Ice Dams

I'm taking a little break from computer technology today to pass on what I have learned about ice dams. I own an older home which was not designed to keep the various parts of the roof cold. Therefore I have ice dams, which is when water backs up into your home when it gets trapped behind ice which build ups at the roof's edge because the eaves (edges) are colder than the rest of the roof.

I have had the home about 6 years now. Several years ago, I didn't know what ice dams were. I thought the hanging icicles looked great. Then some water backed up into the roof, along a seam and down a wall, across a poorly-grounded electrical switch and caused a house fire. Thank God there was relatively minimal damage. An electrician repaired the wiring. A roofer flashed and re-shingled half of that particular roof. I repaired and repainted the wall and ceiling damage.

I did a lot of reading about ice dams at the time, educating myself. In the end I decided to get a roof rake, to try to prevent ice dams from forming by keeping the snow off. It's literally too much work to clear all the roofs with it, so I try to get at least the last 4 feet, which is recommended for ice dams.

I thought that was working well until last year, when I again had some water leaking into my house, in a different place this time (right where the computer was!). Basically what had happened was that sometimes storms come in such a way (such as an ice storm followed immediately by snow) that even with roof-raking, the roof will not be clear at the eaves, and then the ice dam forms. I assumed as long as I kept the roof raked, thereby minimizing the material there, that everything would work out. I was wrong.

I ended up putting up a ladder in the snow in middle of the night in freezing weather, and climbing up to chip channels in various spots along the dam, letting the water out. Cutting channels was an emergency method my dad had heard of. It was supposed to be much more effective, easier on your roof, and safer, than trying to clear all the ice. Once the channels were clear and running I kept them clear with liberal applications of calcium chloride. (Sodium chloride should never be used for this by the way, as salt will damage your roof, your home, and any vegetation below.)

Fast-forward to this year. The ice-followed-by-snow scenario took place again last week. I had two leaks in the same week this week, one in the place where we had the fire, and one in the same place as last year. I handled both with the emergency channel-chipping method which so far appears to be successful in stopping any further damage or leaking. But it looked like it was time to re-google the current state of ice dam technology.

Here is what I have learned. There are several ways to go at the problem, all with pluses and minuses, which I will attempt to enumerate here. Suffice it to say the first ones are very expensive and intrusive, with the benefit of needing less or no maintenance. Effectiveness is really going to depend on specific circumstances as best as I can find out. If your solution is well designed, and implemented by an expert, you could have great results. However if either the architect or the builder is uncommitted or inexperienced, good intentions and lots of money mostly likely will not bring success. It has to be said that baking this into a new home is far preferable to retrofitting an older one. The last solutions are cheaper and less intrusive, however they involve lots of maintenance, and wear on your roof. As reactionary measures, rather than preventative ones, they are naturally less effective.

(1) Redesign your house. This is the only truly preventative measure, and even so it is not guaranteed to work. The idea is to create an area above your heated living areas that is unheated. Your new roof goes on top of that. Ice dams do not form because the roofs thaws evenly. Obviously the drawback is expense. The benefit is no further maintenance required. Theoretically there are weather conditions which are impossible to engineer against, but there are edge cases for everything, and emergency methods should help prevent permanent damage.

(2) New roof with a moisture barrier. There are standard products and methods available now to put a waterproof membrane under your whole roof. The drawback again is expense. The benefit is it should be cheaper than option 1 while still calling for no maintenance.

(3) New roof with a ventilation layer. The idea is this is a retrofit way to accomplish the best possible scenario, a cool roof. The technology appears to be fairly new, and fancy (as in perhaps a little complicated to implement effectively, in such a way that it would last). However I didn't look at it closely.

(4) Metal roof. I saw mentions of metal roofs, but no explanation offered as to why they would be effective in battling ice dams. I'll be keeping my eye on this, as I also like the sound rain makes on metal roofs! However I have one on my garage, and there are weird weather conditions where it leaks big time through every (rubber-grommeted) nail. This has happened a couple of times, I think usually when there are temperature extremes in the same day (going from way hot to way cold, or the reverse?).

(5) Heat tape. I know people who swear it works miracles. However the comments online and by professionals are universally against it. It wears out quickly, shortens the life of the roof, and while it does melt ice, the ice dam simply re-forms above it on the roof. It is put on in a wave pattern for some reason.

(6) Heat panels. This is something new since the last time I looked. Heat tape is run through aluminum panels attached to the roof at the eaves. I couldn't find any outside evidence of the success or failure of these products, nor could I find any prices. Until both of those exist I'd leave any recommendations to the experts. Here are a couple of examples:
http://www.bylinusa.com/roof_ice_melt/RIM1.html
http://www.thermaltechusa.com/

(7) Roof rakes. There are a couple of variations on the plain roof rake, including wheels and wires and slides. In general, at least in my experience, it is roofs with poor pitch that have ice dams, and I doubt any of these tricks would work on such roofs. One hint my Dad came up with is to buy thick (and lined for the cold) rubber (or plastic?) gloves. There is something about the wet aluminum that easily ruins any other type of glove in minutes. The drawbacks I am seeing with the roof rake are:
-It is ineffective (I am still having leaks).
-It damages the roof. It is amazing how much material I have lost off the shingles.
-It is maintenance-intensive. This easily adds an hour or two onto every snowstorm. And until you have to work with your arms raised above your head under load for an hour, you can not imagine the agony in your shoulder muscles. Then once you are done, all the snow you have brought down is now packed tightly by the fall onto your porch or walk, where it will take many times the effort of initially shoveling those areas, to clear them again.

(8) Ice dam sock. This is my new find! You take nylon panty hose, fill it with calcium chloride (18" long), and tie off the top somehow (velcro seems to be common for reuse). You place it on the roof at and perpendicular to the edge, every 10-15 feet. Refill roughly every 30 days. This creates the channels I talked about before, but instead of being an emergency afterthought, these channels are there draining the roof from the get-go.

Conclusion: I think I had two problem-vectors. The roof rake handled the simple task of clearing snow off of the lower part of the roof to prevent ice dams from forming in most cases. The more complicated vector however, was when despite my best efforts and sometimes as a result of mixed precipitation and weather, I would get ice dams anyhow. I plan to use the socks to handle that vector, creating relief valves in the dams even as the dams are forming. The only thing still to work out is how to roof-rake around the socks!