A typical straight-wall structure is dangerous because its components can be ripped off even in a mild storm. The wind enters through the smallest crack, demolishing the entire building as if a bomb had detonated within. During a storm, changing wind speeds can put pressure on different portions of a building. If it fails, it can cause serious injury or death. The most severe damage from a tornado occurs at buildings with poorly constructed foundations or those that are built close to the ground. These structures are most common in areas where developers don't need to pay taxes on property they sell, so they build them quickly without regard for weather conditions. Even if a foundation is properly prepared, it can fail under the stress of a tornado if the house is not designed to withstand such force. A small building with no basement walls will likely collapse during a tornado. Large buildings with many glass windows and doors are also prone to failure. During a tornado, glass breaks into sharp shards that can cut you like knives. The metal frames of windows and doors can also twist off their hinges or pull away from their moorings, causing further injury and destruction. Finally, buildings with plastic siding or thin wooden roofs are at risk for collapsing roofing material. The wind can blow these materials off the roof and into people's homes.