How To Prepare Your Roof  & Safely Remove Ice Dams This Winter Season

Roofing is seasonal work that is heavily dependent on the weather. Typically, the roofing season runs from early May to late November before snowfall and cold temperatures hit the east coast. However, the start of December 2014 was unusually mild, which gave our roofing crews the hope of a longer working season. Ironically, our crews did spend most of the winter working on rooftops but not because the weather was nice.

The east coast spent much of the winter beneath record snowfalls. In addition to the mounds of snow, the east coast also experienced temperatures that frequently danced around the freezing mark. The mix of snow, warm temperatures changing to below freezing temperatures, as well as the heat generated indoors, made for ideal ice dam formation conditions. Last winter, many homeowners were faced with this problem and didn’t know why ice dams were forming or what they could do to fix it. In preparation for this winter, I’ve outlined below what every homeowner needs to know about ice dams, what they can do, and more importantly what not to do.

What is an Ice Dam?

An ice dam is a build up of snow and ice that prevents water from running off of a roof. When snow and ice begins to melt a pool of water is formed and blocked by an ice dam. The accumulation of pooled water can then leak through the roof decking via nail holes, screw holes, or any other penetrations found. Once water has penetrated through roof decking, homeowners run the risk of water damage, rot, electrical issues, and a number of different issues.

How Does This Occur?

Ice dams occur when an attic space generates enough heat or, warm temperatures to melt snow on a roof. The melted snow runs down to the bottom section of the roof, also known as the overhang, which typically has no attic space below it. The ice dam then begins to form when the water from the melted snow contacts the snow and ice sitting above the overhang.

Why Does This Occur?

Insulation: Insulation is designed to keep heat in the living areas of a house during colder months and also keep cool air in a house during the summer. However, insufficient insulation can let warm air escape into the unlivable areas and air spaces found in a home. You can imagine the amount of heat generated by day-to-day appliances like an oven, dishwasher, or dryer. Not to mention, homeowners also spend money to run furnaces, fireplaces or electrical heat. Without proper insulation a lot of that generated heat makes its way into the attic, which then contributes to the formation of ice dams.

Ventilation: Ventilation is not something many homeowners take into consideration when making sure their house is ready for the winter. Ventilation is designed to ensure the temperature of your attic space is identical to the temperature outside. Typically, homeowners don’t realize they have insufficient ventilation until an ice dam has already formed. To ventilate an attic properly, two components are required. The first is the intake, which are vents located at the down-slope edge of the roof (eaves). The intake allows fresh air into the attic. The second component is the exhaust, which is located near the ridgeline of the roof. The exhaust allows air to leave the attic (ridge vent). The use of an exhaust vent in conjunction with an intake vent uses the natural forces of wind pressure and thermal effect, collectively known as the Stack Effect, to ventilate the attic space.

Here’s a look at the numbers: For every 300 square feet of attic space, one foot of ventilation should be installed. Fifty percent of that ventilation should come from the bottom of the roof and fifty percent should be at the top. It is important to note that having a ridge vent without an intake vent will not provide sufficient ventilation. Yes, some heat will escape, but a lot will still be trapped in the attic space especially near the bottom (where ice dams form). It is also important to note that multiple types of ventilation in the same air space can actually be counter-productive. A common error we run into is seeing homes with gable vents (vents in the siding near the top of the house), ridge vents and soffit vents. When this happens, the ridge vent draws air from the gable vents as an intake, not the soffit vents. When the air is not drawn on from the soffits then pockets of heat can form near the bottom of the roof and cause ice dams. Similar to this is having a turbine vent and ridge vent. The turbine vent will draw its air from the ridge vent not the soffit. Homeowners should also note that just because a house appears to have a ridge vent does not mean the vent is working properly.

Our crews have run into many cases where homes have ridge vents installed but the hole for the air ventilation is not big enough. Our crews have also come across a number of roofs that had ridge vent but didn’t have a vent hole cut. If you are unsure whether your ridge vents are installed properly or have any questions about your current ventilation set up, arrange a roof inspection.

Other causes of ice dam formation

Slope: Roofs with a low pitch are more susceptible to ice dam formations. It is important to note that shingles are not designed to stop water; they are designed to re-direct it. Therefore if an ice dam traps water, the shingles cannot function as designed. Different materials are required for a lower pitch roof. If the wrong materials are used your roof could be prone to reoccurring leak issues.

Roof design: Roof design is another huge determining factor for the development of ice dam formations. If you have multiple dormers or runoffs leading to the same area, or slopes leading into walls then you may be at risk for ice dam formation zones.

Clogged gutters: Our crews have seen a number of ice dams that have started due to clogged gutters. This is an important reason to ensure your gutters are clear of fall leaves before winter hits. What To Do If An Ice Dam Has Already Formed: Each ice dam is unique. Some can be easy to deal with and some require more work. The best way to avoid an ice dam is to prevent snow from building up.

One thing that homeowners can use to prevent build up is a snow rake. Snow rakes are long rakes that allow you to remove the snow from a roof while standing safely on the ground. Snow rakes are available at most hardware stores. However, if you have an ice dam it is recommended to seek professional removal help.

What not to do if an ice dam has already formed

The number one mistake a homeowner can make is putting salt on a roof. Yes, it will melt the snow and ice but it will also melt the roof shingles. It is recommended that you use calcium chloride instead. It will have a similar effect except calcium chloride is better for your roof. Calcium chloride is a supply that a homeowner should stock up on as it regularly become scarce after a big storm.

The best piece of advice for dealing with an ice dam is to call in the experts when in doubt. Even in the best of conditions without elements such as snow, ice, and wind; a roof can be a dangerous place and a fall can result in serious injury or death. Our crews use a combination of harnesses, ropes, fall-prevention systems, and rescue plans to ensure all jobs are completed safely and correctly.

Stay warm this winter!