Leonardo Da Vinci Castle

Not only were stone castles expensive to build in the first place, but their maintenance was a constant drain. They contained a lot of timber, which was often unseasoned and as a result needed careful upkeep. For example, it is documented that in the late 12th century repairs at castles such as Exeter and Gloucester cost between £20 and £50 annually.
Medieval machines and inventions, such as the treadwheel crane, became indispensable during construction, and techniques of building wooden scaffolding were improved upon from Antiquity. Finding stone for shell keeps and castle walls was the first concern of medieval builders, and a prominent concern was to have quarries close at hand. There are examples of some castles where stone was quarried on site, such as Chinon, Château de Coucy and Château Gaillard.
Brick-built structures were not necessarily weaker than their stone-built counterparts. In England, brick production proliferated along the south-east coast due to an influx of Flemish weavers and a reduction in the amount of available stone, leading to a demand for an alternative building material. Brick castles are less common than stone or earth and timber constructions, and often it was chosen for its aesthetic appeal or because it was in fashion, encouraged by the brick architecture of the Low Countries. For example, when Tattershall Castle was built between 1430 and 1450, there was plenty of stone available nearby, but the owner, Lord Cromwell, chose to use brick. About 700,000 bricks were used to build the castle, which has been described as "the finest piece of medieval brick-work in England". Many countries had both timber and stone castles, however Denmark had few quarries, and as a result, most of its castles are earth and timber affairs, or later on built from brick. Also, most Spanish castles were built from stone, whereas castles in Eastern Europe were usually of timber construction.