The most common construction defects in California are foundation related, water-related, and roofing related defects. Foundation related defects usually involve cracks in the foundation and building slabs, unevenness in-floor slab, etc. These cracks are frequently caused by unstable soil in reaction to earth movement. Water-related defects include water intrusions, improperly installed plumbing systems, improper drainage systems, etc. Roofing related defects include roof leaks, inadequate ventilation, weathered flashing, etc. Other common types of defects include buckled sliding, over-stressed structural members, difficulty in opening doors and windows, etc.