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ice barriers / ice dams

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Guest User
6/19/2004
this house of my friends that im fixing for him to sell (he's in africa trying to save the world) has a peak and valley----at the end of the valley (bottom) is where the front/ main entrance is as well - so on both sides of the valley there are metal barriers perpindiculare to the roof sticking out 3 inches to stop the snow buildup from sliding on anyone walking in or out of this entrance... problem is that an ice dam formed this last winter because the snow was piling up on these barriers and then leaks started to happen for obvious reasons (the ice dam and its by-product)and ruined a header right below this valley -- anyway--- should i take these bariers out all together and allow gravity to take the snow down even though it may land at the entrance---- (i have photos if anyones interested) or re-aim the barriers so that they use gravity (right now the are parralel to the eaves) ...this is in cowboy country in canada--- so its long winters.... the roof itself is blue dark blue, and so it seems a bit warm in there (there is a fan venting and since there is no tarpaper, no poly, just insulation raftersand the metal roof i figure ventilation seems to be as good as possible---insulation is probably 2o inches or so. any ideas to help me --- i am taking a week off work to help him out and get this done .... any advice would be appreciated.
Guest User
6/20/2004
Adam, Valleys are tough areas because of the way in which snow converges from both sides. However, I would remove these metal pieces at the bottom and not do anything to discourage the snow from sliding at that point. Higher up on the roof, above the valleys, snowguards might help by somewhat slowing down the snow as it slids toward the valley. This can help keep it from compacting so badly in the valleys. You could also consider heat tape fastened to the roofing above the overhangs. Also, I am unclear on how/whether the airspace beneath and above the insulation the roofing is truly vented with intake and exhaust vents.
Guest User
6/21/2004
I have a pitch change on a metal roof, and it is aggravated by the fact that the upper steeper pitch is warmer due to the fact that it is on a urethane foam/OSB roof panel. The lower roof section is flatter and cold as it only covers a deck area. The joint is over the upper roof panel area, and has had ice buildups at the joint area, allowing water into the joint. It then drops onto the underlying roof panel, and can find a way into the housing panel or interior, or under the stucco exterior of the wall. I originally thought the metal would shed the snow, but it has a tendency to stick when it sags to the cold metal area. Is the only solution a bitumen barrier under the first 2 or 3 feet of upper pitch and full extension under the lower pitch deck roof (which would require removal of the metal roof and OSB sheeting where it is currently only strapped)? Is there a joint sealant product that would withstand the -50 to +85 temperature changes? The roof material is a 5 rib 32" sheet with anti-wicking lap seams. Obviously the latter would be preferable, but I would rather not have to repeat any repair process every two or three years.
Allan Reid
Dura-Loc Roofing Systems, Inc.
6/22/2004
Unfortunately you are in a situation where the metal roof sheets were looked to to correct other issues. The building code calls for a vented space above the insulation of at least 1". This will help keep the upper roof cooler and stop the differential melting of the snow. Further when one has a steeper roof over a heated area transitioning onto a lower sloper roof over an unheated area such as a porch, it is a recipe for ice and water daming regardless of roof material. The proper way would have been to install an ice a water peel and stick underlay on the lower roof and up the transition on the steep roof until a pointv 3" inside the exterior wall. Use a good quality underlayment on the balance of the upper roof, taping the penetrations. The strap the roof vertically over the rafters with a 1" board and then horizontally to the manufacturers specifications to accept the metal. Use vented closure strips at the eaves and ridge to provide the required ventilation. At the transition, make sre there is an adequate metal flashing from under the upper sheets onto the lower sheets. Short of removing the roome and replacing it correctly, you could try installing a heat cable on a thermostat that will come on in the cold weather and melt the ice buildup.
Guest User
6/22/2004
I live in an area that gets a lot of snow in the winter. I have a metal roof which sheds the snow well. The problem is that I have a short overhang on the house so the snow piles up close to the house on both the front and back sides. In addition to being a problem keeping the walks clear, when the snow melts it is so close to the house that it tends to run water under the house in the crawl space. I've seen some building in the area with ice dams on metal roofs. Would you recommend installing snow/ice dams on my roof?
Guest User
6/23/2004
I have a metal roof (standing seam type - I don't know much about them), and when it was installed I asked to have some type of guards installed to prvent the snow sliding off the roof and possibly hurting someone. My contractors glued some plastic ang;e pieces, about6 or 7" ;ong - 1 each between the ribs. They alternated in height from the roof's edge, the closest 12-18' (est) and the farthes about twice that. Most of these have come off due to wet, heavy snow. After the first time, I had them replaced, but they came off again. The glue is still on the roof, however. Is there another, better method? Even when the guards were in place, the ice and snow got hung up on the gutters and created a hazard. Are there special gutters for this type of roof as well? Thanks for your help.!
Allan Reid
Dura-Loc Roofing Systems, Inc.
6/25/2004
One of the good things about having a short overhang in cold climates is that it cuts back on the chances of ice damming. If the shedding snow does not bother your entrance, then I would suggest that you not install them and look at changes in your landscape that would passively deal with the water.
Allan Reid
Dura-Loc Roofing Systems, Inc.
6/25/2004
This is unfortunate and it sounds like your contractor did not have detailed experience in this regard. First thing is to contact the roofing material manufacturer and get their advice. The quantity, spacing and type are dependant on the type of sysyetm, rafter length and roof slope as a steeper slope with a long rafter will have more snow to hold back. Failing this there are a number of companies that manufacturer various types of guards. Try going to one of the metal magazines and get their advertising list. Moderntrade.com, Metalmag.com are two of them that support our organization. As to the gutters, It would appear that they may be installed too high and the snow catches them. They should be installed so that the outer edge is just below the roof plane.
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