You have insulation layer snow cold air space vent then the insulated roof deck.
Snow insulation roof.
In fact having a reasonable depth layer of snow on a roof is a good thing as long as the roof is designed to handle the weight.
Nailbase must be vented in high snow load areas.
A layer of snow insulates your house from above preventing the heat from escaping and thus significantly lowering your electricity bill.
It does help with ice dams though.
It is a sign that the roof is adequately insulated and vented.
And more importantly where should you store all of it.
Of course that amount of snow on a flat roof that s not built for it is going to cause all kinds of other headaches.
Without the insulation properties of snow the inuit could never have survived in the harsh arctic wilderness.
A house that has a bare roof when all the others in the area are covered in snow or has excessive ice formation is a sure sign of poor insulation and inadequate.
It also provides an additional level of insulation and protects the roofing material from sun exposure which is your roof s worst enemy.
But on average snow has an r value of 1 per inch about the same as wood.
Insulating in and around your roof attic space also prevents long term damage from moisture build up or ice damming which results from the warm air trying to escape through the apex of the roof but instead heating up the snow.
Install roofing underlayment flashing and cladding as per best practices.
In extreme snow regions it is typical to add a vented air space between the roof cladding shingles and the rigid insulation in figure 7 to flush heat away trapped due to the insulating value of the snow the snow becomes an insulating blanket.
Snow accumulating in decent amounts on your roof without melting in certain unusual spots is a testimony that your attic is doing its job meaning there s no heat loss through the roof due to poor insulation.
Many homeowners report that their homes feel warmer after a good snow as long as there s enough insulation in the attic floor to keep that heat inside and the snow on the roof.
In essence creating a vented unvented hybrid roof assembly.
Where you really see the amazing insulation properties of snow in action is in the igloo.
Rigid insulation layers exterior to existing roof sheathing must provide sufficient thermal insulation r value to control condensation risk see climate specific guidance.
If you re shoveling a tad too much you can damage the roofing tiles.
Its r value varies depending on moisture content and density of the snow granules.
A properly insulated home doesn t show bare patches of melted snow on the roof.
Install nailbase for cladding.
Twelve inches of snow have roughly the same insulating value as a 2x4 wall filled with fiberglass insulation.
Snow is an insulator.
Who would have the energy to spend each morning meticulously shoveling the snow off the roof.