|Source: The Daily Apple|
We must have had just the right weather in Minneapolis because icicles have started to form all over houses in our neighborhood. As pretty as they are, they pose a pretty big threat - ice dams. An ice dam forms when snow melts off a warm roof but freezes as it reaches the eave (overhang). The ice builds up and the melting snow forms a little lake behind the ice. It's not a lot of water but it's enough to creep back up under the shingles and eventually run down into the walls and ceiling. This image from homeconstructionimprovement.com illustrates an ice dam.
There's evidence of water damage from ice dams in the past in our living room and foyer.
|Water spot around the crown molding|
|The wall is bowed from water above the front door and window|
We hadn't seen any problems until just last weekend. The temperature was above freezing and we were greeted by drips of water coming from the window frame and door frame. Yikes!
|Icicles on the inside of our door frame|
|Ice in the bottom of our door - which froze shut|
Our neighbors told us that previous owners in the 90s spent a lot of time trying to figure out a water problem coming from the roof. Supposedly they fixed the problem but clearly there's still water coming in by this door.
How to fix Ice Dams
If both the roof and eave are cold, the snow stays frozen and doesn't cause a problem. If both the roof and eaves are warm (like in the spring) then the snow melts but runs right off the roof. What you don't want is a warm roof and cold eaves. To fix this you either need to make your roof colder, your eaves warmer, beef up your roof's defense against water, or get rid of the snow all together so there's nothing to melt.
Keep your roof colder
The reason the roof is warm is because there's not enough insulation - or none at all. If you look around your neighborhood and see snow on your neighbor's roofs but not on yours, you probably don't have insulation. If you have snow on your roof except for a few patches where it's melted, those patches are the places you don't have enough insulation. Better roof ventilation can also solve this problem by allowing cold air to circulate through the attic and keep the roof cold. We have pretty good insulation,so when there's snow on the ground, there's still snow on our roof. Our insulation compares well against neighboring houses so it's not our inside heat that's melting the snow on our roof and causing the excess water.
|How ventilation keep the roof cold.
Keeping your eaves warmer
Another remedy is to keep your eaves warmer so the melting snow doesn't turn to ice. You can buy heated de-icing cables that run along the edge of your roof and down the gutter. It keeps that section of roof warm and keeps ice from forming.
These might work but they don't solve the bigger problem - heat is escaping your house through your roof. It's a bummer if you're paying for heat that's floating out the roof but it's a bigger bummer to pay for more heat to keep the eaves warm. Since we're not loosing a lot of heat from our roof, we might try to install these this summer in some key spots to see if this helps next year.
Beef up your roof's defense against water
There's a product called "Ice and Water Shield" that you can have installed when you're having your roof replaced. It's a thick, sticky, waterproof barrier that makes the bottom few rows of shingles totally water proof. You can have standing water backed up from an ice dam and nothing will get into your walls and ceiling. We mentioned our previous owners did something to fix the water damage, I'm hoping this is what they installed. Unfortunately, if they did not, we probably won't be doing this any time soon since the roof is new enough that we don't want to mess with it.
Get rid of the snow all together so there's nothing to melt
Finally, if there's no snow to melt, there's no possibility of water freezing. You can buy long (like 20 feet) shovels that are designed to pull snow off your roof. We found one in the garage after moving in (yay for free stuff!) so I broke it out. Our roof is well insulated so we shouldn't have major problems with ice dams... fingers crossed. Our best line of defense right now is just to minimize the amount of snow on the roof.
|My what long... shovels you have.|
|"Reach for the sky!"|
Even with these defenses there are times when the weather is just right for making ice dams. On a 32° day with lots of sun it's almost inevitable. We'll see how many water problems we have when spring hits. Our plan for now is to keep shoveling the roof (only in Minnesota would you hear that...) to minimize the amount of snow that can melt and cause problems. We've discovered that the tree in the front yard which we already don't like (blocks light and pathway to the front door and is kinda overgrown and ugly) makes this shoveling process extra difficult. Looks like we have another project for the spring! Oh the joys of owning a home.