Moisture Problem

[JIM MURPHY]

Not sure how to address this question. I did an inspection yesterday that had considerable mold problems at all of the registers in the second story ceiling and in bathroom ceilings. I am thinking that there is a ventilation problem with the attic. The attic was insulated, had soffit, ridge vents and gable end vents. The roof decking had an Owens Corning foiled sheathing that must of had plywood over it or it was very thick since none of the roofing nails penetrated the interior of it. The house was built in the 70s. The bathrooms were vented with exhaust fans and exterior windows. Just thinking the house was wrapped too tight. Any ideas????

Jim Murphy

[Jerry Peck]

Jim,

The photos at the supply registers indicate that there is air leakage where the ceiling supply boot mounts to the ceiling between it and the register itself. Cold air leaking out there will absolutely cause what your photos show.

The photo with the round spot next to the supply register is likely also leaking where the duct is attached to the boot (at least that's what I've always heard them called and called them, probably 'ceiling supply box' is a better term). When that leaks cold air there will be condensation, which will drip as shown, additionally, blowing cold air down to the ceiling will cause condensation on the ceiling.

The other two photos, one looks like around a bathroom exhaust fan and the other a recessed light fixture, looks like peeling paint, which, if in a bathroom, could be caused by many things, including: not using bathroom exhaust fan, exhaust fan not working, exhaust fan inadequate for long hot steam generating showers, exhaust fan working properly and dumping all the exhausted air onto the top side of the ceiling, many things could cause that.

[archivoyeur]

Two thoughts come to mind right away:
1)- Are the bathrooms vented to the outside directly, or vented into the attic?
We see this in this part of the country, (commonly in 70's era housing), when the house is vented into the attic. The main purpose of passive ventilation with ridge and soffit vents is to condition the roof. Moist air will have a hard time finding its own way out of the attic. Be sure the home is not vented into the attic.

2) The ridge and soffit vents work together to create an air pressure effect similar to a chimney, (Bernoulli effect). When the wind blows across the ridge vent, lower pressure at the top draws air up through the soffits, along the underside of the roof.

a-Where is the attic insulation? If it is on the attic floor you will need baffles at the pinch points to push the insulation back, and allow air to flow in from the eaves. If the insulation is between the rafters up under the roof deck, you will need continuous baffling up to the ridge vent, to allow the air to flow and condition the roof.

b- Because the ridge and soffit vents work in tandem, and dependent on the difference in air pressures between the top and bottom of the roof, adding a gable vent trashes the system. Like a straw with a hole in the side. A roof system should have ridge/soffit venting, OR gable venting, not both. And ridge/soffit allows more of the roof to be conditioned than gable venting, which relies on cross ventilation, and can leave large 'dead' spots

[Scott Patterson]

I agree with Jerry, it is more of an air duct/register leakage issue. It is also common to see stains around a register that has been closed off at the register and not with a damper in the duct. The metal register becomes so cold that water condensates and you can end up with what you see in the pictures.

The bathroom, I would just have to chuck it up to not enough ventilation or the vent fan was never used during shower time.

[Billy Stephens]

I agree with Jerry, it is more of an air duct/register leakage issue.
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The AC System ( A coil blockage, Improper charge, ) could contribute to this condition as well.
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[Thomas Kirchner]

I agree with the possibility of the A/C maybe having something to do with this.
Are the supply ducts insulated? Moisture may condense inside the ducting and be sent out the vents. Likewise, colder winter air could cause condensation during the heating season.
Perhaps that foil on the underside of the roof decking is helping to contain moisture or heat in the attic space.
Also, is the ratio of venting appropriate for the area of the attic?

[Mike Schulz]

Jerry nailed it. Everyone I have seen like that was caused by the register boot not insulated properly.

[Jerry McCarthy]

I suspect it's a combination of what Jerry P stated and the roof decking with an Owens Corning foil wrap. Classic case of over-sealing, which was explained to me by Joe Lstiburek during a CREIA conference in 2002.

[Michael Chambers]

A couple of other possibilities. With the supply registers, a combination of uninsulated supply ducts in the attic and a humidifier being turned up way too high causing condensation inside the ductwork during colder weather. With the bathroom exhausts, I'm agreeing more with their not being adequate or not being used when needed - possibly in conjunction with not enough insulation in the attic, but I've also seen several instances of more localized damage to the ceiling right around these units from uninsulated metal exhaust tubing being run through an attic during colder weather, and the moisture in the hot damp air condensing on the cold metal tubing interior, and running back down the inside.

[Evan Grugett]

Good responses all. I am curoius if the home had a separate (hydronic) heating system from the air system? If so, with open registers in winter, the heat from the space would enter the cold duct system in the attic and condense. I have seen this a few times and always recommend to the client in the report that the supply registers be closed and the return grill sealed for the winter (the filter in the return grill can be wrapped with something to prevent or reduce air leakage.

[Scott Patterson]

Good responses all. I am curoius if the home had a separate (hydronic) heating system from the air system? If so, with open registers in winter, the heat from the space would enter the cold duct system in the attic and condense. I have seen this a few times and always recommend to the client in the report that the supply registers be closed and the return grill sealed for the winter (the filter in the return grill can be wrapped with something to prevent or reduce air leakage.

With Jim's location in South Carolina, hydronic heat will not be an issue.

[Mike Schulz]

We still have allot of hydronic systems in N. Carolina Inspected two of those systems last week. Both where from the mid 90's

[Caoimhín P. Connell]

For what it's worth - I'm on board with Jerry.

Thermal bridging, resulting in condensation.

Although I see one small colony of mould, I don't see a mould problem, possibly not included in the photos.

CaoimhÃ*n

[Mike Schulz]

Homes I have seen like this are from the 50's and 60's. Little insulation, High gloss paint on the ceiling (less permeable) and vent-less gas wall heaters. No fans in the bathroom only windows that never opened. Wet crawl space and Mom boiling everything on the stove. Place is like a rain forest.

[Mike Schulz]

:confused: Why are all my replies stuck on 632?