Why is black mold growing in my attic? 866 543-3257

Why is black mold growing in my attic?

Why is black mold growing in my attic?Why is black mold growing in my attic?  Is a question I have been hear alot lately.  Let’s look a bit more into the attic black mold problem and find out why it is growing in your attic. There are actually several different reasons for the attic mold to appear on the inside of the roof sheathing.  That is why an attic inspection (and attic black mold treatment) are such an important part of home maintenance, and should be performed before even putting your house on the market.

Why is attic black mold growing under my roof?

Many factors can cause attic black mold to grow on the inside of your roof sheathing, and unfortunately the only way to find it is to go look for it. Some attics have easy access and a floor so you can walk around, but some have terrible entrances and no floors and you have to walk on the rafters.  If you find it too hard to get into or look around your attic then I suggest calling a professional.  Spotting and fixing  a problem right away can mean the difference between a few hundred dollars and several thousand dollars.  Plus if you are planning to sell your house it is better that you find the problem and not the potential buyer’s inspector.  Below are the 10 main reasons responsible for black mold growing in your attic:

  • The number one cause of attic black mold growth is inadequate ventilation of the attic and a lack of vents that instead of circulating the air between outsider and inside, trap air which condensates on the inside of the roof sheeting during the winter.


  • Dryer / kitchen / bathroom vents blowing into the attic instead of outside are often responsible for condensation, frost and attic black mold growth.   These vents blow warm moist air, just what mold needs to grow into a dark area with ample food for mold (the wood of your roof).  This combination makes for perfect conditions for mold growth.  This is an easy thing to fix and before you buy a home or if you own a home you really should have checked out.


  • Inadequate or missing attic floor insulation.  Sounds innocent but think of your attic as the area under your roof and above your house.  If there isn’t enough insulation the heat and moisture are escaping to the outside.  A good layer of insulation on the floor of your attic will keep the heat in your home and not allow for condensation in your attic which causes all of the problems.


  • Poor / improper cathedral ceiling insulation may also be responsible for attic black mold contamination.  Cathedral ceilings are becoming more and more popular but insulating them is tricky.  If airflow is restricted between the ceiling and roof condensation will build up and mold will certainly grow.  I have also seen this condition in cape style homes where people have made a second floor out of the attic.


  • Furnaces and water heaters produce significant amount of heat and if installed in a poorly ventilated attic .  Some homes have the furnace and water heater in the attic.  It is an unusual setup but does occur.  If the system is not contained within a closet then the heat that they produce will make more condensation and more mold.


  • Plumbing vents open into the attic discharge moist sewer gases into the attic.  Crazy as this sounds I have seen it.  It also makes for a smell, a buildup of methane which can lead to an explosion.  If you have your sewer line ending in your attic, mold is the least of your problems.


  • Uninsulated forced air heating system ducts –they waste energy and increase chances for attic black mold.  This is something that I see all of the time.  It is no one’s fault because uninsulated ducting is all that the builders had in those days.  This can be an expensive fix because it requires removing the old ductwork and replacing it with insulated ducting.  The uninsulated ducts allow warm air or cold air in the summer to escape, moisture condenses on them and you have a puddle and puddles lead to mold.


  • Poorly insulated ceiling openings, attic access, kitchen openings need to be insulated so there is an air tight bond around them.  Small openings can let a lot of warm air escape and cause condensation and mold in the attic. Some homes have more than one attic and the upper one, which is usually located above the bedrooms and bathrooms is always more susceptible of being contaminated with black mold. Warm air from lower parts of the house will naturally rise up and find its way through improperly insulated sections and cause problems.


  • Leaking roof – This goes without saying but you would be shocked how many people don’t pay attention to a stain on the ceiling.  If water is leaking through to the living area you can bet the attic is wet and mold is growing.


Any warm air trapped under the roof will cause condensation to form allowing mold to grow.  Good ventilation is very important, and can keep your home healthy.

2016-11-14T13:12:25+00:00 August 20th, 2012|Blog|
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