Roof with no soffit venting
I recently posted a question about roof deck insulation materials and soffit baffles. I have a another question relating to the topic but thought it’d be best to post a separate discussion. Look for the first discussion link at the bottom.
Climate zone 5
When measuring the distance between the rafters to cut the soffit baffles I noticed the eaves aren’t vented. The home has 2 gable vents, north and south facing. The roof is an older roof with no ridge venting. The attic shows no signs of mold or rotting. My question is, if the home is over 70 years old and shows no signs of mold, should we continue to leave the soffits un-vented?
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Many older houses with a lot of air-leaks and very little insulation do not see mold or rot because the heat loss keeps the roof structure warm and dry. The problems come when you add insulation to the attic floor leaving the roof above much colder. As you are planning to add insulation I would definitely add soffit venting - and also make sure the gable-vents provide enough vented area.
The easiest way to retrofit soffit vents is probably to use something like these: https://www.rona.ca/en/round-soffit-vent-4-white-8497073?viewStore=61740&cm_mmc=shopping_google-_-1697454928-_-69158655114-_-pla-850152119004&gclid=EAIaIQobChMIrrnuoba65QIVCB6tBh018AQwEAQYASABEgJk4fD_BwE
Yes, we're preparing to replace the old-weathered insulation with new insulation, and doubling the amount which was previously there. It looks like they offer similar products in the US. Do you think 1 is required between every set of rafters?
Only if you need that many to make up the required air volume. Another fairly easy solution is to remove a board every so often and replace it with perforated stock as I did on this house:
I didn't realize you already had insulation in the attic. I'm going to walk back on my recommendations for venting. Given you have had no moisture problems, I would be inclined to add the new insulation and hold off venting the soffits. Monitor things for a year and see if they are necessary.