"I've had 20 calls the last two days," says construction contractor Randy Zoller of Home Lumber Co. in Du Quoin about roofs leaking as melting ice backs water into a business or home with a flat or shallow roof.
"It's called capillary action," says Zoller, one of the most experienced roofing contractors on Southern Illinois.
By the time the "ice dams" and icicles have melted the damage has already been done and in some cases the problem corrects itself--until the next time it happens.
"The ice is slow to melt," says Zoller and the illusive roof leaks may linger for several days.
Public administrator Brad Myers said Tuesday, "We've got them here at city hall. There's one over at the chamber office. At least three churches and at least seven downtown business buildings are having similar melting ice and snow problems.
Ice dams cause millions of dollars a year in damage such as water-stained ceilings, rotted roof sheathing, deformed gutters, peeling paint, compromised insulation, mold infestation, and more.
You've seen it many times - a mass of heavy ice collecting at the eaves of a roof. But did you ever wonder why these hazardous (and dangerous) ice masses and icicles form? The answer is simple: Trapped heat in your attic melts the snow on your roof. The melting snow then trickles downward to the edges of the roof and re-freezes, over and over again, continually adding more ice mass, and eventually results in extreme havoc to the structure of your roof. You might not know the extent of the damage until it is way too late: Damage such as warping and detachment of eave troughs, fascia board warping, roof wood rot, and melting ice leaking into your house resulting in drywall and plaster stains. Why does this happen? You might be surprised by the answer. The power of ice is tremendous. When water freezes it expands and creates a huge force that pushes against anything in its way. This unstoppable force can bend steel like bubble gum. Imagine this huge level of pressure pushing against soft materials such as wood, aluminum, asphalt shingles, or bricks, concrete, and stone walls (all easy prey for ice dams). Clearly, the damage could be enormous.
What is the answer? Here it is: The only lasting solution to prevent roof ice damming is proper roof ventilation. Why? Because proper roof ventilation removes the trapped heat in your attic (the very heat that causes ice dams) and studies prove that a cool attic during winter stops the thaw/re-freeze cycle and thus stops the melting snow from re-freezing at the roof edges. But how does roof ventilation specifically prevent ice damming? The answer is to create an attic temperature that is close or the same to the temperature outside of the attic using specific roof/attic ventilation procedures such as soffit roof ventilation and ridge roof ventilation.
Proof of this heat loss theory is easy to see. Take a look at a house with many large icicles along the eaves, then, look at the detached garage roof with the same exposure to the sun. You will find that the unheated garage has little or no icicles.
After air sealing and insulating, be sure you have adequate passive roof ventilation. This may be achieved by introducing ample eave/soffit vents in conjunction with a continuous ridge vent. This allows for natural convective air movement across a large percentage of the roof deck. It will keep your attic cold in the winter, minimizing the premature snow melt that causes ice dams. In the summer, you will have a cooler attic. You will also have less chance of condensation and mold.
As a last measure of prevention, a waterproof membrane can be installed along the lower 36" edge of your roof. This underlayment is a peel and stick product that prevents leaks and ice dams.
Following these guidelines will not only solve the root causes of ice dams, but it will save you money in wasted energy (conditioned indoor air), and ensure that your home is durable for many years to come.
The downside: Most of this will have to wait until warmer weather.
Zoller said he expects a busy spring for his construction company because of the winter ice and snow damage.