Attic insulation question.

[jslo]

Ideally you want R 30 insulation in attic, baffles to keep an air gap between insulation and roof deck at soffits and soffit vents and adequate gable or roof vents to allow good air circulation.

[Sackett]

Ideally you want R 30 insulation in attic, baffles to keep an air gap between insulation and roof deck at soffits and soffit vents and adequate gable or roof vents to allow good air circulation.

Current code requires R-38 in the attic plus, more is better. Remember, the attic insulation is not to keep your attic warm, it is to keep your house warm. "Lack" of insulation in your attic should have no bearing on ice formation in your gutters, as your attic is going to be not too much warmer than the outside. I would be curious to know if your soffit vents are blocked or if your roof jacks (or ridge vent) are clogged. Don't know why, but inadequate airflow is tickling the back of my brain.

[def90]

"Lack" of insulation in your attic should have no bearing on ice formation in your gutters, as your attic is going to be not too much warmer than the outside.

Yes it does to a point, it's a combination of insulation and ventilation. lack of insulation allows the heat to escape into the attic thus heating the roof, even with poor ventilation if you have good insulation you shouldn't have a problem. The snow on the roof melts and trickles down until it gets to the eave which is now cooler than the heated roof due to a lack of a heat source underneath it and then refreezes creating an ice dam. Proper ventilation will help prevent this as heat is allowed to escape through the roof vents and cooler air is drawn in through the soffit vents. Either way, the proper way to prevent/fix ice daming is to make sure your attic is properly insulated as well as properly ventilated, they go hand in hand. Also, don't forget to seal all of the openings in the top plates of all the walls before putting in the insulation.