Mold growth is caused by Water Leaks or Elevated humidity in living spaces
Outside humidity in San Francisco is normally around 50%. In living and working spaces we find interior humidity to be between 40% and 52%. When the long term humidity exceeds 52% it becomes a concern. Humidity can be reduced by turning on the exhaust fans in the kitchen and bath, as well as opening the windows. Ventilation needs air coming and as well as air going out.
You can purchase an inexpensive humidity gauge from Amazon, Home Depot, etc. If you can measure it, you can control it. Everyone wins this way.
#1 - Water Leaks
If you see a leak try to stop it as soon as possible by turning of the water source, closing a window, or any other method appropriate. Then call your Property Manager or Landlord immediately. If it’s 4 am leave a message and follow up as soon as the office opens.
The sooner professional drying begins the less likely that mold growth will occur. Everyone wins this way.
The tenants are not displaced and have ruined contents; the landlord repairs the property much more quickly with less costs.
Tenants may also wish to consider renters insurance. Be sure water damage is a covered loss.
NOTE: Notify building management as soon as possible. It’s much easier and faster to clean up wet contents than wet, moldy contents. Some, or all contents may be lost to mold.
If you suspect this is brown or dirty water spill, block off the area immediately and notify building management. Do not try to clean up this type of spill. Do stop the water source, if possible. Leave the area. Wait for professional evaluation.
#2 No or Low Performing Exhaust Fans in the Kitchen and Baths
If moist air from your morning shower is exhausted immediately, mold is much less likely to grow in your bathroom and surrounding areas. To test the efficiency of your exhaust fans, turn the fan on. Then take one square of toilet paper and place it below the exhaust grate for the fan. If the paper sticks to the grate, the fan is working properly. If not, contact your property manager or landlord.
#3 No Insulation in Perimeter Walls
San Francisco is an old City and insulation wasn’t considered necessary in the past. So, in an older building if you place your bed or sofa immediately next to a perimeter wall, you will probably see discoloration (mold growth) on the wall and adjacent furniture. To avoid this, keep all furniture a minimum of 6″ away from perimeter walls. Mold will grow on wood, too. It is unrealistic to expect a landlord to tear down walls to insulated your apartment, so work together and keep your furniture 6″ away from perimeter walls.
#4 Too Many People Living in a Small Space
Rents in the City are high. I mitigate this situation, buy an expensive humidity meter and when the interior humidity reached 52 degrees, turn on the exhaust fans in the kitchen and bathrooms. Also, don’t overstuff closets. I know that’s a hard one, but you will be well served to rent a storage space for your extra contents rather than stuffing them in a closet.
Using communication among all occupants and management, you can have a healthy home for a long time!