Expert: Michael J. Owen - 11/1/2009

Question
We moved to Northern New York about 1 1/2 years ago.  We bought a house built in 1969, but with a new (~3 yrs) roof. We had terrible problems with ice dams last winter, as I noticed most houses in our neighborhood did.  I went into the attic and determined we need to blow in some more insulation (currently about 5-6 inches worth up there).  But I also noticed the house has no soffit vents or ridge  vents, but only a single gable vent at either end of the house. As the house is "L" shaped, one vent faces roughly east and the other roughly south. I am not excited about installing a ridge vent, but would like to add soffit vents if you think they would help. If so, what is the best way ensure they stay clear in the attic and don't get covered in insulation?

Answer
Hi Steve. Just happened to be online this morning. Sounds like you could use some more insulation. I think the minimum is around 10". Adding soffit vents should not be a problem as this can be done from outside. (You would have to evaluate this yourself or a carpenter could). The trick is to put up barriers so that the additional insulation does not block the vents. Polystyrene or cardboard types are readily available but fitting them is difficult.
The gable vents may be sufficient to vent the attic but the rule of thumb is one square foot of venting for every 150 sq/ft of attic area. A ridge vent is by far a better bet and not too difficult to install after the fact.
Here is a web site that should help you better understand your options:

http://www.rd.com/18231/article18231.html

Hope this helps.