After the last snow event in Lees Summit, I went out into the neighborhood and snapped some pictures. This picture shows a different solution to ice dams than I discussed previously, albeit not a solution your roofing contractor would probably recommend. Recall earlier that I explained that ice dams form when snow melts over the heated area of your house, and re-freezes over the eaves (the edge of the roof that overhangs the wall)? This house provides a perfect illustration of this phenomenon as the roof is completely free of snow until you get to the eaves. And yet there is no ice dam or icicles forming, why is that and perhaps this is a solution that would work for me as well? Obviously the snow melted on the roof, but the snow melted rapid enough and that provided sufficient water flow to prevent re-freezing when the melted snow hit the cold roof over the eaves. That is a lot of heat that is being lost into the framing space under their roof to melt the snow that fast. The water from the snowmelt was flowing like a relative torrent coming off that roof, and there was no chance that it would re-freeze even though the area of the roof that overhangs the wall was cold. Had the snowmelt and resulting water flow been slower, there was significant potential for ice dam to form. While this homeowner doesn’t suffer from ice dam problems, the thought of the cost of their utility bill makes me shudder. If you have this sort of pattern of snow melt, your roofing contractor will probably want to anticipate that the heat loss problem might be solved during the life of the roof and recommend other solutions to prevent or minimize ice dams.
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We have previously identified what ice dams are, how they form, resulting damages, and preventive steps you can take without installing a new roof. However the ultimate fix to preventing ice dams comes when it is time for new roof installation. Preventing Ice Dams – New Roof Considerations Section R806 of the International Residential Code (IRC) for one and two family dwellings, adopted by Lees Summit and other local municipalities, establishes roof venting requirements. Your local roofing contractor should be familiar with, and apply, the IRC roof venting requirements. I like to install both a continuous soffit vent and ridge vent solution. In minimizing potential for ice dams, I had recommended increasing insulation in your attic floor to a minimum of 14” of dense-packed cellulose; this recommendation means I may need to install baffles at the roof edges to ensure that the ventilation air entering through the soffits can reach the attic space. This ensures an entirely passive ventilation system where air enters through the soffits and exits through the eaves. In doing so, the attic space will automatically stay at or near the same temperature as the ambient air, thus eliminating any potential to melt the snow on your roof from underneath and causing drainage. And since your attic is already properly insulated, there is absolutely no downside as it relates to your utility bills. As a benefit, this venting will increase the life of your roof by preventing overheating in the summertime as well. Some may criticize the ridge vent solution and say it will get covered with snow itself, but my experience has demonstrated that passive ventilation prevents snow from building up near the ridge vent to start with, even heavy snows. The second preventative step is to eliminate potential for ice dam damage, if an ice dam would occur. While this is entirely optional, the only time you can install this measure is when a new roof is being installed. And as the cost increase is minimal, I recommend this as cheap insurance. Ice and Water Shield is a peel-and-stick underlayment used instead of traditional roofing felt underlayment. I like to install this so that the Ice and Water shield extends up the roof for twice the distance of the eave depth. If you have a one (1) foot eave, I recommend Ice and Water Shield extend a total of three (3) feet up the roof (covering the eave, and twice the eave depth up the roof). For a two (2) foot eave, I recommend Ice and Water Shield extend a total of six (6) feet up the roof. As Ice and Water Shield comes in three (3) foot width rolls, this would correspond to either one (1) or two (2) passes. While Ice and Water Shield doesn’t prevent ice dams, it does make the roof watertight and prevents damages if ice dams form. This is why I consider it my insurance step; do everything possible to prevent ice dams from forming first and consider this insurance only. Follow these steps, and you can retire your snow rake and enjoy the winter wonderland without worrying about the danger that lurks beneath. In an earlier blog, I explained what an ice dam, how it forms, and trouble it leads to. If you see evidence of an ice dam forming, you need to address this immediately. And this isn’t the time to install a new roof, although when you need a new roof you have additional opportunities to address ice dams. Ice Dams are caused by warm air in the attic melting the exterior snow, and solving this problem is the first step in getting rid of ice dam problems. You need better attic insulation to prevent that heat from your comfy, warm house from getting into the attic space to start with. And this has the added benefit of saving you money on utility bills and making your furnace or heat pump run more efficiently (you are paying for all the heat that escapes). I recommend a minimum of R-50 insulation over your ceiling joists, and this corresponds to at least 14” of blown in, dense-packed cellulose. This isn’t 14” installed height (it is light and airy when blown in), but 14” after settling. This probably corresponds to 18” of installed height. Code minimum in Lees Summit is R-30 for ceilings, and this is insufficient to prevent ice dams from forming. Minimize the warm air escaping to the attic and minimize that snow from melting in the first place. Ice dams are caused when snowmelt from your roof hits the cold area at the eaves of your roof. This cold area refreezes the water before it can drain off the roof. This is a second opportunity in preventing ice dams (some would consider this the first, but insulation can be done from the warm confines of your home and not outside). You want a long-handled snow rake, available at many home improvement stores or through the Internet. Every time it snows, you need to get outside and get the snow off your roof. I wouldn’t worry about all of the snow; I would worry about the snow over the eaves where the ice dam forms. This way, any snow melt that forms over the heated area of your house (although minimized through additional insulation) has a straight (and fast) shot into your gutters, and once it is in your gutters it is off the roof and not causing or perpetuating an ice dam. Lack of insulation isn’t the only common heat source from your living area into the attic space. Do you have recessed lighting (can lights)? People love them; they look fantastic. Builders love them because they are cheap and people love the elegant look. Builder’s grade can lights have a unique feature in that they build-up heat and have to have a way to shed that heat. In doing so, you have to keep insulation at least 3-4” away from the housings, otherwise they overheat. And they also have vented housings. Do you use a chimney starter for your charcoal grill? Once that fire gets started, it creates a chimney effect as heat rises, and fresh combustion air is drawn in through vents in the bottom of the starter. Well, that light bulb in a can light operates the same way; heat (from the light bulb) rises and vents, and makeup air comes from directly inside your house. Every can light you have is approximately one square foot of uninsulated attic, and to make matters worse they also create a chimney effect pulling even more of your heat into the attic space. And what does that heat do? It melts snow, and that creates ice dams. Can lights need to be properly sealed in the attic, and have sufficient insulation around them to prevent heat loss. In Lees Summit, you can plan on using that roof rake several times per year. These are items you can do to prevent ice dams without calling a roofing contractor. What Are Ice Ice Dams? This will be the first in a series of blog topics about ice dams. After we define what ice dams are and how they are caused, I will follow-up with topics on steps you can take to prevent them without installing a new roof, and steps you should consider when installing a new roof. I understand that the answer to every roof problem isn’t, “install a new roof,” as you may have a roof that has considerable service life remaining if you can address some problems. Ice dams are exactly what they sound like; dams made of ice that prevent snow melt from draining off your roof. And this is the problem, they prevent water from draining off your sloped roof and pool water, leading to roof leaks, potential mold and mildew, insulation damage, structural damage, and aesthetic damages associated with large roof leaks. In an earlier blog, I talked about small roof leaks; roof leaks from ice dams are not small. What Causes Ice Dams? After a large snow, everything is so peaceful and snow covered. It is beautiful, the sun comes out, the sky is crisp and clear azure, uniform snow covering that has no markings; truly a winter wonderland. That wonderland can quickly turn though. Trouble lurks just beneath the surface. Heat rises, and heat from your comfy warm house collects in the attic. This heat causes the snow to melt and the sloped roof allows this snowmelt to drain towards your gutters. However, at the edge of your roof, you have an eave that doesn’t have a warm attic below it. The snow doesn’t melt at the eave. What happens when this draining water hits the area of the roof that isn’t warmed? That water freezes, almost instantly, before it has an opportunity to get into your gutter. Do you see that beautiful icicle hanging? That is evidence of what happens when water hits the cold air. And it isn’t just icicles that are formed, you can form a thick ridge of ice right at your eaves. That thick ridge of ice is called an ice dam, and once it is formed trouble will ensue until it is removed. Every time snow melts on your roof and tries to drain, it will run into that ice dam, pool, and ultimately re-freeze. Once an ice dam is formed, it is self-perpetuating. Here in Lees Summit, we have both snow and ice storms that can contribute to ice dams. If you see evidence of an ice dam forming, you may want to call a local roofing contractor to address this problem immediately. Have you noticed any evidence of roof leaks in your house? These are usually telltale signs of ceiling stains on your sheetrock. Here in Lees Summit, our typical heaviest rain season would be April through September, with each month exceeding four inches of rain. Within this, June is our heaviest rain month with typical rainfall exceeding six inches. The problem with roof leaks is diagnosing the source of the leak. To do this, you would normally look immediately above the stain that provided the evidence of the roof leak. But the roof leak could be a good distance from the stain as water has surface tension that can be stronger than gravity. Have you ever noticed beads of water on a leaf after a rainstorm? What prevents gravity from pulling that water down to the ground? You are observing the effects of surface tension. What this means in a small roof leak (all leaks start small) is that the small amounts of water are leaking through the roof and adhering to structural members such as roof joists, roof sheathing material, or plumbing or HVAC vents. Those water droplets will adhere to these materials the same way water droplets adhere to leaves. As these members slope downward, gravity acting on the water droplets coupled with surface tension will cause the water droplets to follow this material as it flows downward. It is only when these droplets get sufficiently large or a dissimilar material “breaks” the surface tension that the force of gravity exceeds the surface tension forces, and this is where your ceiling gets stained. If you notice a small stain on your ceiling, this may be evidence of a roof leak. It’s always wise to have any ceiling stains or leaks diagnosed early as it is usually much less expensive to fix a small leak. If you can’t find the source of the roof leak, call an experienced local roofing contractor based in Lee’s Summit to find and diagnose the leak for you. When you look at roofs in your neighborhood, have you ever noticed some that have black roof stains? Have you ever noticed a pattern on those stains? Have you ever wondered why those stains appear or what causes them? The cause of these black stains is algae. Here in Lees Summit, we have a moisture rich environment that contributes to the growth of this algae. The patterns you see on individual roofs relate to moisture (such as dew) and areas with less sunlight, including north-facing portions of the roof or areas with heavy tree coverage. This algae also travels through the air, so if you notice a neighbor’s roof appears to have this discoloration, it can travel through the air to adjacent houses, and it just might come your way. This algae is mostly an aesthetic nuisance, and should not affect the life of your roof. It can be cleaned with a mixture of tri-sodium phosphate (TSP, available at local hardware stores), bleach, and water. This should be considered annual maintenance as this algae growth will be a recurring problem. You may also notice a pattern where there are no black stains below skylights, plumbing vents, or other areas that have flashed roof penetrations. This is because zinc in the metal flashing is a natural algae deterrent. As rainwater flows over the flashing, it dissolves minute amounts of zinc from the metal and provides a small portion of your roof that doesn’t support algae growth. When you install a new roof, your roofing contractor can provide methods to prevent this algae growth from ever developing. A roofing contractor familiar with the Lee’s Summit, Missouri area will be the most knowledgeable about how much algae growth is usual for roofs in this area, as well as what some other climate impacts on your roof will be. |
Bobby WilliamsWe are an experienced Lees Summit roofing company with over 15 years experience in repair, service and installation. Archives
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