What moisture content should Ash and Beech firewood have?

Ash and Beech firewood should have a moisture content of no more than 20% when it is burned. Below this level, the logs can ignite more readily, burn at a higher temperature and produce substantially less smoke than wet or insufficiently seasoned wood.

In England, firewood sold in quantities of less than two cubic metres must be certified as Ready to Burn. That certification confirms that the wood has a moisture content of 20% or less. The rules apply to individual bags and smaller loose deliveries, although different requirements apply to deliveries of two cubic metres or more. Government guidance on selling domestic firewood explains the requirements in detail. 

Moisture matters because some of the fire’s energy must be used to evaporate any water remaining inside the log. The wetter the wood, the more energy is wasted before the wood can burn effectively. This results in less useful heat entering the room and can cause smoky flames, blackened stove glass and increased deposits within the chimney or flue.

Kiln drying accelerates the natural drying process in a controlled environment. It helps bring the internal moisture level down consistently, rather than merely drying the outer surface of the log. The result is firewood that is ready to use when it is delivered, provided it is subsequently stored correctly.

If you use a moisture meter, split a representative log and test the newly exposed centre. Testing only the outer surface can produce a misleading reading because the outside may be much drier than the middle. Take readings across the grain and check several different logs rather than relying on a single measurement.

Dry firewood can absorb moisture again if it is left exposed to rain or stored directly against damp ground. Keep Ash and Beech logs under cover, raised off the floor and surrounded by enough ventilation to prevent condensation. Avoid completely sealing the wood inside an unventilated plastic sheet.

Using firewood with a moisture content of 20% or less means easier lighting, more heat from each log and cleaner combustion. It is one of the most important factors in getting good performance from either Ash or Beech.