Attic insulation question.

[buffalobo]

Just get rid of the gutters, no more ice damns.

[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.

[Wulf202]

Lack of insulation causes heat to get dumped in the attic causing the roof to get warm and melt the snow which then runs down to the gutters which are un heated and then the water will freeze before it gets to the down spout assuming the ambient temperature is cold enough.

Lack of airflow alone will cause cold spots. You can actually see the overstuffed stud cavities the day after a light snow on alot of the old a framed houses.

No matter how much insulation you have the attic should be about the same as the ambient. The insulation blocks the heat transfer from the attic to the living space.

[Sackett]

Well said, Def. I knew that ventilation had a part but didn't put together the lack of insulation. Building science...always learning.

[Wulf202]

Ninja'd by def.

[OtterbatHellcat]

Thanks guys....

I did get my ass all up in the attic today, and I DO have like 8 inch baffle insulation layed all out through the affected area, AND i noticed its not really laid down all that well. SEEMS to me that I really do have too much heat escaping from the home heating process up into the attic space. The attic designed heating/ cooling ducts ARE and ARE not fully insulated as I would think they should be. Ancillary sheet metal does have insulation surrounding the arteries, but the main trunk has nothing on it at all??

Do I need to insulate the main trunk? I would think so.

Would it be prudent to go ahead and dump a butt ton of that fluffy insulation stuff all over the stuff that is already there?

[Wulf202]

First make sure the ducts seams are sealed with tape or liquid duct sealant. The main trunk may be insulated on the inside.

Its going to be alot easier to throw some batts down than do blown in. If you're going to do blown in just add several inches to the whole place.

Blue sky will sell batts 20% or so cheaper than depot

[OtterbatHellcat]

Thanks Wulf.

[Wulf202]

bluesealsam@gmail.com

Correction blue seal not sky.

I might have some r38 craft batts left over this summer