Mold in the Basement
Causes of Mold in the Basement
The basement is one of the rooms in the home where mold most often grows. The main reason why mold so often grows in the basement is because of the many moisture sources to be found in the basement.
Because the basement gets very little ventilation, damp areas in the basement take a long time to dry out and humidity often remains high. A lack of sunlight also has the same effect of not helping the basement dry out quickly. These factors make it very hard to keep a basement dry.
On top of this the basement is one of the most seldomly frequented rooms of the house meaning mold can often grow without anyone noticing for long periods. The basement is also one of the most neglected rooms during cleaning and so it can be a long time before any mold growth is cleaned up and there usually is a lot of dust and debris around which mold can grow from.
Building materials in the basement such as drywall, wood and insulation also provide abundant food sources for mold to grow on.
Condensation Causes Mold in the Basement
One of the main sources of moisture in the basement is condensation. Because the basement is the lowest room in the house it is usually colder than other rooms and this leads to an increased amount of condensation.
Condensation collects on cold metal pipes as well as on cold concrete floors in the basement, even if there is carpet over the top, and on walls. Areas like this where condensation frequently occurs are good spots to look for mold growth.
Flooding and Basement Mold
Flooding is another big cause of mold problems in the basement. Because of its low altitude the basement is the room where water will remain the longest after a flood.
Floods also create the opportunity for species of toxic molds to grow, such as Stachybotrys chartarum, which require materials to be very wet for many days before they can start to grow.
Mold from Leaks in the Basement
Water leaking into the basement is another frequent cause of mold growth. Leaking pipes inside the basement can create a build up of moisture leading to the beginning of mold colonies. Even the water from leaks in other rooms will often find its way down into the basement and create problems.
Cracks in basement walls may let water seep in from the ground outside the basement, especially if water builds up in the surrounding yard. Blocked gutters can also create a build up of water which in turn may leak into the basement through the walls or ceiling.
Basement Humidity and Mold
Not only can the above water sources facilitate mold growth but mold can also feed off humidity which is typically high in the basement.
When the moisture from the aforementioned water sources evaporates into the air it raises the humidity of the basement and the poor ventilation common in most basements ensures the humidity level remains high for a long time to come.
Besides supporting mold, a high humidity level also means standing water and damp surfaces take longer to dry out.
Signs of Mold in the Basement
The two main ways of knowing you have mold in the basement are by finding visible mold growth or by smelling the odor of mold in the basement. Because of the low air circulation in the basement, any mold growth usually creates a strong odor build up leading to a noticeable moldy smell in the basement. If you notice a musty moldy smell coming from your basement then it's likely you have mold growing somewhere in the basement.
Another clue that you might have mold in your basement can be if you or a family member starts to suffer the symptoms of a mold allergy. If the allergic reactions get worse when you're in the basement then you should inspect your basement for mold.
When looking for signs of basement mold it's also helpful to check the humidity in the basement. A humidity level greater than 55% can facilitate mold growth. However even if the humidity level is low it does not mean mold cannot grow if the mold has another source of moisture such as a water leak.
Finding Mold in the Basement
When looking for mold in the basement you should begin by trying to find any signs of moisture. Areas where there are signs of water damage or leaks are prime spots for finding mold growth.
Mold can grow on any objects or building materials made from organic substances. In the basement these surfaces can be found everywhere such as drywall, wooden building frames, carpet, insulation, wallpaper, furniture or cardboard boxes.
If you cannot find mold in your basement but you suspect it is growing somewhere don't forget that you always have the option of mold testing. Mold testing can be performed by professionals for you or you can do it yourself using mold test kits. Both air and surfaces can be sampled for mold spores during mold testing.
Mold Growing on Walls in the Basement
When searching for mold you should check around the perimeter of the basement by looking for mold on the walls. Mold often begins to grow low down on the walls and also in the corners more commonly.
Pay attention to walls near spots where there could be water leaks such as near pipes or walls under rooms such as the bathroom. Telltale signs that there could be a water problem with a wall include decaying wood, warped walls, peeling wallpaper and cracked or peeling paint. Furniture touching walls or close to them can often create mold growth there. Also feel if any of the walls are damp. Signs such as these that would be noticed in other rooms often go unspotted since the basement is so often neglected.
The wooden frames of the walls or ceiling in the basement should also be checked for mold growth. Mold growing on the wooden frames can spread through the wood and into other rooms of the house. Moldy wood will also be weakened as it decays while the mold eats it. The drywall that walls in many basements are made of are also a favourite food source for mold to grow on.
If you can't find mold growing on walls during a visual inspection it could be because the mold is growing under the wallpaper or on the other side of the wall inside the wall cavity.
Mold on Basement Ceiling
Mold grows on ceiling basements and it especially loves drywall ceilings. The most common places mold can be found on the ceiling are where water flows above such as the ceiling area under bathrooms, under the hot water system or under potential leaks. If you've had a leak in the house then make sure to check the area directly below it in the basement. If part of the ceiling is under the edge of the house roof, mold can often grow in that area of the ceiling because of the buildup of water above caused by run off from the roof. If you can't find mold on the underside of the ceiling be aware that it could be growing on the other side in the ceiling cavity.
Mold in Insulation in the Basement
Any exposed insulation in the basement should be checked thoroughly for mold, especially if there was once a water problem in the basement or there was previously mold growth anywhere in the basement. Even if the insulation looks clean at first glance it can be a reservoir for mold so it should be properly checked. If you do find any mold in the insulation then that insulation will have to be removed and replaced as the mold won't be able to completely cleaned from it.
Mold on Basement Floor
The floor in the basement can easily grow mold, especially if you have carpetted floor. Besides mold growing well in carpet, the carpet can also hold a large amount of mold spores and other allergens. Examine the carpet and flooring carefully for any mold. Check if the carpet is damp which would indicate a moisture problem. If any mold is growing in the carpet then it should be removed and disposed. Remember to check below the stairs in the basement. Mold often grows on the floor beneath stairs and on the underside of the stairs themselves.
Mold Growing on Boxes and Furniture in the Basement
The basement is often used as a storage area. But if mold begins to grow in the basement you can be certain mold will end up growing on many of the belongings stored there such as cardboard boxes and clothes.
Objects made of wood such as furniture or other organic material are another thing that mold soon ends up growing on if there's a moisture problem. Upholstered furniture especially soaks up moisture and is a prime candidate for mold growth. Furniture should also not be kept close to or touching walls as this frequently leads to mold growth around that area because of condensation and diminished air flow. When checking furniture for mold remember to check underneath and to look inside if checking cupboards, drawers, etc.
Mold in the Basement from Pipes
Leaking pipes in the basement, or above the basement, have the potential to cause mold growth. Pipes also create moisture problems through condensation which forms on the metal due to the cold air of the basement.
Mold in Basement Ducts
Unseen mold could also be lurking in vents, ducts or air conditioning and heating systems that lead into the basement so don't forget to check inside these areas.
Prevent Basement Mold
To prevent mold beginning to grow or returning to the basement you need to minimize basement moisture. Find and fix any sources of moisture in the basement such as leaking pipes, condensation or leaking roof. Be on the lookout for water build up in the future to prevent basement mold.
To fix moisture seeping in through the walls or floor from the ground outside you can have your basement professionally waterproofed. Otherwise apply sealant to floor or wall areas to stop water getting in. Any cracks should be filled up using a water proof filler.
Reducing Humidity to Prevent Basement Mold
Keep the humidity level in the basement below 55% to ensure mold cannot grow from the moisture in the air. Use a dehumidifer if necessary to keep the humidity below this level. Ventilation will also help reduce humidity. If your clothes dryer is in the basement make sure to vent the air from it outside as drying wet clothes in the dryer evaporates water into the air which greatly increases humidity. Maintaining a low level of humidity in the basement will also cause any damp surfaces to dry out quicker.
Regularly Cleaning the Basement
Don't neglect your basement when it comes to cleaning the house. Vacuuming the basement with a HEPA vacuum and cleaning it once a week will effectively help to prevent mold.
Landscaping
Water build up in the yard and ground around the basement can cause frequent water problems for the basement. If the ground around your home slopes towards your house rainwater will end up building up at the foundation and basement. If this causes constant problems you might even need to do some landscaping to modify the slope of the ground around your home so water drains away from the house. Alternatively ditches and drains can be dug to channel water away from the home.
Basement Mold Removal and Remediation
Ideally you should hire a professional mold service to remove mold growing in the basement, especially if the area of mold growth is large.
For more information on how to perform mold removal and remediation in the home visit: