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Repairing and Preventing Ice Dams: Interview with William Payne, PE of O&S Engineers & Architects

AHN Repairing and Preventing Ice Dams Article

AssociationHelpNow Issue 5 – DECEMBER 21, 2018

As the seasons change, there is more to think about than how early is too early to hang holiday lights on your roof. In fact, while you’re up there untangling them or digging through the attic for extra bulbs, you should also be checking your roof for ice dams. The forming of icicles on your gutters or roof may look pretty, but it could be an indication of a bigger problem.

Just like leaving a door wide open, heat could be escaping out of your roof. Yet the issue may not be caused by a shoddy roof. To explain how this happens and the ways to combat it, we interviewed William Payne, P.E., principal and vice president of O&S Associates engineering firm in Hackensack, New Jersey.

According to Payne, “An ice dam is the buildup of water or ice that forms along the rake of a sloped roof and crawls up under the roofing or the shingles, causing leaks inside a home.”

How Ice Dams Form

Why do ice dams form? “They form during winter weather through melting and icing or freezing and thawing,” he said. “The cause is poor construction.” Payne said that poor insulation and poor ventilation are the two primary causes of ice damming. “Poor insulation in a roof or an attic causes the roof to be too warm. That tends to melt the snow or rain and then causes it to freeze. Then what can even make it worse is poor roofing membranes or roofing practices that allow the ice dam to build up and penetrate the roof,” he explained.

Although it may seem counterintuitive to have a cool area anywhere in the structure, Payne explained that, “You actually want a cold roof. You want the heat to stay inside the home. When you leak heat, you melt the snow which turns it into water, which then runs down and hits the ice that’s forming and then refreezes.”

According to Payne, the conditions that make it more likely for ice dams to form are “predominantly a phenomenon in the Northeast,” which is due to the fact that there are many freeze/thaw cycles. As far as certain structures being affected, Payne added that, “It has to be a shingled roof. Sloped roofs get it the worst. In addition to that, it’s the roofs that have a lot of features — a lot of dormers, a lot of dips and valleys. They tend to have the problem worse, because that’s where you often have discontinuity in insulation and issues with flashing.”

He continued, “Ice dams need to be able to crawl under a roofing system in order to cause damage. The shingled roof really relies on gravity, because it is not a continuous membrane. It’s the Achilles heel.”

Addressing the Problem

As far as the kind of damage ice dams cause, Payne said, “It destroys your roof. But the biggest problem is that it causes leaks inside.” Yet there is some good news. The site of the damage can often be spot-treated and not require a whole new roof. “Ice dams are usually isolated to certain conditions,” he said.

But a word of caution: a quick roof fix may only be putting a bandage on a bigger problem. Payne said, “Fixing the roof isn’t usually the only solution. Because the underlying condition is going to be air leaks and breaches in insulation that cause that condition to really accelerate. Usually most people’s approach to ice dams are to fix the gutter and fix the roof. But that’s not really addressing what’s causing the ice dam to begin with.”

According to Payne, board members and managers should be on the lookout for icicles as a warning sign of a potential ice dam problem. “You’ll see icicles forming. That could also be a gutter problem. A lot of times gutter problems are related, because sometimes the gutter can contribute to the ice damming of a roof. Gutter icicles will create that initial ice dam, then it will continue to crawl up the roof. If the attic is too warm, that means that too much heat is leaving the conditioned spaces, and that creates the conditions for ice damming.”

So how should association managers and board members address an ice dam problem? “Usually we get a call that there is a leak that only happens in the wintertime. Chances are that if it happens to one home in the community, there are other homes that are at risk for it, because the homes are built by the same people. Once that happens, it’s time to look at the condition of the gutters, the conditions of the roofing and the conditions of the insulation,” Payne said.

Preventative Maintenance

What is the typical process for addressing an ice dam problem that becomes reoccurring? “You have to do a study that really goes beyond the roofing. We have had conditions where we have had to use air barriers and insulation and spray foam to keep the roof a little colder so ice dams don’t form,” Payne explained.

Payne also suggested that diagnostic tools can help locate problem spots ahead of time. “Basically you are tracing the energy efficiency of your home in terms of insulation in your attic. You can do blower door tests or use infrared thermography to look at your roof to find warm spots on the roof, and correlate that with other observations to help determine the risk for ice dams in the winter,” he stated. Payne is quick to point out that this is not just a winter project. “You can study in the fall how the temperatures are dropping. Once the heat goes on, you can look for warm spots on your roof.”

So what can be done to prevent ice dams from forming? “When you do a shingled roof, people will specify they want an ice and water shield, which prevents the ice dams from going through the roof. But it doesn’t prevent the ice dam from forming,” explained Payne. “You can often re-roof or flash a roof to prevent the ice dams from penetrating into the roof and into the interior of the home, but it would be better to solve the insulation and the air barrier issues that are causing the ice dams to form.”

Payne is also a proponent of state-of-the-art polyurethane spray foam to combat stubborn corners of the roof. “Often spray foam is best to utilize to get into those crevices that are hard to reach, where you have a lot of air leakage. In old homes, the rafters sit right on the top plate of the wall. It’s very hard to get the thickness of insulation there. That’s why a lot of older homes develop ice dams; they don’t have the energy truss to allow the insulation to go all the way over the top plate of the wall. They can spray in polyurethane spray foam to those areas where normal roll insulation or blown insulation won’t fit,” he said.

Payne offered some final words for those dealing with ice dams: “If there’s one takeaway for people that don’t understand ice dams, it’s that a better roof isn’t necessarily your best strategy. Look inside to the insulation to find out where you are leaking air and heat.” He continued, “Also, there are new insulation technologies today to help address those conditions, so more than preventing ice dams, you are also making your home more energy efficient. Ice dams might be a great way to look at the overall energy performance of your home.”