Ventilation questions for 1.5 story
I have an old 50’s style cape cod 1.5 story with kneewalls, slants etc in cold climate in Minneapolis ….I have over the last 10 years upgraded the insulation gone through 2 blower door tests etc. Yet I still get more ice damming than I feel is unacceptable. One thing that has not been thoroughly investigated is whether the ventilation is adequate and more importantly that it is balanced (intake vs. exhaust). I have the opportunity to change this as I’m getting a new roof.
At present I have a few soffit vents cut in. A wall louver on the siding behind the knewalls but only one side of the house So you have you no cross ventilation with the wall louver vents. I guess the logic was intake @ sofit vent exhaust to wall louver?
The slants which travel from the top of knewalls to the ridge area are blown full. They had the original encased rockwool insulation and then were blown full with cellouse insulation. This was all done in a retrofit insulation project.
The slants are are the week point as they are only framed with this only 2×4’s so you don’t have enough depth for proper insulation.
Above the ceiling where the slants transition to the ridge area I have gable vents on both sides of the house West and East sides.
I guess the current configuration is somewhat irrelvant. I guess my pointed question is what is the proper way to ventilate when you have
1) Knee walls
2) Slants (that are blown full of insulation) no chance for baffles to be inserted to ridge. This separates the area behind the kneewalls and the ride area as no air is able travel to the ridge area
3) Gable vents both sides above ceiling in the ridge area ( I assume this is fine as this achieves cross ventilation as gables vents are on present on the East and West side of the house
4) Wall louvers behind knee walls but ONLY on one side of house.
5) A few sofit vents cut in on the back and front of the house
I have read about Smartvent from DCI but makes me nervous with the potential in a severe ice damming situation that it would back up and have nice cavity simply to come through, if it were to back up on the roof. Perhaps these are not a good idea in cold climates due to this potential?
Any suggestions? I think Martin earlier in his career was a roofer?