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Water seeping from weep holes in vinyl siding?

Post in 'DIY and General non-hearth advice' started by trailrated, Jan 24, 2013.

  1. trailrated

    trailrated Member

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    I've been noticing some water drips from weep holes in the siding. I've seen it with no rain and have seen it with recent rain, but wouldn't think the water would have stuck around that long.

    Under what conditions would water seeping be normal? Its extremely cold right now and I had a small stream that dripped over 5 or 6 runs of shingles and froze. Some weep holes just have a single water drop just waiting to drip.

    Where is the water coming from? its making me nervous

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  2. woodgeek

    woodgeek Minister of Fire

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    Hard to speculate, but I would answer the conditions that you are experiencing right now. Last week was warm, so lets assume your conditioned air, furnishings, framing etc were in equilibrium with a fairly high amount of water vapor (i.e. your indoor humidity was something reasonable...say 30-50%). This week its COLD, and the outside temp is well below the dewpoint of your internal air. If you have air exfiltrating from your house, it could hit the back of the siding, condense, and run out the weep holes. That is why they're there.

    If your house is typical, you could have a couple quarts of water in the air, and many gallons in your furnishing and wood framing. Under current conditions, that water is leaving quickly, maybe 3-5 gallons a day, and you are spying a few drips. No worries.

    BTW, the siding is not supposed to be water proof. Your water protection comes from the stuff under the vinyl...tar paper or tyvek, that sheds any liquid water away from your wallboard and framing. The vinyl protects that stuff, looks a lot better, and is designed to breathe and weep and evaporate any water stuck behind it. Main reason 'insulated siding' is an oxymoron.
  3. semipro

    semipro Minister of Fire

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    woodgeek hit it.
    I would only add that its "by design" and working properly if water vapor is coming through the house wrap and then condensing on the back of the vinyl.
    If however, air is leaking through holes in the house wrap or gaps around penetrations and then condensing on the inside of the siding then that's a problem. Those sorts of air leaks shouldn't exist.
  4. woodgeek

    woodgeek Minister of Fire

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    indeed. I wouldn't lose sleep over it, but the drip locations prob correspond to seams in your housewrap, or seams aligned with interior walls, that provide exfiltration paths. Hard to say whether they are big or small. Most air leakage is through the rim joist (inward in winter) and attic floor chases and top plates (outward in winter).
  5. trailrated

    trailrated Member

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    Your last sentence is concerning. Finding out for sure would be tricky I'm assuming. I know the weep holes are there for a reason, I'm just trying to find out if I have a hidden problem. I checked other exterior wall areas of the house and didn't see anything. But I need to keep checking
  6. semipro

    semipro Minister of Fire

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    I wouldn't be too concerned. All houses leak air some. I'd be less concerned if the leakage you saw was somewhat uniformly distributed across the side of your building. That would tend to indicate uniform water vapor leakage through the house wrap as expected.
  7. Hogwildz

    Hogwildz Minister of Fire

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    If there is snow/ice on your roof, there is also the possibility of ice damning at the gutter, assuming you have gutters, they may be full of ice, and during ice melt during the day from roof into gutter, the runoff tends to run behind the gutter, and I have seen where it will run down the fascia board, even behind metal fascia capping, and then run down the wall behind the siding. Even if you have soffit, it could still run along the top of the soffit towards the wall and down behind the siding. All depends on if these things are present, and if they were installed corrects, or not.
    Otherwise, I agree it could also be condensation of the house air leaking out to the cold somewhere behind.

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