Lets Talk Energy Conservation!
Got Attic mould or Other Loft Problems?
It often happens to countless homeowners around the end of the year - you make the annual visit to your attic to collect the holiday decorations and what do you find? Spots and blotches covering the bottom of the roof sheathing. Worse yet - it turns out to be attic mould!
But just what does energy conservation have to do with mould in the attic? Well if you take a step back and consider how the house behaves as system, they are often directly related.
Building science experts have long been using the "house as a system" approach to diagnose the cause and origin of building defects.
For example, ice dams. These are often caused by warm air seeping into the attic which causes the snow and ice on the roof to melt. The water drains to the edge of the roof (which is colder than the rest of the roof because it is an overhang and not warmed by the attic), freezes and creates an ice dam. As this process is repeated daily, the ice dam grows larger. Eventually water is forced under a shingle where it can seep into the house.
Understanding how the house behaves as a system and the various causes and effects is necessary to diagnose most building related problems.
But how about that attic mould? How did it get there?
Mould requires chronic moisture to form and to thrive, so source(s) of moisture must be present. Possibly the moisture came from outdoors. The roof is newer and a quick check of the roof shows no obvious damage or leaks.
It is possible that the moisture came from indoors. During the heating season, the interior of the house frequently has high moisture levels, especially bathrooms and kitchens. A quick and easy check is to see if all bathroom fans, kitchen vents, etc. are properly ducted completely outdoors and not into the attic. Also check that the amount of insulation looks good and the attic is well ventilated.
But please don't give up - you are almost there! Just remember that your house as a system? You know that warm, moist air is in the house, but how is it getting into the attic?
By air leaks! Air leaks are the leading source of energy loss in most houses, and a frequent source of chronic moisture that can cause attic mould. Most homeowners are well aware of air leaks around windows and doors (especially old ones), but many overlook the numerous gaps leading directly into the attic!
Have a look around the attic and you may find large gaps around recessed lights and fans, holes where wires or pipes are installed, even large gaps around the chimney. And don't overlook the whole house fan and especially the folding attic stair - a big, uninsulated hole in your ceiling that is often overlooked!
These uninsulated gaps can add up to a reasonably large holes that allows warm, moist air from the house to flow right into the cold attic. The warm moist air condenses on the cold roof sheathing, creating chronically damp conditions that can lead to attic mould growth. And the energy loss - it can be like leaving a window open all winter long!
Seal these air leaks and you stop a significant moisture source. And just think of all the energy you can save and the cold drafts you can stop!
About The Author
Mark D. Tyrol is a Professional Engineer specializing in cause and origin of construction defects. He developed several residential energy conservation products including an attic stair cover and a fireplace draftstopper. To learn more visit www.batticdoor.com.
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"most helpful information. checked the loft insulation (found to be ok) but did find the insulation was covering the vents, preventing the correct airflow. "
"OK, all very interesting but now I know how the mould is created, how do I treat it and/or \'seal the air way\' ???"