality you are buying. Many suppliers will claim the wood has been ‘down’ for two years and therefore dry. That does not mean it’s dry. It is not about the time the tree has been cut down, but more about how the wood is stored. It must be sawn into log size, split and stored under cover for meaningful seasoning to take place. The best thing to do is check the moisture on delivery with a moisture meter.
Hardwood Firewood versus Softwood Firewood
Many people say you should not burn softwood as it smokes, tends to spit, burns too quickly and can tar up the chimney. Once again if you buy kiln dried logs or have the best way to season firewood in a dry and airy store and can dry to a moisture content below 25%, then you will not have any of the above problems. These only arise when the wood is not sufficiently dry.
Softwood (Spruce, Pine, Larch, Douglas Fir etc) will have the same energy content per kilogram as hardwoods (Oak, Ash, Beech, Alder, Birch etc), however being far less dense, you will need up to twice as many logs (or volume) to achieve the same heat output.
We only use British hardwood logs as we presently regard them as providing the best value for money.
Firewood Quality Chart
The following firewood chart shows the typical species that we use for our British hardwood firewood, although we have added at the end a photo of Softwood Pine just to show the difference visually. The aim of this poster is to help you identify the most common types of firewood that you may have had delivered. It will help you to better understand different species and the different way they each burn. Although all hardwoods, they will burn with slightly different characteristics.
- Oak Firewood
- Is very dense and takes a long time to dry to the core, but makes a great firewood with a long burn and good heat output. At times, this wood will require a little more draft/air from the stove setting to maintain a good burn, however once a good base is established, then the burn time will be very long.
- Ash Firewood
- Many people say this is the ‘king of firewoods’ and claim it can be burnt wet. Yes, it can dry quite quickly but still don’t burn it green. The fundamentals of firewood burn quality still apply and the moisture content must be below 25%. Ash wood gives a nice bright flame and burns very nicely albeit slightly faster than oak
- Beech Firewood
- Like oak, this is a very dense species and needs a lot of drying, but once dry burns with a nice bright yellow flame and for a long time. It also has a smooth bark so nice to handle.
- Alder Firewood
- Can be quite a dense wood and characteristically has quite a distinctive orangey flesh colour. Once dry it can actually be quite light in weight and will therefore burn quite quickly. Alder is more commonly from Eastern Europe. It is highly unlikely for you to be able to buy 100% alder sourced from the UK.
- Birch Firewood
- One of the most attractive of logs due to its silvery, flakey bark. Burns with a nice bright flame, but will burn quite quickly. As with Alder any supply of 100% Birch will almost certainly be from Eastern Europe and not British.
It is essential that you use dry firewood in your stove. Stove manufacturers only recommend a maximum of 20% moisture content and so you need to look for the new HETAS/Woodsure, ‘Ready to Burn’ logo which guarantees the logs are below 20%. This scheme is supported by DEFRA to help improve fuel quality. All Certainly Wood kiln dried logs are approved under this scheme.
This quality will ensure a clean burn with no blackening of the stove glass or build-up of soot or tar in the chimney or flue. It also means that in an efficient stove, you will actually use far less firewood, so more cost effective.
Our kiln dried logs are ‘Ready to Burn’ so you need to ensure they are stored in a cool dry place, either in a log store or garage.
These appliances are becoming more and more popular whether just for home cooking or within restaurants and pubs. The same principles apply as for the wood burning stove, the wood must be dried to below 20% moisture content so look for the ‘Ready to Burn’ logo for guaranteed firewood quality.
These appliances generally benefit from a smaller diameter log, as chefs require a good flame as well as quick heat. We have the perfect selection of British kiln dried logs for cooking over. Ring us for more details about the supply of kiln dried cooking logs to homes, restaurants, pubs and hotels.
When burning firewood logs on an open appliance, it’s impossible to control the air flow. Because of this, very dry firewood can sometimes burn too quickly but you still want to get good heat output and avoid sooting up chimneys etc.
The best solution for this is to burn our ‘kiln dried chunky logs’ that have a thicker diameter (10-21cm) and so provide a longer burn. The moisture content in the centre of the log is naturally a bit higher. (Av 30%). However, it is also just as important to have some smaller logs for getting the fire started, so perhaps consider a combination of standard and chunky logs, although we cannot mix these in single packs.
Never be tempted to go for poorly seasoned firewood – Yes, they will burn slower, but you won’t get the heat output and you will actually end up using up to twice as much firewood to generate the same heat AND you will get the soot and tar build up in your chimney and ultimately you could be heading towards a chimney fire!
Outdoor burning is just as important and in some ways, dry wood is even more critical. Whether the appliance is just for sitting around on a summers evening or perhaps cooking over, two things are vital - good heat output and minimal smoke. The latter is inevitable when using wet wood, but get a good fire going with dry wood and there will be barely any smoke.
So, once again we recommend only using ‘Ready to Burn’ kiln dried logs, although a combination of products will work even better and provide flexibility through burning.
We have Flaming Firewood product sold in small bags. These are still kiln dried, but offer a range of shapes and sizes within each bag and are perfect for these applications to get the fire going and we highly recommend you start your fire at least an hour before you need it. Once going, you can add larger logs for a longer burn, but only once you have a good base to the fire. Chunky logs can be used in this instance or our longer 35cm kiln dried logs. Log size will depend on your appliance size.
Nearly all our logs are cut to a length of 25cm (+/- 10%) and after consulting with the majority of UK stove manufacturers we know these will fit 99.9% of UK stoves.
The diameter of our standard logs is 5-15cm measured at the widest point of the log. This provides smaller logs to build a good base to the fire and larger ones for a longer burn.
We also provide logs with a length of 35cm and 50cm for larger fires or stoves. As they are longer logs, they are also slightly bigger diameter than the 25cm logs.
When buying in bulk, you can purchase a large or small bulk bag of loose logs or, for the convenience of movement, little bags on a pallet of 50 or 80. Of all the products, the large bulk bag is the most cost effective.
Bulk bags are ‘loose-filled’ i.e. dropped into the bag from a conveyor. The logs are therefore not stacked in the bag. We know that the volume is correct as we check the volume in a metal cage measuring 1m x 1m x 1.2m or 1.6m tall. Fill these to the top and we confirm the volume is correct.
The little bags have the logs packed by hand so actually, they are termed as ‘stacked’ volume and each bag contains 0.02m3. I know that makes it confusing, but it’s a HETAS requirement to declare volumes. However to simplify things the following table converts everything into a ‘loose-fill’ equivalent.
Firstly, the 1.2m3 bulk bag holds approx. 36 small bags and the 1.6m3 48 small bags, so the bulk packs convert as follows:
We understand buying kiln dried logs in bulk is a big commitment, that's why we offer our Certainly Wood Starter kit everything you need for the perfect fire, giving you the opportunity to try our products before buying large quantities. Our starter kit contains, 100% quality assured British kiln dried firewood, kiln dried kindling and Flamers natural firelighters - plus a handy box of matches. Our starter kits cost £10 per box with FREE delivery.
However, the really best way to check the moisture content is by using a moisture meter. This will give you a pretty good guide as the actual reading of the firewood, both inside and out. Check inside by splitting a log open. Just be aware however that moisture meters are not always 100% accurate, particularly the very cheap ones.