The Author is the owner of Battic Door Energy Conservation Products in Mansfield, Massachusetts. He specializes in the cause and origin of construction defects, and has developed several residential energy conservation products, including an attic stair cover and a fireplace draftstopper.
It 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 mold!
What does energy conservation have to do with mold 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 mold? How did it get there?
Mold 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. Possibly 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 check shows that all bathroom fans, kitchen vents, etc. are properly ducted completely outdoors and not into the attic. The amount of insulation looks good and the attic is well ventilated.
Don't give up - you are almost there! Remember the 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 mold. 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 gaps can add up to a large hole 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 mold 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!
Imagine leaving a window open all winter long - the heat loss, cold drafts and wasted energy! If your home has a folding attic stair, fireplace or clothes dryer, that may be just what is occurring in your home every day. These often overlooked sources of heat loss and air leakage can cause heat to pour out and the cold outside air to rush in - costing you higher heating bills.
Air leaks are the largest source of heating and cooling loss in the home. Air leaks occur through the small cracks around doors, windows, pipes, etc. Most homeowners are well aware of the benefits caulk and weatherstripping provide to minimize heat loss and cold drafts. But what can you do about the four largest ”holes” in your home - the folding attic stair, the whole house fan, the fireplace and the clothes dryer? Here are some tips and techniques that can easily, quickly and inexpensively seal and insulate these holes.
When attic stairs are installed, a large hole (approximately 10 square feet) is created in your ceiling. The ceiling and insulation that were there have to be removed, leaving only a thin, unsealed, sheet of plywood. Your attic space is ventilated directly to the outdoors. In the winter, the attic space can be very cold, and in the summer it can be very hot. And what is separating your conditioned house from your unconditioned attic? That thin sheet of plywood.
Often a gap can be observed around the perimeter of the door. Try this yourself: at night, turn on the attic light and shut the attic stairway door - do you see any light coming through? These are gaps add up to a large opening where your heated/cooled air leaks out 24 hours a day. This is like leaving a window open all year round.
An easy, low-cost solution to this problem is to add an attic stair cover. An attic stair cover provides an air seal, reducing the air leaks. Add the desired amount of insulation over the cover to restore the insulation removed from the ceiling.
Much like attic stairs above, when whole house fans are installed, a large hole (up to 16 square feet or larger) is created in your ceiling. The ceiling and insulation that were there have to be removed, leaving only leaky ceiling shutter between the house and the outdoors.
An easy, low-cost solution to this problem is to add a whole house fan cover. Installed from the attic side, the whole house fan cover is invisible. Cover the fan to reduce heating and air-conditioning loss, remove it when use of the fan is desired. If attic access is inconvenient, a ceiling shutter cover is another option for reducing heat loss through the ceiling shutter. Made from R-8, textured, thin, white flexible insulation, and installed from the house side over the ceiling shutter with Velcro, a whole house fan shutter cover is easily installed and removed.
Sixty-five percent, or approximately 100 million homes in North America are constructed with wood or gas burning fireplaces. Unfortunately there are negative side effects that the fireplace brings to a home especially during the winter home-heating season. Fireplaces are energy losers.
Researchers have studied this to determine the amount of heat loss through an unlit fireplace, and the results are amazing. One recent research study showed that an open damper on an unlit fireplace in a well-insulated house can raise overall heating-energy consumption by 30 percent. This is truly a remarkable statistic!
A recent study showed that for many consumers, their heating bills may be more than $500 higher per winter due to the air leakage and wasted energy caused by fireplaces.
Why does a home with a fireplace have higher heating bills? It is simple - hot air rises. Your heated air leaks out any exit it can find, and when your heated air is drawn out of your home, cold outside air is drawn in to make up for it. The fireplace is like a giant straw sucking the heated air from your house! An easy, low-cost solution to this problem is to install a fireplace draftstopper, an inflatable pillow that is installed into the fireplace below the damper. As the pillow is inflated, it seals the damper, eliminating any air leaks and heat loss. Other benefits include the reduction of downdrafts, toxins, odors, pollutants, and noise. The pillow is removed whenever the fireplace is used, then reinserted after. Completely reusable and available in two sizes to fit any masonry or zero-clearance fireplace, the draftstopper can pay for itself in less than a month!
In many homes, the room with the clothes dryer is the coldest room in the house. Your clothes dryer is connected to an exhaust duct that is open to the outdoors. In the winter, cold air leaks in through the duct, through your dryer and into your house.
Dryer vents use a sheet-metal flapper to try to reduce this air leakage. This is very primitive technology that does not provide a positive seal to stop the air leakage. Compounding the problem is that over time, lint clogs the flapper valve causing it to stay open, or a cold breeze can blow the flapper open, allowing frigid air right to come right into the house.
An easy, low-cost solution to this problem is to add a dryer vent seal. This low-cost, easily installed vent is mounted on the outside of your house, and reduces unwanted air infiltration, and keeps out pests, bees and rodents as well. The vent will remain closed unless the dryer is in use. When the dryer is in use, a floating shuttle rises to allow warm air, lint and moisture to escape. If your home has a folding attic stair, a whole house fan, a fireplace, and/or a clothes dryer, you can easily, quickly and inexpensively seal and insulate these holes.
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