I’m building a new home in northern Michigan. It’s an A frame design with a second floor. The main (great room) is the A frame area. I’ve completed the insulation in the whole house. R-38 between the rafters in the A frame. R-19 in the outside walls and the attic area has R-19 between the trusses and R-30 on top of that. I have the heat system up and running, it’s a Carrier 2 stage forced air system. Last week we had 8 inches of snow fall. The next day I had about a 2 foot length of ice build up on both A frame roof edge soffets on each side of the house. They were both in the same area 180 degrees apart. It was not sunny and these both face east and west.
I checked inside the house where the R-38 goes into the soffet area and it seems like its in deep enough and done correctly. I also just started the ceiling finish which is tongue and groove pine and only done half way up the east side ceiling.
Any idead why I’m getting the snow melt on the soffet edge?
Flyinbye2
Replies
We don't get much snow / ice in TX, but when I built in Tennessee the snow would melt inside the exteior wall and above the Attic, run down to the soffit and refreeze. We called it ice damming.
If the roof was installed in fall / winter without much hot weather and the shingles did not have a chance to seal properly, the snow continued to melt above Attic, it would run down and hit the ice dam and in the worst case scenario it would run inside the home. We had this happen one time.
Now cold climate builders use water and ice shield around the perimeter to prevent water inside the home.
I am not sure if this is what is happening in your case....not
Air leaks? Duct work? Open framing cavities leading into the roof?
Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein (or maybe Mark Twain)
"Get off your dead #### and on your dying feet." Mom
"Everything not forbidden is compulsory." T.H. White, The Book of Merlin
Please tell us you are using an air barrier behind the T&G.
FG and I don't get along, I'm a cellulose and foam guy myself.
Pictures might help us figure this out.
Welcome to Northern Michigan.
Garett
You're not clear as to where precisely the ice is. Is it on the roof, hanging off the roof edge, inside the soffit, or where?
I build in N.Mich. see this problem quite often.
1. soffit is closed at wall and rafter connection
2. blocking installed and has no way for air to pass ie: drill holes in blocking
3 no air gap along rafter and roof sheating
4 air leak somewhere
Live and Learn: Although This is the first house( and the last) I have (will) build on my own I discovered the problem over the weekend.
The R-38 that is between the rafters comes down to the soffet area above the top plate. However it does not extend down slightly into the soffet to block the air exchange. So I am getting some air (Warm) under the edge of the insulation into the soffet and warming the roof.
My fix: and please tell me if you disagree. I removed the last length of insulation between the rafters. I took a piece of Luan that fit between the rafters and was long enough to be nailed to the top plate and extend out to the baffel. After that I put some insulation into the V groove that was formed to stop any additional air from getteing into the soffet. The baffel is still in place for air to cool the roof.
I replaced the R-38 between the rafters, which extends down to the top plate and also is in contact with the additional insulation in the V groove.
Now all I need is another 8" of snow to see if this was the fix.
Flyinbye2
Or find someone with a thermal imaging camera. Lucky you found the small gap in the batts at the ends of the rafter bay before you finished the ceiling. I think the larger issue of air infiltration though the T&G should be considered. If it were my house, I'd be installing an inch or two of rigid foam between the rafters and the T&G, taped and sealed, to increase the R-value of the ceiling as well as limit air movement into the rafter bays.
Sounds like you found your problem. Generally I will let the insulation extend over top plate this can be done in various fashion.
1) clean and dirty cut back insulation at a angle that follows roof pitch, so air flow is not impeded
2) purchase baffles at lumber or big box that staples to roof and extends into soffit.
3) apply cleats to side of rafters and then apply rigid foam or luan as you have done.
It sounds as that you have applied luan to top plate, therefore eliminating any insulation at wall and ceiling intersection. This type of fix will give you a cold spot at this area.