They were very vulnerable to attacks using fire and the wood would eventually start to rot. Due to these disadvantages, King William ordered that castles should be built in stone. Many of the original timber castles were replaced with stone castles.

In 1066, during the initial Norman Conquest of England, the vast majority of castles were made of timber and earth. These were known as Motte and Bailey castles. The "motte" was a large man-made mound of earth, while the "bailey" was a fenced-in courtyard at the base. The primary defensive structures—the keep (tower) and the surrounding palisade walls—were constructed from wood because it was readily available and allowed the Normans to build hundreds of fortifications very quickly to secure conquered territory. While stone was used for a few prestigious projects, like the initial stages of the White Tower (Tower of London), it was prohibitively expensive and slow to build. These wooden castles were highly effective for temporary defense but were vulnerable to fire and rot. As the Norman hold on England solidified in the decades following 1066, many of these timber structures were eventually rebuilt or "rendered" in limestone or sandstone for permanent durability and status.