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Air sealing and insulation of the exterior top plates is critical to preventing that warm and moist air from warming the roof deck.
Attic ventilation is critical to keep that attic dry and as close to ambient air temperature.
Keep in mind that some ice dams are not preventable regardless of insulation and ventilation. That being said, I would venture a guess that 90% of ice dams are the result of poor insulation and ventilation.
We've encountered lots of ice damming in the the Chicago area. I agree with you, don't go on the roof now, it's too dangerous. Attic/roof ventilation and insulation are key factors in the creation of ice dams. If you're experiencing active leaking into your home now I'd consider using a snow rake w extension pole( while standing on the ground) to pull the snow off the leaking ice dam area. This might slow down the leaking by exposing the snow/ice melt area and decreasign the amount of snow melt contributing to the ice build up.
When spring comes, and it will! Consider installing a quality gutter/downspout snow/ice melt system in the problem areas. We've used the engineered systems made by WarmlyYour's http://www.warmlyyours.com/en-US/snow-melting/roof-deicing to solve ice dam problems for many of our clients. See the attached photo of a client's home in Wilmette, Illinois 60091 with a snow melt system actively working.
Once again- stay off the roof !
One easy fix for homeowners to prevent ice dams from the attic is to ensure proper airflow "intake" from the eaves. In many cases, the insulation is blown tight to the soffit which cuts off the ventilation at the intake. Installing Styrofoam baffles at the eaves between the joists to create the required 2" separation is fairly easy to do from the attic area. I normally would not recommend homeowners to take on this challenge unless they have experience working in the attic. Since the flooring in the attic area is not finished in most cases, the homeowner must be careful to only step on the joists when working or they will potentially fall through the ceiling / drywall. For this reason, it is recommended that a professional handle this type of install to avoid injury.
Eric Consuegra, Arocon Roofing & Construction
An ice and water shield is a key component of most roofing systems. Just what is ICE and water shield? It is a type of roof underlayment used in new construction and re-roofing projects. It is commonly used in leak-prone areas near eaves and in valleys. Also, it is frequently applied in problem areas like chimneys, skylights, dormers and vent pipes. Sometimes, for the ultimate in leak protection, this special membrane is installed across the entire roof.
A properly installed ice and water shield protects against the following:
Ice Dams - A Special Challenge
Recent severe winters made many Maryland property owners acutely aware of the problems posed by ice dams. Significant snow loads, combined with heat rising from living spaces, cause ice dams to form. Freezing and thawing cycles also add to the problem. Rising heat melts snow on the roof, but when the water reaches the edge of the roof, the heat source stops and the water freezes.
As this cycle repeats, ice dams can build up. Just as a lake forms behind a dam across a river, pools of water can gather behind ice dams. This standing water may migrate under roofing materials where it can cause dry rot, mold and/or mildew. The water may also migrate into the attic before staining and damaging ceilings and walls.
Installation of an effective ice and water shield is a proactive measure that can prevent expensive repairs and provide peace-of-mind.
Sometimes, severe winds in thunderstorms can create enough lift to allow heavy rain to work its way under shingles. From there, moisture can migrate down the roof until it reaches vulnerable areas. Also, heavy rain can increase flowing water to the point that it exploits vulnerable spots, especially those found in aging or improperly installed roofs.
The advantages of a high-quality ice and water shield are many:
In partial ice and water shield installations, existing roofing materials are removed along eaves, rake edges, valleys and other problem areas, right down to the roof deck. The self-adhering ice and water shield is then applied directly to the roof deck, and the shingles are then replaced in these areas. To ensure that one gets the full waterproofing potential out of such a product, expert installation by qualifiedroofers is important.
Leak Protection Under Metal and Shingle Roofs
Ice and water shields are a valuable addition under a wide variety of metal and shingle roofs. GAFoffers two kinds of ice and water shields - StormGuard and WeatherWatch.
StormGuard is a film-surfaced membrane that is appropriate for use under both metal and shingle roofs. It is a Good Housekeeping Seal recipient, and it is a component of the GAF Lifetime Roofing System.
WeatherWatch is a mineral-surfaced barrier that is appropriate for use under shingle roofs. It features a fiberglass-reinforced layer that resists buckling and wrinkling under shingle roofs, promoting a flatter roof. It's been awarded the Good Housekeeping Seal as well, and it is also a part of GAF's Lifetime Roofing System.
Hope this help!
The best way to fix and resolve ice dams is actualy proper isulation in the attic space. Next is proper ventilation. Both intake and exhaust. These are critcal but rarely done correct and very costly and hard to do rero.
If the above are not done then a good qulity ice melting system is best. Either a commecial grade heat cable/heat tape or an ice melting system such as a heat panel.
Never use a continous watage cable as they are not safe or effecient.
Only use a self regulating cable as they are safe and effecient.
You will want the cable in the gutters and downspouts first, the next step is cable in the valleys and lastly weaved on the roof.
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