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Community and Q&A

I have water coming in the house in spring, coming through the drywall and light fixtures

user-6727875 | Posted in General Questions on

I have metal roofing on 1×4 strapping, R-40 insulation, vapor barrier, then 5/8-inch drywall. This is all new in the last 3 years.

Can you help me, please? It’s like no one here knows what’s going on. And I have put a lot of money out.

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  1. GBA Editor
    Martin Holladay | | #1

    It's impossible to say for sure what's going on without a site visit, but I have a pretty good guess.

    If these drips occur on days when there is no rain, it's probably not a roof leak. It's probably condensation.

    During the spring, metal roofing gets cold at night (due to a phenomenon called nighttime radiation cooling). The roofing radiates its heat to the cold night sky, especially on clear nights. By morning, the roofing temperature can be colder than the air temperature.

    Later in the morning, the day gets warmer. Pretty soon some warm, humid outdoor air enters the roof assembly between the 1x4 strapping. This warm outdoor air contacts the underside of the cold metal roofing. Moisture condenses on the cold metal, and drips through your insulation, wetting your ceiling.

    Most roofers understand this phenomenon, and they won't install metal roofing on 1x4 strapping unless it's on a barn. For a house, you need solid roof sheathing (usually plywood or OSB) protected by roofing underlayment (usually asphalt felt). This roofing underlayment catches the condensation. The moisture drips on the underlayment, and is either directed to the eaves or allowed to evaporate.

    So your roof was built wrong. If the vapor barrier you're talking about is polyethylene, that's also a bad idea.

    Solving the problem won't be cheap. You'll probably need to remove the metal roofing, install solid roof sheathing like OSB or plywood, install roofing underlayment, and then reinstall the metal roofing.

    Who did the work? Roofing underlayment is required by building codes, so your roofer or builder appears to have violated building code requirements.

  2. user-6727875 | | #2

    My roof was inspected. It was done to prints and was passed by inspiration. It only leaks for 3 or 4 days, then it doesn't leak anymore. I live up north in the YT in Whitehorse, where there is not much humidity.

  3. GBA Editor
    Martin Holladay | | #3

    "My roof was inspected." Are you talking about a code official or a home inspector hired to evaluate a house before the house is sold? Code officials often miss code violations (and they cannot be sued if they do miss code violations), and home inspectors make mistakes every day.

    "My roof was done to prints." Then the person who prepared the blueprints made a mistake.

    "It only leaks for 3 or 4 days, and then it doesn't leak any more." That certainly sounds like condensation.

    "I live up north in the Yukon Territory in Whitehorse." That makes sense. The problem you describe is more common in cold climates than in warm climates.

  4. user-6727875 | | #4

    We bought a old house. We built a new one around it, from footings to the finish.

    So you're telling me, with blueprints and inspected and carpenter all supposed to be knowing what they're doing, I'm supposed to think that they did it wrong? And I should rip off the roof and start again? I'm not a carpenter.

  5. GBA Editor
    Martin Holladay | | #5

    If you're not a carpenter, then you certainly shouldn't rip off the roof.

    You have two choices: either live with the drips, or hire a contractor to fix the roof. If you hire a contractor, I recommend that you ask the contractor to read the information on this Q&A thread.

  6. user-6727875 | | #6

    You dont understand we built a new house around old and tor out old house we youes all contract carpenter electricians plumers drywallers and flooring i think you have miss read what im saying
    All i would like to now is how the roof should be done the right way so i can say something to the roofers that come its is very expensive and not all people that get house built- are contracters

  7. GBA Editor
    Martin Holladay | | #7

    I think I understand.

    The right way to build the roof is with solid roof sheathing (OSB or plywood) rather than just 1x4 strapping. The roof also needs a layer of roofing underlayment (for example, asphalt felt) between the OSB or plywood and the metal roofing.

    You're right that it will be expensive to fix this roof.

  8. user-6727875 | | #8

    It has aphalt under it know but with straping and what you're saying is to code here in Whitehorse right because im going to see inspector to day

  9. GBA Editor
    Martin Holladay | | #9

    If there is a layer of asphalt felt under your roofing, you may be experiencing another problem. You may have air leaks from the interior of your house that allow warm, humid interior air to contact the cold underside of the asphalt felt. If that's the case, you'll still have condensation and drips.

    The solution to this problem (if that's what is happening) is to perform air sealing work at the ceiling level.

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