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Condensation in attic

  • 07-12-2014 8:54pm
    #1
    Registered Users Posts: 7 ✭✭✭ scurly


    Hello,
    Went up to get the Xmas decorations today and noticed that there lots of condensation in my attic in half of the north facing part. Last winter I added another layer of insulation over one half of the north of the house (the same half that is now wet)

    The part with the best insulation has all the condensation. The other half has no condensation.

    Does anyone know if there is an issue with having better insulation in half of the attic? The vents do not seem blocked

    Thanks


Comments

  • Registered Users Posts: 267 ✭✭ Grudle


    scurly wrote: »
    Hello,
    Went up to get the Xmas decorations today and noticed that there lots of condensation in my attic in half of the north facing part. Last winter I added another layer of insulation over one half of the north of the house (the same half that is now wet)

    The part with the best insulation has all the condensation. The other half has no condensation.

    Does anyone know if there is an issue with having better insulation in half of the attic? The vents do not seem blocked

    Thanks

    Had the same issue with my attic when getting the decorations. In my case one of the venting hoses has come away from the roof so hot air was getting in that way.

    Tonights job is to empty the gathered water from the tube, patch a small hole with some duct tape and fix the hose back to the roof.

    Its worth checking that this hasn't happened in your attic.


  • Registered Users Posts: 7 ✭✭✭ scurly


    Thanks for the reply. Unfortunately that was not the problem - it would have been an easy fix so definitely worth checking first.


  • Moderators, Home & Garden Moderators Posts: 10,094 Mod ✭✭✭✭ BryanF


    How much moisture is levaing the heat envelope unregulated? The increased
    Insulation means there is colder air Above the insulation, that is probably not venting adequately


  • Registered Users Posts: 7 ✭✭✭ scurly


    About the amount of moisture: The affected area is about 5metres x 5metres.
    We are in a directly north-south facing house.
    All of the condensation is located in the north east corner of the house and gets worse the closer you get to the north east corner. Imagine a 2ft x 2ft square in that corner - there is enough condensation there to make water beads over that whole area, and then the further you get from that corner there are less and less beads, and then at about 5metres from that corner its dry.

    I had another look up there tonight. The area that I added a second layer of insulation is well vented. I can see right down to the soffits when I put my head close to the roof.

    Heres my plan: At the weekend I'll check for moss blocking any soffit vents, check the other areas for ventilation (the areas that I didnt add a second layer of insulation), and I'll see if I can get the next door neighbour to take a look at the same area in their house - maybe its nothing to do with the extra layer of insulation I put in.

    My best hope now is that the existing insulation over the other side of the house is blocking the ventilation a bit - that area is harder to get to but it would be an easy(ish) fix.

    Thanks for suggestions and comments.


  • Registered Users Posts: 5,970 ✭✭✭ alias no.9


    scurly wrote: »
    About the amount of moisture: The affected area is about 5metres x 5metres.
    We are in a directly north-south facing house.
    All of the condensation is located in the north east corner of the house and gets worse the closer you get to the north east corner. Imagine a 2ft x 2ft square in that corner - there is enough condensation there to make water beads over that whole area, and then the further you get from that corner there are less and less beads, and then at about 5metres from that corner its dry.

    I had another look up there tonight. The area that I added a second layer of insulation is well vented. I can see right down to the soffits when I put my head close to the roof.

    Heres my plan: At the weekend I'll check for moss blocking any soffit vents, check the other areas for ventilation (the areas that I didnt add a second layer of insulation), and I'll see if I can get the next door neighbour to take a look at the same area in their house - maybe its nothing to do with the extra layer of insulation I put in.

    My best hope now is that the existing insulation over the other side of the house is blocking the ventilation a bit - that area is harder to get to but it would be an easy(ish) fix.

    Thanks for suggestions and comments.

    What kind of heating have you? If you have an open fire / stove with back boiler, there should be an overflow tank in the attic. If your rads and hot water tank are not dissipating the heat from the boiler it could be going to the overflow tank hot, releasing vapour which is condensing on the cold surfaces.


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  • Registered Users Posts: 7,078 ✭✭✭ bladespin


    Noticed something similar last weekend while getting the Xmas decorations from the attic, we insulated 3-4 years back and have never had an issue, last weekend the plastic the bits were wrapped in felt particularly cold (it was a very cold day anyway) and felt slightly damp to touch, I was wondering if it was the weather (damp cold air circulating) or something more worrying.


  • Registered Users Posts: 1,046 ✭✭✭ gutteruu


    Do you have a frost protection heater in the attic? Might be the cause if too hot?


  • Registered Users Posts: 7 ✭✭✭ scurly


    I went back up to the attic yesterday morning at about 10am.
    The moisture was not nearly as bad as when I went up after work during the week - I was surprised by the difference. It must get worse as the day goes on.

    @alias no.9
    We have a closed system gas central heating. The pressure fill pipe/valve that allows you to pressurise the central heating from the tank was open. I closed it. Can hot water go backwards up to the tank? (About the open valve - I was told that people leave the valve open to keep the pressure up if there is a small leak in the central heating. Somebody else told me that its a bad idea to do that because it lets some oxygen in and then that can rust radiators.)

    @gutteruu
    I had never even heard of a frost protection heater until I read your comment. I didn't find one up there.

    Yesterday I got back up there and made sure all of the insulation was well away from the roof so air flow was not blocked. The airflow was not blocked - I pulled the insulation back about another 2 inches anyway. I can see the light all around the edge of the attic now (vented soffits all around edges).
    Im going to open the windows during the day for a bit too - there'd be plenty of days during the winter when they were not opened, so Im going to make it a definite during the day now.

    So I changed 3 things - heating valve closed, a few more inches clearance for insulation and open windows. I'll keep an eye on it - hopefully one of the days after work and maybe early next saturday too and I'll post an update.

    Now that I've been paying attention to roofs, ventilation, etc. I've noticed that all of the houses in the next neighbourhood have vented tiles in the roof. So if the problem is still there I'll get some of those in.

    Thanks for the help.


  • Registered Users Posts: 7 ✭✭✭ scurly


    Just a little update for anyone who is interested:

    After a few more observations on different types of weather it looks like my changes did absolutely nothing. The follow all make sense to me, I just though that the differences wouldn't be as big.
    Over the christmas we had:
    - a few very mild days (6 degrees) - there was absolutely no consensation.
    - cold with a bit of wind - no condensation either.
    - cold (minus 2 ish) with no wind - lots of condensation

    So in general the attic will be fine, but on the odd few cold calm days it will full of condensation.


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  • Registered Users Posts: 5,970 ✭✭✭ alias no.9


    scurly wrote: »
    Just a little update for anyone who is interested:

    After a few more observations on different types of weather it looks like my changes did absolutely nothing. The follow all make sense to me, I just though that the differences wouldn't be as big.
    Over the christmas we had:
    - a few very mild days (6 degrees) - there was absolutely no consensation.
    - cold with a bit of wind - no condensation either.
    - cold (minus 2 ish) with no wind - lots of condensation

    So in general the attic will be fine, but on the odd few cold calm days it will full of condensation.

    Sounds like there's damp air rising. On the cold windy days, there's enough of air moving to dissipate the moist air but on the cold calm days it's condensing.
    Is there an extraction fan in the kitchen or bathroom? Have you followed the ducting to see where it exhausts?


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