Homeowners can handle limited cosmetic updates such as painting, installing hardware, or replacing a mirror. However, plumbing, waterproofing, and electrical work in Los Angeles must comply with Title 24 codes and typically require permits and inspections. Improperly installed shower pans or incorrect slope (less than 1/4 inch per foot) often lead to water pooling and long-term leaks. Faulty GFCI wiring in wet areas creates shock hazards. These mistakes frequently cost more to correct than hiring a licensed contractor from the start. DIY may reduce labor costs on surface-level tasks, but structural, plumbing, and electrical changes should involve licensed professionals. The risk of water intrusion, mold, and failed inspections outweighs short-term savings when complex systems are involved.