There's snow on the roof, who care's

[SandburRanch]

Those with snow remaining on the roof probably have a type of ice dam, very little is known about, and water is entering the walls of the structure. In this case on my house, the complete roof had a layer of water under an eighth inch layer of ice topped by a foot of snow. The water at the walls had head pressure ( about 6' ) from the building line to the ridge. As soon as the ice was broken from the eave to the building line in a 2inch wide area, the head pressure was relieved and water ceased dripping from the windows.

More insulation may lower your heating bill but it doesn't prevent ice dams and water entering the walls. But it will change when it occurs as the outdoor ambient temperature changes.

 

[Egon]

Those with snow remaining on the roof probably have a type of ice dam, very little is known about, and water is entering the walls of the structure. In this case on my house, the complete roof had a layer of water under an eighth inch layer of ice topped by a foot of snow. The water at the walls had head pressure ( about 6' ) from the building line to the ridge. As soon as the ice was broken from the eave to the building line in a 2inch wide area, the head pressure was relieved and water ceased dripping from the windows.

More insulation may lower your heating bill but it doesn't prevent ice dams and water entering the walls. But it will change when it occurs as the outdoor ambient temperature changes.

ice dams are usually associated with poor ventilation, vapour barrier and lack of insulation.

 

[SandburRanch]

ice dams are usually associated with poor ventilation, vapour barrier and lack of insulation.

What happens when air above 32°F enters the vent system and supposedly travels the under side of the sheathing to the ridge vent while that insulating snow is on top? There are many people that don't understand the last sentence I wrote.

 

[Looking4new]

My painted steel roof is laying on top of a truss roof system. I never worry about snow load, BUT I do take care to try and remove the snow from in front of the wood stove chimnies. I have a super long roof rake.

 

[Ehanson]

I would not go up on my roof, pretty sure the shingles take a beating? If in the spring the ice near the eve got too thick, I would lay a heat tape along the edge and help it melt.
Speaking of that, I have to reshingle this year, 22 years and the sun/weather has destroyed them.

 

[ArlyA]

We do receive snow in the area we reside averaging 230". Most people here have snow removed from there roofs, twice a winter. Yes many people do have steel roofs which have there own set of problems. Removing snow loads helps whatever you covered it with, last longer. I work with bridges here which are designed for 100psf of snow weight. Yes, you read that right...

 

[nybirdman]

Lot of weight there with that much snow.When I lived in Central NY several people died with the snow covered their exhaust from the furnace.

 

[Egon]

What happens when air above 32°F enters the vent system and supposedly travels the under side of the sheathing to the ridge vent while that insulating snow is on top? There are many people that don't understand the last sentence I wrote.

If it's just ambient air circulating the roof will be the same temperature.

 

[Snobdds]

What happens when air above 32°F enters the vent system and supposedly travels the under side of the sheathing to the ridge vent while that insulating snow is on top? There are many people that don't understand the last sentence I wrote.

If the house is insulated properly...Nothing. The roof should be a cold roof in your example. Conditioned space should always be surrounded by insulation. If conditioned air is being allowed to come into contact with a roof, ice dams occur.

There is a science to insulating a house. Its amazing how many suppose it contractors have no idea on how to properly insulate a house.

 

[SandburRanch]

View attachment 499125

If it's just ambient air circulating the roof will be the same temperature.

With living area heat loss, bath vent ducts through the roof, sewer pipe venting that's above freezing, dryer venting duct in the attic, outdoor air above 32F entering the soffit and directed along the sheathing, keeping the attic below freezing is a lot of wishful thinking.

I'll be providing an escape route for the liquid hidden under the snow and ice and everyone else can do whatever they deem necessary to keep water and potential mold out of their walls.