ice dams

[henkmeuzelaar]

I agree that a "cold roof" over an attic with good ventilation and a carefully insulated floor is in many ways the simplest and best solution, provided you religiously insulate any vent, flue, chimney or roof a/c ducting that traverses the space between attic floor and roof. In principle, this insulation should extend to well above the expected snow level in order to make sure no warm air, etc., can cause melting of the snow on top of the roof. In practice, that is rarely done, I believe. As a consequence, any snow that melts around these roof perforations (as you can see happening on roof tops all around you) will freeze out again somewhere on its way down; usually over the eaves. thus forming an ice dam.

This is probably one of the main reasons one finds relatively few newer houses with attics here in the high altitude Rocky Mountains areas. Instead, we mostly see cathedral roofs because of better space utilization, better daylight ingress and easier roof access for the various heating, cooling and other ducted devices of todays households.

Even in cathedral roofs, however, the "cold roof" principle is getting more popular nowadays, despite the very high cost of construction. Essentially, this requires the construction of two separate roofs with the inner roof heavily insulated (usually at the R39 or R50 level in our nick of the woods) and separated from the outer roof by a 1/2 to 1 foot high vented space.

Henk

 

[gfreek]

Gutters tend to increase the problem also....

 

[Dougsey]

Don- What is the copper pipe I see in your pic?

 

[wilburg]

What I did to atatch a Garden hose to my shower:

1) get an adapter for a handheld shower head (silver piece)
2) fit an adapter for a 3/4inch hose (brass piece)

I bought both pieces at home depot.

I mostly use this to wash my dogs with warm water outside of the house, but also works for my ice dams

(photo is sideways)

 

[peakbagger]

One overlooked cause of ice dams on homes with proper insulation and clear soffit vents is blocked ridge vents. Many new homes have ridge vents only with no gable end vents. The ridge vents work great until a big snow storm covers them over, then the attic warms up and its ice dam time until the vents are clear.

By the way, most newer roofs in snow areas are rated for 40 pounds per square foot live load. Once snow starts getting over 4' the roof is probably at or near design load. Very rarely does a roof fail slowly, usually it fails from a defect in the original construction and when they go, they usually go quickly.

 

[henkmeuzelaar]

One overlooked cause of ice dams on homes with proper insulation and clear soffit vents is blocked ridge vents. Many new homes have ridge vents only with no gable end vents. The ridge vents work great until a big snow storm covers them over, then the attic warms up and its ice dam time until the vents are clear.

By the way, most newer roofs in snow areas are rated for 40 pounds per square foot live load. Once snow starts getting over 4' the roof is probably at or near design load. Very rarely does a roof fail slowly, usually it fails from a defect in the original construction and when they go, they usually go quickly.

Our old Utah home, in Summit Park at 7,200 ft has 90 PSF roof snow load requirements and in nearby Park City the homes at 8,400 ft need to be constructed for no less than 160 PSF.

However, since we do have the occasional 300 - 400 inch snow year, we certainly have gotten up on the roof to shovel snow from vulnerable porch and other overhang sections, especially when the groaning timbers would start waking up my wife at night. When you are shoveling down a 6ft, highly compacted snow layer you can occasionally feel the roof rise under your feet, like when you are boarding an airplane just when the automatic load leveling kicks in....

Henk

 

[SmokeyTheBear]

The only time I take a snow rake to the roof here is when the depth on the roof exceeds 48" or is wet due to heavy wet snow. It is a matter of weight and nothing but weight.

I have only used the snow rake twice, both times it was our first winter here. I also had to clear off the deck 2 times that winter. No way to rake the roof on one side without clearing the deck at least once.

We had a snow ball fight in the back yard (or is it the front yard, oh well) on May 5 that first spring.

Yes, but only if your insulation is good enough.

If it is poor enough that you have continuous slow melting near the higher parts in combination with re-freezing over the eaves (particularly during extended day/night thaw/freeze cycles you have a recipe for giant ice dam formation.

In the latter case it is probably wise to immediately remove all the snow after each storm, as some of the posters appear to be doing.

Henkl

The insulation I have is good enough, no ice dams. No valleys. Vents are all free, Old hand at dealing with ice dams and other roof issues so I just watch the snow load, one thing when it is the fluffy stuff, entirely different matter if it is the wet stuff. If I move the snow off of the rear (or is it the front) deck when it gets 3' high I have to move 32 cubic yards of it. Pain in the back, arms, and other anatomical parts of this geezer.

My wife has been picking away at the deck since it looks like the roof is going to need raking this year.

 

[Don2222]

Don- What is the copper pipe I see in your pic?

That pipe is the vent pipe for the bathroom sink. Copper was cheap back in 1962 when the house was built. LOL

 

[SmokeyTheBear]

Don- What is the copper pipe I see in your pic?

That pipe is the vent pipe for the bathroom sink. Copper was cheap back in 1962 when the house was built. LOL

Told ya, not to post pictures like that, too many of us geezers can still see ;-).

 

[Don2222]

Don- What is the copper pipe I see in your pic?

That pipe is the vent pipe for the bathroom sink. Copper was cheap back in 1962 when the house was built. LOL

Told ya, not to post pictures like that, too many of us geezers can still see ;-).

Ok Smokey I just cropped it out.

 

[peakbagger]

for folks in NH, here is a study on recomended ground snow loads by town.
http://www.senh.org/committee reports/tr02-6.pdf
A roof should be built to withstand these loads, unfortunately in the rural towns where the loads get quite high, the towns dont have building inspectors and therefore even though folks are supposed to build to a high snow load, they usually dont.

 

[Xena]

I had a small leak coming in my bedroom this morning.
The drip woke me up @ 6 am. Went out there when it
got light out and raked another foot back from the edges
of the roof around the entire house, and the leak stopped shortly after even though
there is a few inches of ice there and the gutters are filled
to the brim with ice.
We have good insulation, soffit vents and a ridge vent
but my brother painted the house this year and was lazy
and painted over the soffit vents so they are blocked.
He's been away for the weekend but when he gets home
he will be getting his ass up on a ladder to rake the snow
that I couldn't reach from the ground. More white stuff
coming tomorrow. Oy.

 

[nh1234]

Been reading all of this great stuff about ice dams..cause and effect stuff. While proper construction can minimize the problem it is not always possible to revise mistakes made in original construction. Two years ago I had BIG problems with ice dams and then of course water damage. Did a LOT of researching and a lot of possible resolutions do not work. Finally found a resolution
while it is NOT cheap it will resolve the issue. Go to the folling link and check it out (broken link removed to http://www.bylinusa.com/roof_ice_melt/RIM.html)

 

[henkmeuzelaar]

Been reading all of this great stuff about ice dams..cause and effect stuff. While proper construction can minimize the problem it is not always possible to revise mistakes made in original construction. Two years ago I had BIG problems with ice dams and then of course water damage. Did a LOT of researching and a lot of possible resolutions do not work. Finally found a resolution
while it is NOT cheap it will resolve the issue. Go to the folling link and check it out (broken link removed to http://www.bylinusa.com/roof_ice_melt/RIM.html)

Yeah, that looks like a technically satisfying technology.

Although installation is probably quite costly if you don't already have a proper aluminum roof skirt installed I think there are a number of ways DIY installers can achieve safe and effective results; e.g. by burying a heat cable under an existing skirt (so it does not get damaged by the ice and does not just form ice tunnels/caves but spreads the heat out over a much larger area.

The biggest problem are the monthly operating costs. At 36 W/ft power consumption, let's say over a 100 ft long roof edge, we are talking 3.6 kW
If you need to run this for an entire month you could use up more than 2600 kWh. In many areas this could set you back 300 to 500 dollar per month, just for keeping the ice from the roof.

I know that with proper control and regulation, you could probably reduce that by a factor 2 or 3 in milder climates or winters, Yet, when I see numbers like that (added onto the installation cost) I would rather spend my money on trying to achieve a properly insulated roof.

Henk

 

[nh1234]

I totally agree about the possible cost of installation AND I am NOT happy about the ongoing cost to run the damned things..BUT I was less thrilled about the water damage and cost associated with that. I installed it myself (not difficult) and it seems to be working great..will NOT be happy to get the electric bill BUT and very happy right now that I do not have water running into the house. If it were at all possible I would have chosen trying to fix things with proper ventilation. Just thought I would let people know what is out there.. Last poster did a great job of reviewing the product and discovered the pitfalls very quickly.

 

[SmokeyTheBear]

One overlooked cause of ice dams on homes with proper insulation and clear soffit vents is blocked ridge vents. Many new homes have ridge vents only with no gable end vents. The ridge vents work great until a big snow storm covers them over, then the attic warms up and its ice dam time until the vents are clear.

By the way, most newer roofs in snow areas are rated for 40 pounds per square foot live load. Once snow starts getting over 4' the roof is probably at or near design load. Very rarely does a roof fail slowly, usually it fails from a defect in the original construction and when they go, they usually go quickly.

For what it is worth 70 lbs per square foot is code where I am.

 

[slls]

I rake roof every storm, no ice dams, it's why I rake.

what do you use to rake the roof?

Home made, 25 ft long aluminum 1 inch tubing, 2 aluminum licence plates attached on the end.
Rake a story and half house. Tubing was from a huge TV antenna given to me. I believe it's the only one in captivity.
I only rake one side of the house, where the sun hits most, melts then freezes at the eves, other side doesn't bother.

 

[SmokeyTheBear]

I rake roof every storm, no ice dams, it's why I rake.

what do you use to rake the roof?

One of these: http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias=aps&field-keywords=Roof+Rake&x=0&y=0

 

[henkmeuzelaar]

I rake roof every storm, no ice dams, it's why I rake.

what do you use to rake the roof?

Home made, 25 ft long aluminum 1 inch tubing, 2 aluminum licence plates attached on the end.
Rake a story and half house. Tubing was from a huge TV antenna given to me. I believe it's the only one in captivity.
I only rake one side of the house, where the sun hits most, melts then freezes at the eves, other side doesn't bother.

Ah, great Idea!

We just switched Utah license plates for Idaho ones (hope my wife did not yet throw them away....).

Henk

 

[Czech]

Two things really quick, not sure if mentioned. Rather than adapt your shower head, what's wrong with the clothes washer hook up or water heater drain to connect a hose? Both are most likely male hose thread. For soffet vents, a leaf blower from the outside in during the nicer months assures that your blown in insulation is not covering the vent.

 

[Shortstuff]

Here's just a peek at what I tried to get off my roof today. Just to the left of the chimney there's a valley that actually had a measured 40" of snow in it which is now gone. I'll be sore tomorrow.

 

[jumpink]

Thanks Smokey. All the retailers are sold out on the rakes, looks like I have to get creative and improvise.

I have huge ice dams all around the entire house. I thought it was because I never cleaned out the gutters in the fall but reading this post makes me think it is more like an insulation issue.

 

[Kevin Willis]

Here's just a peek at what I tried to get off my roof today. Just to the left of the chimney there's a valley that actually had a measured 40" of snow in it which is now gone. I'll be sore tomorrow.

That is some nasty looking ice, It must be one well built house. I have never seen ice like that except at the lodge snow skiing or something. wow

 

[Don2222]

Hello

Any ideas on this?

I have good insulation but I still have a premature melt line from the sofit all the way up to the ridge right where the Vent pipe is??
It makes more icicles on the overhang outside the bathroom window and drives me nuts

So what do I do to prevent this?

Pic 1 & 3 shows issue

Pic 2 shows aluminum foil coated foam board I screwed into the 2 rafters where the vent is from the sofit to the ridge as a possible fix??

 

[Shortstuff]

Don2222 it looks like that is a PVC pipe. It wouldn't hurt to add another foot or two with a coupler would it?