You always want the soil or the ground to slope away from your house. This will naturally lead water away from the foundation, and help keep your basement dry. Ultimately, the grade should slope 1″ per foot for 5′. If you don’t have a proper slope, it is possible that water will penetrate through the foundation, and your are likely to get mold problems in your house.
Missing downspout extensions
Make sure you have installed extensions on your downspouts, and keep them out at all times.
With no extension on your downspout, all rainwater that drains off your roof will end up at the foundation, and the chances to get moisture in your basement will increase. Moisture will increase chances for mold problems. The extensions should terminate a minimum of 5′-6′ away from the house.
Sump pump failure
The most common reason for a sump pump failure is electrical power outage. To safeguard yourself from this situation, it is recommended to install a back up sump pump system. It is recommended to check your sump pump for proper operation weekly. When a sump pump fails, it will cause moisture and humidity in your basement that again could lead to mold in the house.
Improperly installed sump pump hose
Make sure there are no leaks at the connection where the pipe penetrates through your wall. This is a typical area that can cause leaks by the foundation.
Do NOT install your sump pump hose parallel, close to the foundation. Most sump pump hoses will leak over time, and will cause leaks towards your foundation if not installed properly. Ongoing leaks close to the foundation could lead to basement mold.
Missing caulking around windows and exterior doors
Many windows and doors rely on caulking to keep water out of the house. As the caulking wears off over the years, these areas will become prone to leak. Recommend to monitor and replace caulking every 3-5 years. Often you can get mold problems from small leaks from your window.
Any naturally cold rooms, attics or other areas with exterior walls/roof and no heat source should be ventilated. When hot air leaks to the natural cold rooms or areas, condensation and moisture will appear. You will get a musty smell and likely get mold problems, especially with sheet rock, wood or other porous materials in the room. It is very important to have proper air movement to circulate the air, and keep the temperature below the dew point. An option to additional ventilation is to install insulation and proper vapor barrier in the room. Installed vent to a naturally cold room Microbial growth in attic as a result of improper ventilation.
Improper vapor barrier
Improperly installed vapor barrier will cause condensation in the wall cavities, and increase the chance of mold problems radically. The vapor barrier should be installed on the interior warm side of the wall, and NOT on the interior cold side of the wall. (This regards colder climates)
In every house there is warm air trying to escape through the building envelope. If the vapor barrier is correctly installed on the warm side of the wall, it will prevent warm air from entering the wall cavities, and no condensation will appear.
If the vapor barrier is incorrectly installed on the cold side of the wall, warm air will escape from your living areas to the wall cavities, and condensate when reaching the cold vapor barrier. This will cause moisture damage to the insulation, wood rot, and mold in the house.
Leaks from sinks and drain pipes
It is recommended to check your bathroom and kitchen sinks for leaks frequently. These places are often overseen by homeowners, and leaks could go on for weeks without knowing. Microbial growth are typically noticed growing on walls under counters.
Leaks through flashings, chimneys, or roof vents will cause moisture in the attic. It is recommended to go up to your attic annually and look for leaks or stains. Over time the wood will rot, and microbial growth will be likely, especially if sheet rock is present.
Reduce indoor humidity (to 40-50%) by venting bathrooms, dryers, kitchen fans, and other moisture-generating sources to the outside. Use air conditioners and de-humidifiers, increasing ventilation, and use fans whenever showering, cooking, dish-washing, and cleaning.