An important stage of designing in wood is to consider wood movement. 

But solid wood furniture is affected by heat and moisture. A hot dry environment will cause wood to shrink, whilst a damp environment will cause it to swell. 

Knots, cracks, drying shakes and movement are inherent characteristics of natural timber and are not considered a fault in the wood or workmanship. If furniture is exposed to extremes of temperature, such as next to a radiator or exposed to direct sunlight or by an unnaturally dry atmosphere, the wood will move.

To allow the wood to flex and shrink we use certain type of wood joints. The photo above shows solid oak door frames with mortise and tenons.