Ice dam woes
Gents, I am an Electrical Engineer by profession. Your site is awesome, thanks... it is a shame that the home design and building industry can't incorporate this stuff so that homes are done right the first time around. Sorry... preaching to the choir.
We purchased a 2 year old home that we had inspected prior to purchase. The inspector either was ignorant of the issues in the attic or didn't look at all.
We started to suffer from ice dams in several locations after snowfall. West facing over porch and North facing garages. (Bonus rooms are over garages) For temporary relief I installed heat cable. After researching your site I decided to tackle the real problems myself. The home is located in Utah (6B zone). It has blown insulation to R38 in the flats and then what appears to be mainly R13-15 fiberglass batts on the vertical runs (knee walls and vaulted ceiling walls). Many places it was not fit right or installed correctly. Seems like there should be a better way to do vertical walls in attics.
Initial inspection of the attic revealed horrible sealing issues which I am remedying. All of the bathroom vents tubes(4x) were barley run to the soffit, which I am running out the side walls now. The plan is to get everything sealed up well and then add additional insulation + to meet zone recommendations.
Initial Blower door test revealed leakage area (ASTM 779) at 1.23 ft^2. For the size of home (5600sqft.) I plan to get this well below the target of 0.98 ft.^2.
My fear is that after all of this sealing and additional insulation, I will still not be able to overcome the sin of the air handler and duct work in the attic. :-( This should be outlawed in the codes!! So far I have totally enclosed and sealed the air handler itself as part of the conditioned space (closet). It was left wide open on the backside and top. (They just stuffed fiberglass batts around it)
I have sealed up the air handler supply duct metal work. From the supply coming out the top of the air handler, they have used flexible 7" (R8.0) duct that is black!! Would you suggest replacing the black with reflective? I know we will still be dealing with the flexible duct in the unconditioned space but moving it all in the conditioned space is not an option at this point without major renovation.
I did read on your site that the duct could be sealed with SPF. I was considering just burying what I can with blown insulation. We are in a very dry climate, would this still be an issue with condensation? Not sure what else to do to minimize radiant heat through the (R8.0) flex duct.
The other concern is the duct that runs the full length of the very small attic space above the bonus room. I am going to seal the duct and register but the radiant heat (and opposite in summer) is my real concern. Any suggestions? Maybe it is time to concede to increasing air flow.
See attached photo #1,2 (octopus monstrosity from air handler), #3 (flexible duct running above bonus room 2 sets of duct run east and west the entire length)
The floor of the bonus room over the garage has no insulation between floor joists, the openings at the knee wall are not sealed in any way and I can actually see the carpet poking through the edge. Photo #4. I am assuming I will either need to blow insulation down in between the joists and seal the ends. Any additional suggestions would be great. Maybe just SPF the whole thing?
Sorry. One last thing. The wind blows fierce from the east and drifts the snow up the roof to the turtle vents. Yeah go figure, they put the vents on the non-show side of the home. What happens is the snow blows in the vents and creates nice piles of snow that sit on the insulation until warmed and then we have leakage. I tried filter media which worked but it seemed to restrict the airflow too much. Any suggestions. I don't have adequate ventilation according to the S.F. of the attic.
Posted Mar 14, 2017 1:00 AM ET
Edited Mar 14, 2017 11:34 AM ET
Other Questions in GBA Pro help