Ice Damming - Roof Leaks

You have experienced, read, or heard about ice damming. You are familiar with the damage the phenomena can cause. Perhaps your Association has spent several hundred thousand or even over a million dollars on roofing improvements and/or replacements within the last few years. Why do we have leaks from ice damming? Wasn't the roof replacement performed correctly or designed correctly? The answer is simple, with a properly designed and installed roof system, the possibility of damage resulting from ice damming should be significantly reduced.

The four (4) main factors that cause ice dams are:

  • Snow / ice buildup on the roof.
  • Continuously warm/cold temperatures.
  • An under ventilated and poorly insulated attic (heat in attic).
  • Deficient roof installation (lack of ice and water shield, drip edge, insulation baffles. etc.)

A typical ice-damming event occurs when the heat escapes from the living quarters into the attic and eventually warms the roof deck. The combination of the sun and the interior heat combine to accelerate and exacerbate this process. The melting water runs down the roof deck until it hits the area over the eaves and the gutter. This area remains cold because it is not over a heated space and thus the water begins to freeze and the ice dam forms. As the ice dam builds, it begins to trap more snowmelt, extending the height of the dam. The melting water begins to pool and backs up under the shingles. Severe problems begin when no ice and water shield is present and no drip edge is located behind the gutters.

 

Many times the problem is partially attributed to the attic insulation being lodged tight up against the underside of the roof at the soffits, thus prohibiting the proper ventilation of the soffit vents. The lack of soffit baffles, to hold back the insulation and create an air space for the ventilation, greatly diminishes the performance of a balanced roof ventilation system. New roof installations and replacement projects should provide balanced natural draft roof ventilation. As stated previously, ice dams form when a roof has warm upper surfaces and cold lower surfaces. The solution is to equalize temperatures over the entire roof. Heating an entire roof is impractical (and extremely costly), so the most effective solution is to create a cold roof. The most efficient system uses an equal balance of ingress and egress ventilation. Cold outside air is drawn into the soffit vents where it continues up the underside of the roof decking and out through the ridge vent, dome (button) vents, or gable vents. This even distribution of airflow minimizes variations in roof temperatures from the peak to the eaves and reduces the possible occurrence of ice damming.

 

Another line of defense against infiltrating water is the proper installation of an ice and water shield or an equivalent waterproofing membrane and drip edge installation. The ice and water shield must project a minimum twenty-four (24”) inches past the interior face of the exterior wall to meet the building code requirements. The issue of proper ventilation and ice shields at the eave is not an option that the association may choose to comply with. They are code requirements. The issue of adequate ventilation is also a requirement of all shingle manufacturers to comply with warranty issues. If the association opts not to install adequate ventilation with a new roof, they are in effect voiding the warranty of the new shingles (typically a 20 to 30 year warranty).

 

An Association or developer can take additional steps at the time of construction or roof replacement that will greatly reduce possibilities of leaks resulting from ice damming. These include installing drip edges at the eaves and rakes and installing a continuous run of ice shield along the step walls, low slope roof areas, and other vulnerable locations. Drip edge installation, installed correctly, can also act to protect the eaves from water infiltration at the eaves. Additional ice shields prevent water from penetrating back into the building envelope even when ice damming does exist.

 

A roof replacement project should include or should have included these very important aspects to ensure that a quality work product is/was achieved and ice damming potential is minimized. Attention to detail in the installation of all flashings and roofing components also has a significant effect on the performance of the roof system under these extreme conditions.

 

Completely eliminating any possibility of damage resulting from ice damming is difficult while remaining within standard building costs and practices, however, even under severe conditions, if your roof has been engineered and installed with care, detail and in accordance with the building codes, the chance of damage should be greatly reduced.

 

For existing roof systems, prevention is also possible. Several measures can be taken to reduce the chance of ice damming. Seal all attic penetrations, for example, around bathroom exhaust fans, plumbing vents, electrical wiring and outlets, with caulking or weather stripping. This helps reduce the heat loss into the attic space. Vent all exhaust fans (bathroom, etc.) outside through the roof. Install an appropriate amount of insulation in the attic. As stated earlier, upgrade to adequate and effective ventilation. Cold air should completely engulf the underside of the roof above the insulation. If there are hot spots, these are the areas that need to be addressed. This ventilation includes not only soffit and roof vents but pre-formed baffles to ensure attic insulation does not block ventilation paths.

Humidifier Maintenance
Tips for maintaining your whole house humidifier.
Read More...
Silicon Caulk Application
How to replace silicone caulk.
Read More...
Water Heater Maintenance
Water Heater Maintenance
Read More...
How To Prevent Termites
Although termites are more common in older homes, termite control can even be a problem in brand new homes. When builders clear trees from a site to build new homes, the termites can migrate to the wood stored on the site. A concrete slab or brick construction is no guarantee that termites will not eventually invade a home because termites can work their way up through the ground into minuscule cracks in the concrete
Read More...
Common Defects
With common issues it's typically a matter of a relatively simple fix to correct the issue, however left alone some of these issues could result in easily avoidable larger issues down the road. While conducting my home inspection I feel it's my job...
Read More...
Downspout Extensions
This should have been added to my Common Issues Blog being one of the most common installations. While installing downspouts so they terminate above the roof surface isn't a "defect" I always recommend routing downspouts to the gutter...
Read More...
Dryer Vent Safety
Clothes dryers evaporate the water from wet clothing by blowing hot air past them while they tumble inside a spinning drum. Heat is provided by an electrical heating element or gas burner. Some heavy garment loads can contain more than a gallon of water which, during the drying process, will become airborne water vapor and leave the dryer and home through an exhaust duct (more commonly known as a dryer vent).
Read More...
Electrical Safety
Electricity is an essential part of our lives. However, it has the potential to cause great harm. Electrical systems will function almost indefinitely, if properly installed and not overloaded or physically abused. Electrical fires in our homes claim the lives of 485 Americans each year and injure 2,305 more. Some of these fires are caused by electrical system failures and appliance defects, but many more are caused by the misuse and poor maintenance of electrical appliances, incorrectly installed wiring, and overloaded circuits and extension cords. Some safety tips to remember:
Read More...
Environmental Concerns (Asbestos)
The Ancient Greeks named the mineral asbestos, meaning inextinguishable. Apparently even the Greeks were aware of the harmful properties in asbestos and the effects of breathing asbestos dust. The Greek geographer Strabo and the Roman naturalist Pliny the Elder mentioned a sickness common with workers who created cloths using asbestos fibers.
Read More...
Galvanized Steel Plumbing
Where water pressure is poor in the distribution system, the most common cause is corroded galvanized steel. Galvanized plumbing can close down so that the inner diameter is reduced to 1/8” or less. The only solution is to replace the plumbing lines, typically with copper.
Read More...
High Efficiency Lights
Environmentally friendly lights/Mercury Vapor.
Read More...
Inspect Before Listing
Having a pre-list inspection will give the seller the opportunity to repair or upgrade those items that will no doubt be pointed out during the purchase inspection. Being able to limit the number of items needing attention will increase the marketability of the property being sold.
Read More...
Radon
Radon, because it is a gas, is able to move though spaces in the soil or fill material around a home's foundation. Michigan homes tend to operate under a negative pressure - this is especially true in the lowest portions of the home and during the heating season.
Read More...
Sump Pump Operation
Sump pumps are self-activating electrical pumps that protect homes from moisture intrusion and are very common in Southeastern Michigan homes. They are usually installed below basement or crawlspace floors to remove rising groundwater and surface runoff before it has a chance to seep into the home.
Read More...
TPR Vales and Discharge Piping
TPR (temperature pressure relief) valves are safety devices installed on water heating appliances such as boilers and domestic water supply heaters. TPRs are designed to automatically release water in the event that pressure or temperature in the water tank exceeds safe levels.
Read More...
Aging in Place
"Aging in place" is the phenomenon describing senior citizens' ability to live independently in their homes for as long as possible. Those who age in place will not have to move from their present residence in order to secure necessary support services in response to their changing needs.
Read More...
Ash Tree Enemy
Damage to Ash trees throughout the United States.
Read More...
Bats in the attic
Bat guano can build up in attics and eaves that have been used by bats, and even if the human occupants of the building are not aware of the dung, they may be harmed by it.
Read More...
* Indicates required questions
Name *
First Last
Email *
Phone # *
Property Address (Include City) *
How can we help you?
VerificationCode
Enter code in image: