Foam Bangor - Sealing the Attic Envelope
New England Spray Foam New Technology Building Science
Spray Foam Insulation in the Attic Floor (Non-Vented Attic Spaces)

In this application, considered the most effective, by most of the SPF industry, the foam is sprayed directly to the underside of the roof between the joists, down around the rim and into the soffit areas, on the gable wall ends, and effectively sealing off and insulating the entire attic space from any air infiltration.

By now you have probably heard of this procedure with terms like: "Hot Roof design", Unvented Attic, Conditioned Attic, or "The Insulated Envelope." We at New England Spray Foam use the term "Unvented Attic."
Click here to view the ICC Unvented Roof Complaince in PDF format. Click here to view the ICC Unvented Roof Complaince in PDF format.
Preventing Ice Dams
Inadequate Attic Insulation Causes Ice Dams. Ice dams occur when snow melts on sloped roofs and then refreezes again. They are most often caused by attics and roofs with inadequate insulation. Two circumstances combine to make an ice dam.

If your home does not have proper and effective attic insulation, heat can escape from the living space during the cold winter months. Heat is transferred from the living space and also generated from recessed light fixtures, air ducts, furnaces and other appliances and equipment located in the attic. This heat raises the roof temperature above the freezing point, causing the snow and ice on the roof to melt and flow downward.

This area is often just inside the perimeter of the outside walls. Once the melted snow, or water, meets back up with the colder part of the roof (overhang) that hangs over and outside of the interior walls (just above the soffit vent area), it begins to freeze again, expand and back up. This dam that forms is where this effect gets its name from; ice dam.

Have you ever noticed one house that is completely covered with snow on the roof? Then you see a house with no snow, or with areas that have completely melted away. Contrary to one's belief, the house with all the snow on its roof, typically resembles the better insulated one. You may also notice huge, long icicles hanging down off the roof of one house, but not on another. These are all signs of an inadequately insulated roof and/or attic space.

Damage Can Occur

Backed up water can get under the shingles and through the roof deck. It can drip on the ceiling insulation or run down the underside of the deck to the connection between the roof and the walls. It then makes its way into the building in the form of damaging leaks. It can also lead to mold and mildew.

Melt water under the unmelted snow can decrease the friction between the snow and the roof and cause a dangerous snow slide, like an avalanche. Melt water often refreezes as icicles hanging from the gutters or edge of the roof. These icicles eventually break off when they get too heavy. Both snow slides and falling icicles endanger passersby.
Conduction, Convection and Radiant Heat Transfer
Foam Bangor - Insulating the Attic Envelope - Standard In a standard insulation system, ceiling insulation reduces the transfer of heat from the attic to the living space (in the summer). Attic temperatures can often approach 140°F during the day. Most of this heat enters the attic space through a multi-step process.

First, solar energy warms the shingles and sheathing. The hot sheathing then transfers heat to the rest of the attic through conduction, convection and radiant heat transfer. The 140°F temperature of the underside roof surface drives the heat transfer process.

Foam Bangor - Insulating the Attic Envelope - Unvented Attic System




By having New England Spray Foam insulate the roof surface with spray foam, the surface temperature exposed to the attic (the temperature driving the heat transfer) is reduced by as much as 40°F.

Both conduction and convection heat transfer are proportional to a temperature difference, so that heat transfer will be reduced proportional to the drop in surface temperature.


The benefits of including the attic in the insulated space are:
New England Spray Foam Research PDF's
Learning the Difference between Open Cell and Closed Cell Spray Foam. Click here to view the Learning the Difference between Open Cell and Closed Cell Spray Foam in PDF format.

Spray-in-Place Polyurethane Foam Insulation Engineering Report. Click here to view the Spray-in-Place Polyurethane Foam Insulation Engineering Report in PDF format.