Listed below are some of the common places in the home where you may find mold
and why you find it.


Leaky Roofs are the primary contributor to attic mold growth. Having a good knowledge of your roofs' depreciation will save you money in the long run. (The average roof lasts 12-16 years.) Many roofs are not proactively fixed and therefore cause significant damage as they deteriorate. Most roof leaks are discovered long after they begin allowing ample time for mold to colonize.

Exhaust Fans from bathrooms that vent directly into the attic, instead of outside, are very problematic. The climate of your attic is not typically controlled by the use of an HVAC system. Therefore, the attic air mass is typically very hot in the summer and will be a great place for mold to grow when the moisture from a bathroom vent is added. All All Bathroom exhaust fans should be directed outside.

Wet Insulation will remain wet for long periods of time while holding this moisture against organic building materials that can develop mold. Insulation itself is not a food source for mold, however, it does collect and retain debris, which will support mold growth. Wet insulation should be removed and replaced by a certified remediator.


Water follows the path of least resistance. Even though steps were taken during your home's construction to keep water out of your basement, eventually hydrostatic pressure will break down the walls and find places to infiltrate your basement. Usually, the first place your basement leaks is at the joint where the floor meets the walls (also known as the cove). This is because the wall and the floor were poured at different times and concrete will not chemically bond to another mass of concrete if it is already dry. Concrete is also porous and it will retain moisture. Often you will notice water staining on lower blocks that are holding water. Many times you will see this staining in the corners first, then moving towards the middle of the wall. In some cases you will see a white fluffy looking substance that is known as efflorescent, which is many times mistaken for mold. Efflorescent is actually the lime deposit left behind from moisture seeping through block wall. Although efflorescent is not mold, its presence indicates a moisture intrusion is present, which would warrant a mold inspection. Products like Dry-lock can prevent moisture from passing thru the block for a small periods of time but can eventually compromise the structural stability of your basement walls by allowing pressure to build up. Cracks or bows can both be signs of hydrostatic pressure against a basement wall.

Ceiling joists in humid or wet basements will grow mold. Often you will notice green or other colored molds on these beams. (It is important to note that you cannot determine the type of mold by color alone. Black mold is not always Stachybotrys sp. Only testing can determine spore types.) Mold will also appear on ceiling joists where plumbing pipes pass thru them. Condensation that builds up on the actual piping will saturate wood and in turn grow mold.

Insulation in basements (and anywhere else in the home) is susceptible to mold growth. The mold does not actually eat the non-organic insulation but the debris that lands or is caught in it. Insulation acts as a sponge when it is wet. It is very difficult to dry out. Therefore it is an excellent incubator for mold.

Block, concrete, and stone walls will all support mold growth if moisture is present. Look for water staining, efflorescent patterns, or general discolorations. Growth will also appear on floors where high humidity or standing water is present.

Dryer vents that are not properly vented are excellent starting points for mold infestations. The warm moist heat will condensate on almost anything it lands on making that substrate suitable for mold growth.

Other items of concern in a basement are cardboard boxes that lay directly on the cement floor. Cardboard is highly porous and will hold moisture for prolonged periods of time. Cardboard will also “wick” water, meaning water travels thru the cardboard to the contents inside. Leather, golf bags, fabrics, and furniture will also support mold growth in humid areas such as basements, attics, and crawlspaces.


Showers and tubs will leak if not properly sealed. (Shower and tub grout has a lifespan of 6 months to 2 years.) Many times these leaks go un-noticed until it is too late. Leaks in 2nd story bathrooms may become recognizable in ceiling drywall tape joints and discolorations of the floors below. You can clean mold that forms on the inside of a tub or shower with bleach because tubs and showers are made of non-porous materials and is easily wiped away. This mold is growing on debris that has landed on a synthetic surface and can be very easily remediated.

Mold can be found behind or at the base of toilets. In summer months toilet tanks will “sweat” and that moisture is easily transferred to the drywall directly under the toilet tank causing possible mold growth. Poor aim can also play a part in toilet area mold. You may consider using non organic and easily cleaned building materials around your toilet to avoid growth in this area.

Exhaust fans or lack there of can contribute to mold growth. Many bathrooms are not properly ventilated and moisture will condense on the walls and ceiling every time someone takes a shower or bath. Exhaust fans are used to prevent this but many are improperly discharged into the attic instead of outside. Discharging a bathroom fan to the attic will simply move the moisture problem to that space.

Pooling water that forms after someone leaves the shower will leak through poorly sealed floors and into ceiling cavities and sub floor area below, soaking building materials causing mold growth. You should take steps to ensure that excess water is cleaned up and not allowed to soak into the floor.




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