Replacement

I have a home in Minnesota where there are ice dams building up and causing leaking inside. I want to fix the issue and not just put a band aid on it but I'm not sure how. Everywhere I have read says that there is not enough ventilation in the areas where the dams are forming. The problem I have is that the home is a 1.5 story and the 2nd floor is finished, but there are dormers (Crawl space between the bedroom wall and roof) surrounding the perimeter of the house (for the most part). The people who owned the home before me installed blown in insulation between the roofing and the bottom of the roof 2x4's (so basically 3 1/2" of insulation) and put cardboard up to keep the insulation in place.

With the way they did this there is no air movement because the edge of the roof is packed with insulation. This is where I'm stuck on what to do to get ventilation through there. I don't want to completely open it up permanently because there is a bedroom and a den up there and I need it to stay warm.

Any ideas on how to get that area ventilated without loosing heat in the rest of the living area?

Wuzzat?

Here's what I did but I never got a chance to test it because we never had a repeat of that flukey winter several years ago where everyone here at 39N had ice dams.

We had a t'stat-operated gable attic fan for ventilation in summer to reduce the A/C bill. No temp. difference between roof underside and ambient air = no ice dam, so I ran a switch w/pilot light bypassing the 'stat so I could run the fan in winter.

You have to have a well insulated attic floor to preserve the comfort of those below, and if you have that you don't really need an attic fan in the summer.

Replacement

The attic is a livable area, there is a bedroom and den up there.
Plus the roof doesn't have an over hang at all.
I'll try to get some pics or a drawing.

travelover

Short term I'd get some electric cables up there to prevent water damage, than next spring I'd work on more ventilation and some membrane roof underlayment.

Wuzzat?

In view of post #3, I'd say do #4 and look here

Replacement

I started by googling Ice dam prevention and couldn't come across anything that was specific to my situation, then I came across this forum hoping I would find the answer here. I was going to do the heating cable idea also.

oldognewtrick

Replacement, 1st off welcome to House Repair Talk.

Can you get a digital camera and take some pics of the sofit and area in the crawl space. There are some solutions to your issues but if possible post a pic for us to see the area you are talking about.

Wuzzat?

That, or have a 3' wide or more membrane so the roof can hold water in the dam area.
Doesn't sound like too many options here.

Replacement

I'll try to get some. It is a rental property so it may be a few days...

gseyler

I had, from what you have discribed, the same problem earlier this winter. Dormers with insulation in the attic restricting airflow from soffit up through the roof vent? Yup same thing. I was able to go to the local home store and buy roof vents, ProVent rafter vents is what I bought. They were about 2 bucks a pop, made of black plastic. You place them in each bay created by the roof frames. Nail or staple them in place and bam you have a vent that will ensure the air from your soffits has a space to go up through the dormer. From what i remember most building codes require at least 1" of space.
I checked my roof in the crawlspace a few days after I instaled them and it was as dry as could be. I'm hoping for a much lower a/c bil this summer as well.
Hope this helped.