6 Ways to Prevent Ice Dams Now
Brought to you by Hingham Realtor Alice Pierce
Rows of icicles hanging along the eaves of your house make the occasional doldrums of a New England winter more enchanting and wondrous. Aside from the sparkle that icicles add, these iridescent spears are also a clue that you might be cultivating ice dams. Ice dams occur because of there is an ongoing build up of ice on the roofs of homes and buildings.
The same set of conditions that create icicles, also create the thick and stubborn ice ridges along roof eaves that block the water drainage from melting snow. When the water run off has no place to go, it eventually freezes up again once night time temperatures set in, adding another layer of ice to the “dam.”
It is not the ice dam itself that causes damage. Rather, it is the blockage of water by the icy build up. When water cannot escape, it leaks through the roof before the temperatures drop and freezes what water is there.
Ice Dam Dynamics
When snow melts on the slope of a roof, the water flows down the roof underneath the insulating blanket of snow, and then freezes again once it is exposed to the air. This is because the air is colder than the temperatures underneath the snow cover. Ice accumulates where the water emerges from under the snow and forms an obstacle, preventing any water from draining properly. The frozen dam forms on the overhang of the roof because that area is not likely to be exposed to the same indoor living temperatures that it is on the roof itself.
Once this dam forms to a certain height, the melted snow that pools up behind it can suddenly leak back under the roof shingles and into your home! On a roof with a low slope, it only takes a small ice dam to cause water backup and leakage.
The warmer your attic is, the more melting occurs on your roof. Most melted snow flows over the roof edges, but when the air temperature is extremely low, the water refreezes at the edge of the roof, where the interior roof surface is not being warmed by the attic. It is the constant cycle of refreezing that gradually forms the dam of ice.
Damage caused by ice dams can run deep and be a huge expense. Roofing materials are often compromised, ceilings and walls damaged, insulation soaked and the very structure holding up your roof can eventually become unstable. It is also possible to lose gutters and shingles, or cause water to back up and pour into your house. Then you are looking at peeling paint, warped floors, sagging ceilings, soggy insulation and the potential for mold and mildew.
How to Prevent Ice Dams
Understanding the dynamics of ice dams can help you take preventative measures before the cold weather and snow arrives. Here are some of the necessary conditions needed for ice dams to form on your roof and possible remediations.
1) Type of Roofing Material and Installation
Roofing material is often black, and this attracts the heat causing a more rapid melt. But that in and of itself is not enough to cause ice dams. If it were, 99% of all homes and buildings would fall prey to them. One reason you see metal roofing is because its slick surface prevents ice dams from having a way to attach. This is usually reserved for commercial buildings.
A quality roof installation should have proper flashing, ice and water barrier installed on roof edges valleys, rolled asphalt underlayment over the entire roof, and quality roofing shingles with the proper overlap.
2) Attic Insulation
An inadequately insulated attic space is a key factor when it comes to the formation of ice dams. A lack of attic insulation allows more of the heat to escape upwards across the entire surface of the roof, heating the snow more than normally from underneath. If your attic is warm and toasty, then you might want to consider some measures to keep it cold.
To take some preventative measures now, make sure that your attic is insulated sufficiently and properly. Insulating your attic floor is a strong preventative against ice dams.
Sometimes when insulating an attic floor, the material is pushed deep into the corners where the roof meets the attic floor. This will cause the lowest part of the roof to be colder than the rest. If you see that this is the case, simply pull the insulation away from the inside of the roof so air can reach it.
If you have blown-in, loose insulation, purchase some styrofoam dams to install between the floor joists to hold the insulation back from the inside of the roof. Also check your soffit vents as insulation should not block the flow of cool air up from the soffit to the ridge vent.
Otherwise, for spotty insulation, simply lay additional batts across the existing ones, or on top of your blown in insulation until you can have more installed.
Keep in mind that once you reach your area’s optimal R-value (a measure of the insulating value of a material), further increases in the amount will not show appreciable decrease in heat loss per dollar spent.
You may also install weatherstripping and insulation on attic stairways and on attic floor-mounted louvers for whole house ventilation fans. Be mindful of any exposed recessed light fixtures or vent fans since these are not designed to be covered with insulation.
3) Attic Ventilation
If there is no ventilation installed in your attic, either mechanical or structural, then the heat will build up more and make your roof hotter than it needs to be. The installation of mechanical or structural ventilation to allow hot air out through an opening in your roof can help, even if your insulation is thin or patchy.
Even with a perfectly insulated attic space, there is still heat leakage into the attic and a build up in temperature, but ventilation will address that. You can widen existing ventilation, and you can also add vents into soffits (where the roof overhangs the house walls). Ridge vents are an excellent type of ventilation as well.
Ridge venting is a specialized vent installed on the peak of your roof so that cold air entering the soffit vents rises along the inside of the roof and exits through the ridge vent, cooling the roof.
Temperature is another contributing variable to ice dams. If your attic temperature is above 30 degrees, and it is 22 degrees or lower outdoors, then you have a recipe for problems. Think of it this way; you want to have as cold a roof as possible, while still ensuring that your indoor attic space is insulated enough to keep the cold from seeping in.
5) The Presence of Snow
The presence of snow cover on your roof is another factor in the production of ice dams. There is a special tool called a roof rake which is basically a wide edge attached to a very long pole. It will only work on the lightest snow.
You might think that only the lower parts of the roof need clearing off but this is not true since shoveling part way causes the ice dams to form where the snow remains. Raking can help slow the build up of the ice dams but be mindful not to cause damage to your roof.
6) Clogged Gutters
When it rains, gutters are designed to efficiently funnel the precipitation through to your downspouts and ideally away from your house. Your gutters do not know the difference between rain and melted snow, but if leaves, pine needles, and twigs have clogged up your gutters, the water is more likely to adhere to this debris and freeze.
Any water run off from melting snow will add layer upon layer of ice to your gutters, and eventually add to the ice dam problem. Standing water in gutters freezes during colder temperatures and this forms long blocks of ice which obstruct all water flow. Because the ice weighs more than moving water, the additional strain of weight can cause them to buckle, dislodge, dent or separate.
In spite of what we hear, clogged gutters are never the direct cause of ice dams, they simply are one of the many factors that spell ice dam disaster.
What if it’s too late?
If snow has arrived and you find that the ice dams are already forming, here are some measures you can take for the short-term.
1) Make grooves
By chiseling grooves into existing dams you can free up the water so it will flow down and off the roof. This is not to be taken lightly because many people have damaged their roofs this way. It is an excellent emergency measure though.
This can work for smaller ice dams only because if the dam is too big you may increase the pool of water behind it. By filling up pairs of pantyhose with calcium chloride snow melt and laying it across the dam itself, you will help create a channel for the water to flow. Do not ever use rock salt since that will surely stain your siding and the roof.
3) Heat up your attic
Heating the attic may help for the short term even though it is counterintuitive. This is an emergency measure and not something you want to endure. Before allowing your attic to heat, make sure there is a path for the melting to snow to run off.
Keep in mind that even if you follow all recommendations, ice dams might still form under severe conditions.
Fall is an ideal time to start looking for homes in Hingham MA. There is no better Realtor to show you what the South Shore of Massachusetts has to offer than one of the South Shore’s top real estate agents, Alice Pierce. Alice is native to Hingham MA and can talk to you about Hingham’s neighborhoods and their distinctive characteristics, as well as Cohasset, Hull, Scituate, Norwell, Hanover, Marshfield, Duxbury and all of the South Shore towns.
You can also call her cell phone at 781-724-7622 anytime, night or day.