Doc Holm,

You’ve helped many people in the past with their problems.  My problem is running rampant in my neighborhood.  I should’ve written earlier but I didn’t think of it until I heard we are supposed to have a colder and snowier weather than normal.  Our home was built in the ’60’s and it’s a typical colonial.  I HAVE ICE DAMS IN THE WINTER.  I don’t want to repair and repaint again.  Can you look at my house for me and tell me what you see and what I should do?  Maybe you can than write about my scenario to your readers.

Love your columns.

Rob H.

Northville, MI

Readers, followers, hanger-oners-

I haven’t made house calls in years but I thought this case study would be beneficial for Doc H to leave the comfort of his space, venture outside and report to the general public (that’s you guys) his observations… here is the findings:


Some observations regarding your main 2nd story attic space.  The square footage is approximately 1,248 square feet.

1- for exhaust ventilation, GAF/Elk (shingle manufacture) and Lomanco (ventilation manufacture) as well as code requirements, on a 1,600 square foot attic, 22 linear feet of ridge vent (396 sq. inches) is required.  You have approximately 36 linear feet, generating approximately 648 square inches of net free air exhausting your attic.  That exceeds exhaust ventilation requirements.
2- for intake ventilation, at the minimum, a balanced venting system is required, meaning, square inches of intake air should equal at least the square inches of exhausting air (as long as minimum requirements are met).  You have, excluding the intake vent over the bathroom window, (11) intake louvered vents rated at 65 square inches of net free air per vent generating 715 square inches of net free air.  The intake air amount exceeds the exhaust air amount and that is a very good relationship.
Summary on ventilation:  the existing intake and exhaust ventilation exceeds the minimum requirements.

Additional observations in attic space;
1- I noticed (3) non-insulated tubes for bathroom fans and/or dryers in the attic, exhausting directly into the attic space without dedicated vents.  A dedicated exhaust vent would be similar to the small black vent on the rear of your house by the chimney.  Non-insulated tubing is a unnecessary and unwanted source of heat in the winter time.
2- There is a whole house fan in the attic with no cover.  You mentioned to me in the winter time when there is snow on your roof, that is one of the first areas the snow melts, indicating more warm air is entering your attic unnecessarily.
3- I noticed (2) relatively new looking power exhaust vents on the roof top.  When these are operating, they draw air from the closest source which would be the ridge vent.  Drawing fresh air from the ridge vent would not facilitate the use of existing intake vents and pulling fresh air from the bottom edges of your attic to the peak and making your attic “cooler.”
4- Insulation: Code requirement for insulation in the attic, in new home construction  is R-49.  Presently the majority (over 80%) of your attic is blanketed with 6″ fiberglass rolled insulation which when brand new represents a R-19 value.  Again, with this limited insulation value this is an unnecessary and unwanted source of heat in the winter time.

I know this is a ton of info to digest. It appears to me there are simple fixes to ease the ice dam problem without having to move to Florida.  Have insulated duct work installed for bath and dryer vents.  Proper exhausting through the roof of bathrooms and dryers, use the existing intake air and get rid of the power vents, and add insulation.  Don’t forget- the FEDERAL TAX Credit is still available until the end of this year.  But the insulation has to be installed this year!

doc h