Attic condensation and mildew/mold and how to vent properly via gable venting

So we installed a new roof this summer and fall. We live in the Midwest with higher humidity. we went to do more renovations and noticed mold/mildew and condensation dripping off of the nails and the outer walls in between the wood. The decking is not showing any wetness, but the mold where it meets the rafters.

We have rafters with absolutely no soffits as there is no room to even add any. We originally had gables with gaps here and there as this house is very old. There was a Whirly bird vent that we did not reinstall. We added a ridge vent with the gables and left the bottom ridge open so air could come in.

We have since gotten more insulation, sealed up the lower edge leaks and any other nook or cranny where hot air from the house could possible get to the attic. A gable vent fan is getting put in as well with a humidifier so that it will turn on if the humidity gets too high.

We are also planning on getting rid of the ridge vent since we have read this has changed to the new intake nullifying the two gable vents.

Now, we have one room that is a dormer with absolutely no ventilation other than it’s own separate ridge vent aside from the main part with the gables. That’s all molded too.

The old roof was wood shake with decking on top and two more layers of shingle. Never had a problem and it only had gables.

Please help as the internet is no use… half say ridge vents work with gables and other things, the other half say they don’t. We want to save our roof and fix the problem. Thank you. !

We are also about to redo the roof on a separate lower roof for the house. It currently has no ventilation what so ever. Same thing, shake, decking , then two layers of shingle. We are planning to vault that one almost completely. Still no room for soffit vents. We don’t even have flashing.

install edge vent + leave ridge vent as it is ,like super easy,bottom cold air in -> top hotter air out .no stalling = no humid = no mold.

Cannot put edge vents on as listed in the post.
Looking to use the gables and improve the airflow.

You described it pretty well.
I think with outside pics we can be helpful.

We would like to use the gables as our rafters directly meet the roof joists with the decking laying flush against them. Yes there were cracks here and there as it’s and old house and not straight.

These will work. Make sure kitchen/bathroom fans are exhausted outside is critical.

Sadly no one has these in stock and it will take a long time for shipping and we really do not want to have to cut out a price of the decking. The exhaust fan has been sealed up for now until we can dry out the attic and give it it’s proper exhaust. The attic was at 75% humidity this morning, but half of the insulation has been removed to put new in. Which will happen today after the mold is cleaned up.

Do you have any tips for using the gable system versus the ridge vent and shingle vents? We are getting rid of the ridge vent as we had no issues prior to that being installed when roof was done.

Thank you.

The objective of ventilation is to remove heat and moisture from the attic. Gable end vents will work, but you have to have intake air to aid the convection of warm, moist air. This might be your problem…“sealed up the lower edge leaks and any other nook or cranny”

Blockquote we had the mold before we sealed up the nooks and crannies last night. Could you please clarify why you think it is that?

You’ve got a humidity gain in your attic from some source. If you’re taking showers, cooking, and breathing in the house with the windows closed, it will convect with heat and condense to a cold surface.

All the things that the other guy’s recommended is the proper way to do It,however I did see in your first pic that the paper side of your insulation was facing up that must be facing down toward your living area as this can cause these issues that you are experiencing