Problem with Attic Moisture

[pnott63]

I have been experiencing some moisture in my attic this year and would like to get some advice on how to solve the problem.

What's in my attic:

- The attic has a continuos ridge vent with continuos soffet vent along both eaves. The vents seem to be working and there is no insulation blocking the soffet vents.

- The attic floor is well insulated with R30 insulation w/ an attach vapor barrier facing the attic floor.

- My drop-down attic stairs has a battic door w/ insulation so there shouldn't be any heat leak though the opening.

- The bathroom fan is vented through the soffet vent and no air is escaping in the attic

- There is a gas hot air furnace in the attic which had some leaking duct work. The leaks have been fixed and some additional insulation has be added to the ducts.

I thought by fixing the leaks in the ducts, my problem would be solved, but the North side of the roof still has some moisture. It is a two story house located in eastern MA. The house does not have a lot of humidity (usually around 30 - 45%). and the attic is definitely cold. It has been a rather damp winter in the Northeast, maybe that has something to do with the problem.

The only options that I can think of are:

1. Add an additional vent where the furnace is located just in case there is some small heat leaks that I missed. (If I do this, I'm worried that this would affect the airflow for the ridge vent)
2. Install an Attic Fan w/ an Adjustable Thermostat and Humidistat with the idea that the humidistat would detect moisture build and vent it out. Any suggestions on what the humidistat should be set at (I'm thinking 45 - 55%)

Please let me know if anyone has any suggestions on something else to check in the attic, or what you think of my options and which one would work the best.

thanks in advance

[Sev]

Moisture must be coming from somewhere- either furnace or interior of house(I'm assuming no leaks from outside). If furnace, check for leaks again. No blockages in exhaust ducting/ chimney? If from inside of house, you would probably see darkened areas on ceiling of 2nd floor, condensation from where warm, moist air encounters gap in attic floor insulation. Moisture is definitely inside attic, yes? North side of roof could certainly show signs of moisture(eg lichen/ mildew) on outside- put zinc strips under shingles for this.

[trader4]

"The attic floor is well insulated with R30 insulation w/ an attach vapor barrier facing the attic floor. "

Facing the attic floor or facing the ceiling of the living space below? The vapor barrier should be against the ceiling of the living space.

[pnott63]

thanks for the reply...

There is no signs of moisture on the second floor ceiling. I'll check the furance again, the only thought that I have here is that there is a grate around the steel chimney for the furance that was tar'd over this summer due to rain leaking in. I didn't think it would make that much of a difference given that I have a ridge vent.

The north side of the roof looks ok, no signs of mildew. There is some black along the soffet vent on the north side, maybe the moisture is coming in from here. It has been a very warm and rainy winter.

[pnott63]

The vapor barirer is facing the attic floor...thanks

snipped-for-privacy@> "The attic floor is well insulated with R30 insulation w/ an attach

[barry]

Living in SW CT, I can tell you that your RH is too high, IMHO. Keeping humidistat @ 25%, windows in some unheated rooms just start to show condensation. (double-pane, low-e, of course.)

With that RH, small leaks into attic from room(s) below could easily cause your problem. Poorly taped drywall joint, minor gaps here and there, and the mold is off and growing. Previous owner of my house had one small series of gaps in ceiling, maybe totaling 1 sq inch- provided growth media for various green and black flora. (And ... for a list of reasons, their impact on the inside RH was purely random.) Even on inside of roof deck, you could see evidence of condensation, on most of roof.

HTH, J

[m Ransley]

To get mold alot of air is leaking, a blower door test apx 300 will identify alot of your issues except furnace which still likely leaks. R

30 is probably under code for your area and definatly not optimal,R 60 may be fo you area-zone. Air can leak in outlets, foam insulation covers are cheap, up through walls from the basement etc. You may be under ventilated there are vent size per sq ft recommendations you need to research, a power vent will just pull out heated air. Your attic door may not seal, there are alltypes of sizes available, A blower door test woul eliminate most everything.

[pnott63]

Thanks for the Replies....

I don't believe that the RH level in my house is the issue, there is no condensation on any of the windows. Also, I open the second floor windows each morning to let the humid air out from running the humidifers in the bedroom at night. I'll check for any gaps but really haven't notice any in the past seven years.

A blower door test sounds like a good idea. The Attic Door has a tight fit and there is an insulated cover over it and all my outlets have foam cover.