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ejager

Unusual spotting on new home stucco.

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Good Sunday morning to you all!

I was asked to take a look at a new house, owner occupied for just over a year, where there was significant water and frost forming in closet, along a wall above the joist space that contains the fresh air intake for the HVAC, and in an outisde corner.

The relative humidity in Alberta at this time of year is rarely much above 60%, but since the air temperature is below freezing, the humidity levels inside homes where the exhauset fans are used regularly, is quite low.Its customary to talk about using a humidifier in the winter for heating efficiencies. In this 2000 ft sq. home (plus developed basement), with only an older couple living in it, the dehumidifier is drawing out at least 1.5 gallons per day.

Using my moisture meter, I detected a few square feet of the oak flooring in each of the three locations was 4-5% higher than the baseline of 15% tested in the center of the rooms, and in the hallways. The walls were drywall and exhibited no moisture higher than 12" above the floor or more than two feet from the locations the home said had frost. On the day I came the temperature outside was a few degrees above freezing, not like the continued 20-25 degrees C below zero we had been experiencing for the last few weeks.

One location was 12" past the vertical edge of the a window, but there was no further interior evidence of leaking.

The attic was quite dry. Though the combustion air intake for the furnace was iced up beneath the cellulose insulation (which was damp and obviously indicative of a problem that needs to be remedied before nearby trusses suffer from prolonged moisture exposure). No overt signs of leaking, no ice dams, vented soffit with cardboard ballfles, no roof top vents to allow snow in, though the gable ends do have vented soffits. There is fiberglass batting between top of gable wall and bottom of roof deck at the bottom 4-6 feet of slope of the gable walls presumably to stop/inhibit the short-circuiting of ventilation.

Outside was more interesting.

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These pics are from the north side of the house, though there were a few similar spots on the south side, adjacent to the front door where attached garage joined the house, protected by a 6' overhang (front porch)

Any guesses what the stucco spotting is from?

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No accessory/expansion beads below the window; how about above? Stucco goes right up to that window frame? Looks like it's aluminum. Is it? Is that window underneath an overhanging eave or is it exposed to the wind/rain/weather? How is the top of that window detailed?

ONE TEAM - ONE FIGHT!!!

Mike

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Window frames, about 8" from overhanging eaves

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What is the technical explanation for how the nail heads effect this type of discolouration?

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. . . What is the technical explanation for how the nail heads effect this type of discolouration?

Hell, I don't have any idea. The spots just look like they're telegraphing the nailheads.

Thermal bridging?

Rust?

- Jim Katen, Oregon

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Hell, I don't have any idea. The spots just look like they're telegraphing the nailheads.

Thermal bridging?

Rust?

- Jim Katen, Oregon

- You seemed so certain with your answer I thought you had an unrefutable explanation for the same thoughts I had but could not prove or explain through (in)experience.[:-slaphap

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I thought it was nailheads too; but not due to thermal bridging. The stucco job doesn't look right at all to me. My guess is that he used substandard fasteners, the fasteners are corroding and the rust is starting to come through the portland cement.

ONE TEAM - ONE FIGHT!!!

Mike

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About the only sure fire way to tell what is going on is to cut open a section of the wall. As Jim noted, it looks like the fasteners/nails are telegraphing through the stucco. Several reasons can cause this and the most common would be an improper thickness of the stucco and the wrong type of fasteners.

It also sounds like the house has an insulation problem if they have frost in a closet!

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About the only sure fire way to tell what is going on is to cut open a section of the wall. As Jim noted, it looks like the fasteners/nails are telegraphing through the stucco. Several reasons can cause this and the most common would be an improper thickness of the stucco and the wrong type of fasteners.

It also sounds like the house has an insulation problem if they have frost in a closet!

sounds like a job for a .... HOLMES INSPECTION!!!! probably not sensational enough though [:-thumbd]

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