Or, just sealing the attic with spray foam insullation. Stops the stack effect.
Hope this helps;
You need to take a good energy energy auditing and/or building science course!!!
You’re right of course, I don’t know what I was thinking. Actually I do. I was thinking about those times in the 70’s when water would run right out of the walls because builders had completely sealed the home (on the outside) with plastic. We had to demo the walls and remove the plastic but the recommendation was to leave the poly in the attic yet slice it with a knife here and there from the attic side.
I stand corrected!
These house designers, code officials and builders should have taken the recommended courses also!!!
I was in on the beginning of our R2000 (highly efficient sealed home with HRV) program in the 1980-90’s. I was a site advisor/blower door tester/inspector in my local area as well as troubleshooter for the whole provincial program for New Brunswick. I did 1 research contract visiting the homes to check ventilation systems, technical design “as built” details and homeowner impressions/concerns, if any, after 6+ months of living in the home.
One of the biggest problems was that these homes were running too dry in the coldest parts of the winter…they were way over ventilated. There was no history to look to when setting ventilation rates for an airtight house so the rate they chose was higher than ASHRAE rates for apartment buildings at the time. The required ventilation rates have now been reduced 3 or 4 times in the approx 25 years that the program has run.
Other problems were the noise of some of the ventilation systems as they were being designed and built in small start-up backyard businesses (Broan, Lennox, York, Trane, etc weren’t interested with the systems then) so the best engineering/design practices and motors were not being incorporated. Other problems were similar to all new technologies that are introduced into an environment…there is a learning curve of how to do it best and efficiently- poor location of ventilation grilles, poor duct sealing, etc.
All the above houses were very airtight **AND **did not have the problems you mentioned…all R2000 builders were trained and certified how to do it right and had to do updates every few years to keep their certs. There were a bunch of builders that did not take the courses but copied the the sirsealing techniques R2000 used. They did not put in full house ventilation systems but only code specified sickly $15 bathroom fans…these houses became major mould incubators!!! Every one blamed the airtightness/R2000 and not the untrained, stupid builders who really did not know what they were doing but would not pay for the training to save their own asses.
“Common sense is not all that common, is it!!!”
I would like to point out; the MacNeish - Rollins perspective is across two continents with huge climate zone differences between them.
Nashville Tennessee homes have a whole lot more moisture (grains/lb. not relative humidity) to deal with in winter months than in Canada. I have lived and built houses in both climate zones and they have a separate set of circumstances to consider and deal with.
Let’s share our experiences, and not get in heated debate over which practices better over the other because it’s like comparing apples and oranges.
On another thread, Peter in New Hampshire and Kevin in New Jersey have a different view on soffet ventilation. The mere distance between New Hampshire and New Jersey can make all the difference in the world. New England is a very diversified area that covers a small geographical area and what can work in New Hampshire, may not work even in New Jersey.
I could never leave my house on a motorcycle in New Hampshire without a winter jacket but rode my motorcycle at Fort Dix New Jersey much of the winter (except for the winter of 1972)! As Peter has shown us, Mount Washington New Hampshire has the most hostile weather anywhere in the lower 48 states.
Actually in NH we move moisture laden air by mechanical means to the exterior of the home. Along with air sealing you must get that moisture from kitchen and baths out of the house.
If you have moisture in the attic, it got there by air movement, therefore, in my area, you have not installed the insulation correctly or you may have other air sealing issue’s
Good Point David. By the way, I originally come from Freedom, New Hampshire in the Mt. Washington Valley. The Mount holds the record for the highest windspeed ever recorded on earth… I believe it is 232 mph. Tuckerman’s ravine on the mount has recieved over 200 feet of snow in a winter. They ski into August there. I’d say that’s in the running for most hostile weather in the entire United States.
-47F is not the lowest temp in the lower 48, but add 231mph and you have one heck of a wind chill! 
Today we are going to have high temperatures in the mid 20s with 15-20 mph winds.
Good recipe for wind washing in a drafty home.