It is common for homes and buildings that are constructed during rain or snow to have problems with mold during warmer temperatures and humidity. Other situations that lead to mold growth include condensation from running hot water without venting the steam outside, leaky plumbing, roofs and clogged gutters, moisture intrusion from water damage, or flooding, and when indoor air is warmer than outdoor air, moisture collects on cold windows, walls, pipes and roofs. HVAC systems are notorious for spreading mold throughout the ventilation if filters are not routinely changed. Mold grows well on paper products, cardboard, ceiling tiles, and wood products. It can also grow in dust, paints, wallpaper, insulation, drywall, carpet, fabric, and upholstery.