Water dripping from felt in the loft (condensation?)

Discussion in 'Builders' Talk' started by JamieFarmer, Jan 26, 2023.

  1. JamieFarmer

    JamieFarmer Member

    IMG_1561.jpg IMG_1562.jpg IMG_1563.jpg IMG_1564.jpg I've noticed the north facing side of my house roof has water dripping from the insulation/roof felt in the loft. House was built pre-1970 and doesn't appear to have any vents in the roof, but in the loft there's gaps between some of the insulation on the inside of the rafters (see pictures). Is this normal and just a build up of condensation?
     
  2. Rail_man

    Rail_man Member

    I have the same problem. It's normal to an extent - i.e. given the colder weather we have had lately. I think it's because the warm air in the house is hitting the cold roof and condensing. This is particularly in issue if you have added insulation and have double glazing without trickle vents or with the vents closed.

    I have installed some felt vents which sit in the overlaps to get a bit of airflow. It has helped the worst area above the bathroom, but seems to have shifted the problem along!
     
    JamieFarmer likes this.
  3. Bob Rathbone

    Bob Rathbone Screwfix Select

    You have insulation with no vapour barrier to prevent the water vapour reaching the cold side of the insulation, this is a strange way to insulate a loft. To stop the condensation, fit a vapour barrier on the warm side of the insulation, ensure adequate ventilation above.
     
    JamieFarmer likes this.
  4. The Happy Builder

    The Happy Builder Screwfix Select

    Is that all the insulation you have or is there insulation all across the ceilings?
     
  5. JamieFarmer

    JamieFarmer Member

    There's insulation across the ceiling/floor of the loft as well.
     
  6. JamieFarmer

    JamieFarmer Member

    I've bought some felt/lap vents and will give them a try. Read that they need to installed on both sides of the roof and not opposite each other, so that the air can flow from one side to the other. Hopefully they help.
     

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