ice dams

[pudgybear]

this will be my 3rd Michigan winter in this house and for the last 2 winters i have had a terrible time with ice dams / ice build ups ! My question is if i turn on my attic exhaust fan to run full time will this equalize my attic temperature enough to eliminate those ice buildups? i was told if i can get the attic temps the same as outside there will be no buildups, any truth to this idea, second question: i was told to run a heating tape in the gutter to prevent this , what do i do just lay the tape in the gutter and plug it in??????

 

[DEnd]

The problem with the attic exhaust fan is that it pulls heated air from you house. I'm not convinced it would help. Whether it does or not depends on the mixing ratio of outside air vs inside air it brings into the attic. Even if it works it is just a band-aide to your actual problem.

Heating tape in the gutter will not fix your ice dams. Heating the bottom 18" or so of your roof will help as it will keep the melted water melted and allow it to drain instead of refreezing and forming an ice dam. Again this is just a band-aide.

Your likely problem is that you have air leaks from your house into your attic. "Plug" the air leaks and your ice dam problems will likely go away (Assuming you have enough insulation). Ice dams only form when the roof deck reaches above freezing, your air leaks add energy to the roof deck warming it in places which allows the ice to melt. That melted water then flows down and refreezes when it reaches the eves where the roof deck is colder. What is your attic like? Is it a truss or rafters? Do you have flat ceilings? Do you have can lights? Do you have attic dormers? What is you snow load? (your building permit office can tell you this)

 

[theoldwizard1]

... i was told if i can get the attic temps the same as outside there will be no buildups, any truth to this idea, ...

Yes. If the roof deck (wood below the shingles) is the same temp as the outside you should get no snow melt. This not easy. It means you need a lot of insulation in the ceiling to prevent heat from rising. Not a perfect solution because sunshine will still melt the snow.

i was told to run a heating tape in the gutter to prevent this , what do i do just lay the tape in the gutter and plug it in??????

No, you zigzag it up on to the roof about 12" and then down into gutter. Instruction on the package.

You need to plug it in the day after a snow storm. Or on sunny days.

The other thing that helps a lot, is to get a roof rake and rake as muck snow off as you can. The remaining snow you can not reach will melt, but there should be sufficient open roof for it to evaporate.

 

[awdblazer]

you say you have an exhaust fan what do you have for intake?
you will just be sucking more hot air from the house if you dont have soffit vents

 

[dewalt378g]

DEnd is on the right track....these are the most common sources of ice damming. If soffit venting, then use insulation baffles in every rafter bay in in the attic where the rafters meet the cjs on the top plate

 

[yeldogt]

Seal up the ceiling under the attic -- you may have to hire someone to do it correctly. If you are getting ice damming ..........heat is escaping from the house ,, a lot of heat

Is it only occurring in one spot?

Sometimes you need to insulate the roof deck.

exhaust fans and tapes are masking the real problem and expensive -- sealing and adding insulation will provide comfort and long term savings

 

[Jackfre]

My last northern winter was 2011 in MA. I had the worst ice dams in my 25 yrs there. Everyone in town was loosing roofs, gutters, walls, ceilings, and doing all kinds of things to cope with it. Yes, you are getting heat out of the house. Certainly try to prevent it paying particular attention to the eves/ceiling exterior wall area.

That said, That last year was really tough. We closed on the house on 2/28. I needed to solve the enormous ice problem before damage that would have screwed the deal. I pulled 100' of garden hose out and connected it to my tankless water heater. I shoveled the snow off the roof and used a spray nozzle with a shower type pattern. I ran hot water for 3 1/2 hours and by the end the roof looked like a summer day. The run off melted the ice off the driveway. Actually worked out as a pretty cool fix.

 

[Randy in Maine]

I don't get ice dams much. My garage is made of R-40 SIP panels including the ceiling. The roof is open to the outside air with both the soffit and a ridge vents.

My house has spray and rigid foam insulation with no soffit or ridge vents and doesn't get much even at the skylights.

 

[theoldwizard1]

I don't get ice dams much. My garage is made of R-40 SIP panels including the ceiling.

If I ever build another house, it will use SIPs !