What could be causing wet floor joists?

Discussion in 'Builders' Talk' started by rhenderson, Feb 20, 2023.

  1. rhenderson

    rhenderson New Member

    Hi folks,

    Since we took up some floorboards a few weeks ago, three of our joists have been wet.

    We had the heating on and they did seem to be drying but we've not had the heating on much the past fortnight and had a lot of rain and they are very wet again, as well as the floor underneath.

    There was a slab placed in front of the air brick at the patio door and we thought that was running water into the airbrick then the subfloor, but we removed the slab and the problem hasn't gone away. In fact, its actually got worse over the past week but that might be due to high rainfall.

    Interestingly, the ground doesn't seem as wet near the patio door as it does further into the room, but the ground to the left of the door where the wall is, is bone dry. We've only lifted a few boards so far so don't know if its widespread or is contained to just this section in front of the patio doors, but at the moment it does seem like just the stretch in front of the doors, even though the ground near the doors seems drier.

    The water also follows a weird pattern on the joists so we are really confused about where it's coming from, we wonder if it is coming up via the holes in the bricks under the joists.

    I'm not sure if the ground level outside is too high.

    I'll add some pictures and hopefully that gives enough info for some ideas


    Attached Files:

  2. rhenderson

    rhenderson New Member

    Sorry one more pic, what it looks like from outside the doors

    Attached Files:

  3. The Happy Builder

    The Happy Builder Screwfix Select

  4. Alan22

    Alan22 Screwfix Select

    I'm guessing the DPM under the door is letting in water and that was filling up in there, what you see now is it drained away.

    Then again that's all that is visible in the pic.
    rhenderson likes this.

    DBCDIY Screwfix Select

    Looks like the floor had a thick coating of bitumen? And the ground level outside looks too high...so you have an indoor pond!
    As for the joists could it be dripping condensation from the roof of your conservatory?
    rhenderson likes this.
  6. Can you get some polythene between the joists and a brick or 2 to see if it dries out? That should indicate if it is coming from below.
    rhenderson likes this.
  7. The Happy Builder

    The Happy Builder Screwfix Select

    I think is in Scotland, so possibly asphalt?
    DBCDIY likes this.
  8. rhenderson

    rhenderson New Member

    Ha, a big cat ;).

    It is Scotland.
  9. rhenderson

    rhenderson New Member

    Hmm yes the ground level does look high.

    I dont think anything dripping from the roof, as all the woodwork up there is dry.
    Thanks, yes the ground does look high. I wonder if we can lower it.
  10. rhenderson

    rhenderson New Member

    Good idea thanks, we will give that a shot!
  11. qwas123

    qwas123 Screwfix Select

    - There's no "DPM under the door" - and no sign of a DPC under the outer skin of bricks.
    - There's a short, strip of DPC hanging off the inner skin of brickwork.
    - No air bricks can be seen - lack of air brick ventilation creates excessive condensation below suspended floors. Excessive condensation can lead to dry rot.
    - Bricks have been loosely laid without mortar.
    - All joist tails should have come to rest on the inner skin of brickwork ie. the joists should have been longer.
    - No noggins have been used.
    - The bottom rail of the Pvc frame is barely perched on the outer bricks.
    - The oversite is a damp, soggy looking mess of what?
    - The exterior ground level and the interior oversite might be too high.
    - Wood chips on loose bricks is problems waiting to happen.

    In short, the whole flooring thing needs renewing & re-doing.
    rhenderson likes this.
  12. The Happy Builder

    The Happy Builder Screwfix Select

  13. rhenderson

    rhenderson New Member

    Thanks, what a strange floor. I wonder if they created some additional problems when the patio doors were put in as well.

    Sounds like we have our work cut out for us!
  14. rhenderson

    rhenderson New Member

  15. Astramax

    Astramax Super Member

    In that case......Nessie?
    rhenderson likes this.
  16. Alan22

    Alan22 Screwfix Select

    Is it me or are the floor joists just sitting there?
    rhenderson likes this.
  17. techie

    techie Screwfix Select

    Think Id be tempted to put in a solid floor
    rhenderson likes this.
  18. rhenderson

    rhenderson New Member

    Yea, at least on this side of the wall!
  19. rhenderson

    rhenderson New Member

    It has crossed our minds but we wondered if it would be too time-consuming/disruptive as we'd need to do the whole bottom floor. We might look into it though if the floor needs redone anyway as it gives us better insulation options as we currently can't insulate with such a small gap.

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