2M Crate Kiln Dried Oak/Ash FirewoodKiln dried ash/oak firewood, 2.98 m3 loose, £95 / m3. Crate of Kiln dried ash & oak in similar proportions are excellent for heat, burning slowly and steadily and producing little ash, have much higher energy content per m3 and so release more heat per pallet. Kiln dried oak also produce long-lasting fires and coal beds. Oak is very dense hardwood tree, so it burns for a very long time. Getting it started is the tricky part for the oak, though. Because of its density, it requires continuous high heat to really start it burning well and once it does get burning, there isn’t much maintenance that must be done.