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Don't wait till you are on the ladder, get the Instal instructions online to map out exactly what you need to do
don't be like that guy who puts all the xmas tree lights together/ fixes the dead bulbs and finishes the instal with the plug next to the angel and his wife laughs at him
I wanked about with the thermostat ( 75$ )that gets plugged in between the heat cable & the 115V which you don't really need , I would just forgo it
Only 240W for your heat tape? That must be a short length (under 60’?). I think it’s somewhere around 5W/ft for a regular (constant output) line and 10W/ft with a self regulating line. So it can add up depending on how much tape you need.
I just try and clear the eves back a couple feet when there is more than a foot of snow built up on the roof, or when I see the ice start to form. Snow rake and a bit of arm power is cheaper than the tape. The ice melter in a stocking does work(slowly), but can rot your gutters.
I'm pretty sure that kit was 240W but fuck I don't remember what hapend last week
IME I needed more length than one would think because I had to zizgzag the roof to the end of the gutter which eats up bunch of length and then double back thru the gutters to the start so that is > than double the length of the roof
I don't do anything with the SE facing side of the roof cuz its not needed
in my case the snow constantly melts from roof mounted appliance vents and heat trace is the best way to completely mitigate my problem,
I could show you a picture of where the ice dam would be but a picture of nothing is pretty fucking boring
altho I havent tried the dynamite
Also, in the 'hold my beer & watch this department', you could use firearms! Just for grins, I used my pellet gun as a 'hammer drill' for a few shots. It'd take a LOT of pellets.:rolleyes2Quote:
Originally Posted by XXX-er
Every ice dam problem is actually an insulation problem, the saying goes.
fwiw
I would say design in a lot of cases
For me it’s always at the eve, where there is little to no insulation in the soffits. The rest of my attic is ceiling blown insulated style. Most of the melt comes from heat from vents, or sun and ambient temps that are just over zero (like what would happen at unfrozen ground level under the regular snowpack. Water runs down to the roof above the soffit and where it freezes. By removing the snow from that section of the eve the water has a chance to run off, or do a freeze and sublimate cycle that wouldn’t happen under the insulating roof snow.
At least that’s my story and I’m sticking to it. Seems to work so far, and while not Tahoe or Mammoth Lks snowpack, we often get snowpacks over a metre in our yard for extended periods, heavy years with 1.5m or a bit more.
We got 2.5’ at 2600’ in the Sierra foothills over 2days. Just above snow line. Rear locking diff on the land cruiser, 4lo, 2nd gear start and it was able to pack down a track in our several hundred-foot gravel driveway enough for our light awd Toyota Matrix to get out. Small skid steer loader and tractors owned by neighbors moved the snow on our private road. Older kid and I shoveled off our deck and paved areas. I finally shoveled to dirt a route to the covered wood piles. Currently cannot full extend by dominant arm at the elbow, which I think is a result of shoveling. Anybody know which muscle is doing that? Bicep, tricep, or something else?
I’ve seen a lot of peeps in the higher Sierra shoveling off their roofs because there’s a lot of water rolling in for the next 14 days. Friend with an older a-frame in bear valley can’t close any interior doors anymore and apparently there is not much to do or put the snow to relieve weight off their roof short of plowing the roads to their place (snowbound community) and bringing in a large excavator and dump truck, which is not realistic.
Yup, generally speaking it’s insufficient attic insulation. https://icedamremovalguys.com/what-c...-dam-can-form/Quote:
Originally Posted by ötzi
Heat tape is some sad ass shit. It’s like when a fat guy starts putting his belt above his gut.
I had the last few feet of shingles removed, and replaced with powder coat metal. Lots of newer homes or commercial bldgs in Tahoe and Mammoth have this. Tends to shed the snow naturally when sunny or temps increase. Sometimes if I’m traveling for a month I’ll come home to 8 ft drifts on the roof. But no ice dam issues.
Not 100% effective. Our neighbor has been in his house for 15 years, and his roof has metal edges. Never had ice dam issues before, but last week his ceiling in his bedroom collapsed.Quote:
Originally Posted by frorider
It seems the only way to fully eliminate ice damning without removing snow and ice from your roof 100% is to live underground. ;-) I suppose a flat roof designed to hold all of the potential snow in your area is an alternative, but will then in turn create other issues.
Cold roofs may work, but are reliant on simple roof designs and maintaining a reliable plenum for air flow from eave to a high point like ridge or shedded soffit over the insulated cavity to remove excess heat. A snow covered ridge vent, for instance, eliminates the air flow.
There are constantly changing variables from day to day, month to month, year to year, location to location, roof area to roof area, temperature to temperature, aspect to aspect, solar radiation to solar radiation, insulation to insulation, material to material, etc, etc. that come into play. Throw some rain, then freezing in the mix and it gets even more messed up.
Insulation resists thermal transfer. It does not eliminate it in conventional construction and certainly not in older structures or areas were there is very little insulation, like structural components at valleys or roof pitch transitions. Snow is also an insulator and also has mass. Where thermal equilibrium between the internal and external temperatures occurs is dependent on all kinds of variables.
Where water could freeze could be outside the roof or inside. It can happen on unheated porch roofs if the ambient temperature rises enough to melt snow on them from below.
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I know a guy who is a roofer and broke his back falling 10 feet. He drags himself around on crutches and still roofs without full mobility in his legs. He has people who work for him, but he still gets up on roofs and fastens shit down.Quote:
Originally Posted by Alpinord
What Alpinord says. Good design and execution handles 90% of it but the other 10% just happens. This is what I see at 8,000 feet in the Northern Mountains.
It shitty (generally older) construction, the heat from inside the home is transferred to the roof deck and melts the snow. Once the melt water gets outside the building envelope it freezes. This is usually on your eve and gable overhangs. It is usually worse on roofs that are not above attics (rafters and vaulted ceilings)
On new construction, it is usually shitty roof design. Around here the architects are under pressure from the client to deliver the pretty house. Some GCs really focus the conversation around "you don't want that" many don't. It this case it is usually were the roof pitch is exposed to the sun and then the melt water drains to a cold place like a valley or even a shady spot where one pitch shades another.
What seems to work is spray foam in the lid and 2 layers of Ice and Water Shield. This is expensive nerdy shit but it's the game we play.
So it appears all of you agree with the link I posted.
Here’s a more contractor-oriented link https://bct.eco.umass.edu/publicatio...ting-ice-dams/
Sealing out the warm air from getting into attic is key.
For decades my mom had a house at altitude in the CH alps. Hudge amounts of snow. Attics were cold AF. I don’t recall any houses in the village having any ice dam issues ever.
Yes you win the internet. It was a good summary by guys selling snow removal services but not the whole picture. A heat audit is not necessarily going to help everyone. But the line about removing snow can’t hurt and might help about everyone, except those who have nowhere else to put the snow.[emoji6]
Edit: regarding attics, you can power vent attics and for new construction provide a deeper ‘energy heel’ in the truss design to provide deeper insulation over the exterior walls while providing positive air flow from soffit vents. For older houses, the insulation gets compressed over the walls due to the heel depth of a 2x4 or a 2x6 with no air flow vs 14-16” or more. I’ll post some details later.
Parallel chord or scissor trusses can also be used vs TJI or dimensional lumber rafters to provide greater insulation and air flow over vaulted spaces. For heat in vaulted spaces, radiant floor (ideally with a mass) is more efficient than forced air because the heat source radiates warmth to you, vs heating the whole volume to feel comfortable, which in turn generates more heat at the ceilings.
EDIT 2: detail grab from library showing some typical roof conditions:
Attachment 450879
In my experience it's a combination of all the above factors with ventilation being more important than people realize. If we ever get stupid enough to build a place it's going to have a fucking single shed roof withstanding seam steel covering.
^^^^
IE no valleys. The Swiss & Bavarians figured it out a while ago. KISS!
As Foggy Goggles stated, the architects and designers are more pressured to do what they are told than what they know might work in suburban Phoenix, but not at 9,000 feet. I've had one client only over the years that insisted on 'NO VALLEYS ANYWHERE' and one let me fully loose to provide a very simple roof on a higher end home! The rest are Heinz 57 & complicated.
That's what we've got and made it through the winter with no icicle formation until ambient temps got enough above freezing to begin melting snow on our roof. The only thing I don't like is not having access to under the roof in case issues so show up.Quote:
Originally Posted by I Skied Bandini Mountain
We haven't had enough snow to worry about it this year but in years past we've had some issues in one small spot at the edge of an overhang which is directly above the back door (which is the main door we use) and the dryer vent. It's only a small spot but I think enough heat comes out of the house right there and gets under the overhang and melts shit just enough that a little water trickles down into the gutter, then freezes and backs shit up.
Even then it doesn't cause any problems until there's a warmer day and melt water wants to get in the gutter, can't because it's full of ice, so it overflows onto the landing right below and freezes there, which can be life threatening coming out the door if you're not paying attention.
I bought a little piece of heat tape for the spot but it's sitting on a shelf in the garage until next year. Salt and sand on the landing makes it manageable but gets tracked through the house and makes a mess.
Two a-frames at bear valley. These are not being used this winter. On a hillside. The one on the left is 3 stories. The bottom floor is a partial floor. I’m pretty sure they both have decks.
Attachment 450887
Any ice dams?Quote:
Originally Posted by bodywhomper
I don’t see any ice dams.
I have no realistic way to clear the upper roof. Local building code says house should have been designed for about 140# per square foot snow load, minimum, so just gonna have to hope it holds up. Guesstimating about 6-7' deep on the roof in the deepest parts - north facing valleys.
I pulled down some snow from the lower edges where I can reach from the ground, on the north side. The south, west, and east sides melted off a lot before the last 10 days of storms, so there's much less on those sides.
Warm storm in two days means rain at my elevation...
https://uploads.tapatalk-cdn.com/202...0f16a3c07e.jpg
I've posted a pic of this new construction house in my neighborhood before, but here it is again in all its poorly designed glory, with the right side roof terminating directly into the garage wall on the left. It's hard to see it now under all the snow. https://uploads.tapatalk-cdn.com/202...f55a685701.jpg