Put simply, an ice dam is a length of ice which forms at the edge of a roof that stops additional meltwater from being able to drain. Ice dams are formed when lower layers of snow melt, but the meltwater refreezes before it drains, causing a water ‘dam’ which can cause significant water damage.
So know you know the basics behind what is an ice dam and how do they form? Understanding what causes ice dams in the first place will help prevent serious damage to your home.
At Snow Blower Guides, we want to help you recognize the signs of an ice dam on your roof and discuss ways that can help you prevent ice dams.
Contents (Jump to Topic)
What Is An Ice Dam?
What is an ice dam and how are they formed? As mentioned above,an ice dam is formed when the snow melts and meltwater refreezes before it makes it off of the roof. The ice sitting at the edge of a roof will then act as a dam for any additional runoff.
As this process reoccurs over and over, the ice dam continues to grow. Eventually, the melted snow, with nowhere to go, can start to leak through the roofing structure.
If you’re not using a snow roof rake to clear excess snow regularly, you may not even notice it’s happening until it’s too late.
What Causes Ice Dams?
What causes ice dams on roofs is simply snow melting and then refreezing. This is generally from extra heat in your attic causing standing snow to melt before the outside temperature can melt the exterior layers or clear gutters.
There are several elements that come into play when talking about the cause of this melt. Below I discuss the most common elements in greater detail.
Insufficient Roof Insulation
Poor insulation can mean big problems for any homeowner during the snowy winter months.
The lack of good insulation is the biggest reason for heat loss from the attic space and out through the roof.
HVAC Equipment In Your Attic
HVAC (Heating, Ventilation, and Air Conditioning) equipment often releases hot air into the attic space. It is therefore important to ensure that there are no holes for hot air to escape from and that all ductwork and pipes are insulated.
Blocked Gutters / Gutter Guards
Although neither gutters nor gutter guards are causes of ice dams in themselves. However, left blocked or in disrepair, they can become a major factor.
It is really important that any meltwater can easily run down the guttering and away from the roof. Trapped water will inevitably lead to it refreezing and an ice dam forming.
Since recessed lighting is installed into the ceiling, it can raise the temperature on the other side. With certain types of light fixtures and fittings releasing heat energy it is important that you insulate them correctly.
Alternatively, you could use LED lighting which emits very little heat and is also extremely cost-effective.
Heat from Chimneys
The warm air that escapes from a chimney stack will have just the same effect as the warm air from the heating exhaust system. Sadly, if you have real fires then there is not too much to be done other than to ensure that your attic is well insulated.
Keep an eagle eye on the roof area closest to the chimney. If you see signs of melting snow then be sure to look out for the start of an ice dam at the roof edge.
How Ice Dams Form On A Roof: The 4 Stage Lifecycle
Stage 1: The Foundation
Once warmed by heat sources in the living space, heat transfer from the attic will quickly warm up the underside of the roof deck. Once the outside roof surface warms up it causes the underneath snow layer touching the roof, to melt.
Stage 2: The Melt
As the roof warms and the snow melts the meltwater starts to run down the roof. When it reaches the edge of the roof, which is cooler, it then refreezes.
Stage 3. The Build-Up
This is what causes ice damming. The eaves are away from the warm roof area and remain icy cold and with winter temperatures reach the freezing point of water. As well as the freezing cold eaves, this can also be caused by blocked gutters/gutter guards.
Stage 3: Game Over
As a larger ice dam forms at the edge of the roof, meltwater will work its way underneath the roofing material. Ice dam damage can cause sagging ceilings, warped floors, and other structural hazards.
What Damage Can Ice Dams Cause To Your Home?
You have probably heard that ice dams can cause significant damage to your home. But will an ice dam always cause damage? No, not if you notice the warning signs early enough, as you may be able to prevent a disaster from happening.
An ice dam can cause severe damage to the gutters themselves if the ice buildup gets too heavy or create ever-widening cracks in the joints. In addition to that, should runoff water manage to penetrate the roof shingles and refreeze, it can seriously damage shingles.
Not to mention peeling paint, and water stains on the walls, or ceiling. Be that as it may, the worst scenario would be the roof sagging or even collapsing under the weight of a huge ice dam. Check out my other guide if you would like to get more information about how much snow a roof can hold.
Preventing Ice Dams From Building Up
Preventing ice damming is far from being impossible – you can take measures against it and save yourself from ice dam removal or repair bills. In fact, I’ve done an entire article dedicated to ice dam prevention so be sure to give it a read as well.
Although there are various ways to remove excess snow from the roof after a heavy snowfall. For a single-story home, a roof rake is a great tool that prevents melting snow from building up. If this sounds like what you need, I’ve rounded up the best snow roof rakes in another article.
Next up is clearing out the gutters to allow any runoff to flow easily away down the drain.
Overall, the more permanent structural solutions include adding insulation to the roof and attic floor. Also, insulate plumbing pipes and heating ducts. Fitting a good roof ventilation system, such as soffit vents, etc., will give good air circulation. This will allow cool fresh air in and hot air out.
You can also install heating cables. These do not keep the entire roof warm, but the roof edges and guttering. Please note here that these can be expensive to buy. It is also recommended that you have a professional fit them, more added costs. As if that’s not enough, a lot of ice dam removal experts say that they can be costly to run and inefficient.
If for any reason you have an ice dam then I do plan on doing a blog about ice dam removal techniques very soon. I will update you as soon as I can.
Knowing the answer to ‘what is ice damming and what forms ice dams on roofs in winter’ can save you from serious structural damage. Melted snow that turns to ice at the eaves is a silent disaster waiting to happen.
Remember this, knowing how to remove an ice dam yourself is not only difficult it can be extremely dangerous. While professional ice dam removal is a costly procedure you can do without in the winter season.
People Also Ask (FAQs)
If you have more questions about what is an ice dam on a roof and how to prevent it from happening. These quick answers to some very common questions may help you further.
Does homeowners insurance cover ice dams?
Many homeowners insurance policies do cover damage caused by ice dams, but don’t take this as a given. Be sure to always check the exact terms and conditions related to roof damage in your policy.
How long does it take ice dams to melt?
It can take several hours for an ice dam to melt when being treated by a professional ice dam removal company. However, it is not possible to say how long it takes ice dams to melt naturally, as all situations vary.
Does roof raking prevent ice dams?
Using a roof rake to remove excess snow and clearing out your gutters will both help to prevent the formation of ice dams. However, roof raking needs to be done regularly to prevent ice dams, ideally after each heavy snowfall.
Are icicles a sign of ice dams?
Although icicles look magical, icicles are a warning sign of ice dams. If you think about it, what causes icicles on the roof, melted snow refreezing. If this ice carries on accumulating at the edge of your roof an ice dam will form.