High Humidity in Attic Conversion
Hello, my (new to me) 1920s house has a third floor attic conversation bedroom that gets very humid–it rained last night and it was 67% this morning–so I’m looking to find ways to decrease the humidity. I’m currently using a dehumidifier and it’s not unusual for the 50 pint bucket to fill in one day. The attic above this bedroom contains the blower and ducts for the second and third floors’ a/c unit.
The roof is slate and the attic insulation, while I’m certainly no expert, doesn’t appear to be proper. There’s R-30 insulation inconsistently laid on top of the floor of the attic, along with some white fluffy material, partially inside and outside of red plastic, fitted into the floor (joists). There is no insulation on the ceiling of the attic (rafters), which I have researched a bit and can’t determine if problematic or proper due to the slate’s need to “breathe.” I believe there are no vents in the attic space.
The exterior walls of the room appear to be plaster on brick, as seen in the two places I’ve cut into the walls. We had a roof leak along the chimney for which we have had the chimney flashing repaired (along with various broken slate), though I can’t be sure the repair was proper until the walls dry out from the prior leak (which I’ve been told will take months due to the lack of breathing space given the plaster on brick), so I cut said holes in places where the plaster was “bubbling” and would need to be fixed anyway in attempt to possibly speed the drying process.
I’m curious whether the humidity issue is caused by the lack of wall insulation, the attic insulation, a combination, or something else, and how to fix the problem. I’m also curious whether I need to take any corrective steps for non-humidity reasons as well. Any guidance or suggestion would be greatly appreciated. Thanks in advance.
Photos (sort by oldest for more logical order): https://ibb.co/album/1v6DyQ
Note: I’m having the roofers come back to fix the few gaps in the ridge
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