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Cape houses - insulation & ventilation

I live in a cape in Syracuse, NY. I'm having some work done and have received a nbr. of estimates on insulating my house. Some have suggested that I don't need to insulate the sides of the house that it's the roof that needs insulation. Some have suggested using cellulose spray in and others are suggesting foam (I suppose I would have to remove the ceiling sheetrock to have the foam). I now realize how difficult it is to insulate and ventilate a cape.

My problem is that in the winter I have icicles from the edge of the roof to the ground. I have forced air heat and I do have a heat vent in the attic. But I've been told by my contractor that I have no ventilation and the soffits are solid (no air vents) with no place for air to circulate. The warm area in the roof causes snow to melt which then forms large icicles.

I have been researching for a solution and came upon a company that uses a "Cool Vent" system. It is an insulation product with a layer of polyiso insulation, a middle layer of wood spacers with a 1-2" airspace and a top layer of OSB/plywood. It also features cross directional airflow. My head is spinning with all this information.

Do you have any suggestions? I am looking for the most efficient way to resolve this problem. And yes, money is an issue.

Asked by Denyce Lott
Posted Jun 11, 2014 1:35 PM ET
Edited Jun 11, 2014 2:16 PM ET


2 Answers

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First of all, you wrote, "I do have a heat vent in the attic." That's strange, unless your attic is a finished room.

You are correct that it can be difficult to insulate the top floor of a Cape Cod house. The best solution is to install a continuous layer (or multiple layers) of rigid foam insulation on top of your roof sheathing, followed by new roof sheathing and new roofing. You can combine the rigid foam and the roof sheathing in one step if you install structural insulated panels (SIPs) or nailbase. (The Cool-Vent product from Hunter Panels, which you mention, is a brand of nailbase.)

If you do this work, you have to make sure that you have properly air sealed the perimeter of your roof, and that the air barrier on your walls is continuous with the air barrier on your roof assembly.

Ideally, the layers of rigid foam that you install on top of your existing roof sheathing will provide at least the minimum R-value required by your local building code. In many areas of the country, that means at least R-38 of foam.

The work will not be cheap. For more information, see:

How to Build an Insulated Cathedral Ceiling

Prevent Ice Dams With Air Sealing and Insulation

Two ways to insulate attic kneewalls

Answered by Martin Holladay
Posted Jun 11, 2014 2:12 PM ET


Maybe having an energy audit would be a good start.
What sort of condition is the house in generally? Is it old and in tough shape or?

Answered by stephen sheehy
Posted Jun 11, 2014 2:19 PM ET

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