Ice Dam – how to vent?

[Dave]

Every winter I get an ice dam in the valley where two gables come together. /\/\ I’m planning on cutting open the kneewall to make sure there is airflow along the roof rafters – but there will not be any flow from the outside. How can I get the temperature in this crawlspace equal to the outside temperature? Should I add roof vents at this level?

/\
//\\
// \\ /\
// Vent //\\
//______\\ // <-- attic
// \\ //____\\
// \\ // \\
// \\ // \\
//| |\\####//| |\\
// | | \\##// | | \\
// | | \\// | | <---kneewall
//—————–[short ]————-\\
[gutter]
| |
| |

### – is where the water & ice form. Should I add roof vents here?

[Jay J]

Dave,

From your diagram, it seems to me that the only venting you have right now is at the gable-end(s). This is the ‘high point’ of the roof. So all you need is air to enter the attic from a ‘lower’ point in order to ‘push’ out any warm air that’s risen.

First, you need to do what you can to seal off the attic from the rest of the house. I’m going to assume you’ve got that under control. The only thing I would consider is putting in soffit vents on BOTH ENDS of your /\/\ Adding roof vents won’t help in ‘pushing’ any warm air out. And using inside air isn’t the answer either because all I can envision is warm air heating the ‘valley’ and the water freezing, thus, exacerbating your current problem.

So, from what I see, soffit vents on both ‘ends’ is the best solution. My best to ya and hope this helps. Hopefully, someone else will have a better / different answer.

Jay J

[TAEIK KIM]

The intent of the project is to provide protection for the personnel entering and exiting the building from falling icicles at a single door for our building project.

Our roof projects about 3 feet beyond the face of the building providing the perfect environment for the formation of icicles.

Someone in our office had researched the heat tracing on the roof and a guttering system. The solution became to expensive so I need your advice or comments regarding subject stated above.

We looked at placing a roof over the existing metal roof to create a “cold roof” – this option was much to expensive and never made it out of the office.

[Author]

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