Green oak is wet, with 80% of its weight being water. Over time, as it dries out, the wood fibres will shrink. This shrinkage causes cracks to develop in the middle of each face of a beam, opening at a rate similar to the shrinkage itself. In reality, larger beams will undergo little change in section size, while smaller beams—like those measuring 125mm or 5 inches—may experience shrinkage of up to 7% of the section size. Oak does not shrink measurably in length. Additionally, changes in temperature and humidity throughout the year have almost no impact on an oak frame.