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Wet floor in doorway cavity

Discussion in 'Building' started by Dylan T, 20 Jan 2021.

  1. Dylan T

    Dylan T

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    Hi all - I've had a kitchen extension finished by a local builder, who has passed it over to me to do the finishing (paint and tile). However the concrete in front of the bifold doors in the cavity will not dry and I'm not sure whether to be concerned or not. I have the glazier who fit the door coming back on the weekend to sort something else out and also need to speak to the builder soon so was hoping someone could help me find the right questions to ask, because I'm a little unsure if there are any potential problems at the moment and what they might be.

    The concrete that is wetter in the image was laid a long time after the drier stuff, and even the plaster on the walls are taking a while to dry, so perhaps it could just be needing to have more patience. I have just fitted rads on the wall, so its warm now but it wasn;t too warm earlier, but I have had two dehumidifiers running. It has been probably 3 weeks since the wetter concrete was poured, but I'm not sure how much water was underneath when it was poured if any as until then everything was pretty sodden.

    Should there be any insulation under that concrete and if so would it be under the dpm or between it and the concrete?

    It's rained a couple of times in the last week and it doesn't seem to get any worse when it does. I can also dry it out patches with a heater, but it comes back soon after. This all makes me think that perhaps its just really wet concrete that is acting as a sponge and taking a long time but it does seem to be going on a bit now, and I can't tile until sorted.

    There is still some cold air coming in under the door in the gaps in the expansion foam so I'm aware that is one of the coldest parts of the room too.

    Thanks so much
     

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  3. Bonni

    Bonni

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    When you build the opening, before you get to DPC level, you need to decide if you're fitting the doors to the cavity or as in your case, to the outer leaf. I always go for cavity if the customer is not bothered.

    If it's fitted to the cavity, the outer brickwork is stepped in a couple of inches, then an upstand of DPC, then the 1200g DPM, then an upstand of 25mm Kingspan and then the main kingspan on the floor. The inner leaf bricks/blocks will be below all that. Then the floor concrete goes up to the 25mm Kingspan. That's there to stop cold bridging.

    In your case, outer brickwork will be flush all the way across, again you don't have any inner bricks/blocks and you repeat the DPM and Kinspand above upto the outer leaf brickwork. Then the door fitter must know how to place very wide vertical DPC on the reveals so it fully covers the reveal and wraps round into the cavity.

    Under the DPC in the picture, sounds like there's brick/block under there and the floor concrete stopped to that. Then he's just filled the gap (the cavity) with mortar. So it's all wrong imo, obviously without seeing it, it sounds/looks wrong.

    Or in simpler terms, the doors sit on the outer leaf brick whether it's flush on the outside or stepped in and the upstand of DPC, DPM, 25mm Kingspan is between the brick and concrete floor.
     
  4. ^woody^

    ^woody^

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    Its wrong. There are lots of threads about how the threshold should be finished
     
  5. Dylan T

    Dylan T

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    Thanks - as in this would fail regs and
    Bloody hell im in over my head here, i barely understood a word of that haha. Thanks for the reply, i'll gave a google in a bit to better understand some of those terms and then get back to you!
     
  6. Dylan T

    Dylan T

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    Thanks - the local building inspector saw it just before the doors went in so how wrong is it? Just confused if he's missed something
     
  7. ^woody^

    ^woody^

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    It needs the floor DPM going across the threshold then up the wall and into the DPC joint under the frame. Then it needs insulation up against the external leaf to prevent cold bridging, then the threshold is filled in.

    And before that it should have had the insulation under the floor spanning across the threshold. There may be images or more descriptions in the many other threads.
     
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  8. Dylan T

    Dylan T

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    Okay thanks for the help so far - please bare with me - its very much appreciated.

    Yes it was fitted to the outer leaf (I was't even asked or would have thought about it).
    I've cut away a little of the plasterboard (can cover with skirting later) to try and see if the glazier used a vertical dpc you speak of, and I can't see anything. It seems that the door is fitted to the blockwork on all sides, with just the fixings and expanding foam filling the gap. There is that thicker DPC tape running up the wall that the builder seems to have run up and folded in so it covers both the edge of the door frame and the cavity. (Shown in my images as A)

    'B' also shows that more tape seems to run along side the breadth of the bottom of the frame, but never goes under it.

    I've also made a cross section to show what I THINK is going on. Plus I've read a bunch of threads which tbh all seem to conflict in various ways but the most consistent i think is represented in the coloured diagram ive attached which seems to be what you're saying; that the insulation should come across completely to the door. Does that diagram look the correct way of doing things?

    Am I then right in saying the major problem here is that the concrete in my cavity is making direct contact with the outside wall and therefore bring in all all that cold, hence the term 'cold bridging'? Thanks so much for your help.

    Update: I've just looked again and the door is actually sitting on a strip of dpc tape (not sure if that's the right term but you know what i mean)
     
    Last edited: 20 Jan 2021
  9. Dylan T

    Dylan T

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    Thanks, going through now but not easy for a novice like me to understand it all; my brain is almost fried already from this bloody build, last thing I need. I think I've addressed some of this in my last quoted post; as it was do you know if this would fail regs?
     
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  11. ^woody^

    ^woody^

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    This is the principle. The continuous DPM and insulation upstand are the crucial.

    What you have there is not compliant.

    [​IMG]
     
  12. Dylan T

    Dylan T

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    Thanks for the reply Woody. Sorry if I sound think (probably because I am) but what I'm confused about is that to my mind that would mean the inner skin would have to be lower, at least near the door. I've watched a few videos of extension time lapses and door installations and they all seem to follow the method as shown in my image below, where both skins are the same height and the floor is screeded to that height. Am I missing something?
     

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  13. 23vc

    23vc

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    Correct, the inner skin should be non existent within the doorway area and the slab should extend out to the door threshold with dpm lapped up and under the door, as per woody above
     
  14. Dylan T

    Dylan T

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    Thanks - it's really frustrating and confusing as the team build homes all across the place, including for some big firms, and have the local building control officers on site all the time. What is the worst that could happen with it like this; damp or just really cold at that little stretch? And is the only solution removing that door and digging up that part of the floor?
     
  15. Dylan T

    Dylan T

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    Am I also right that upstand insulation should have been used around the entire perimeter?
     
  16. ^woody^

    ^woody^

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    I've seen the same crap work by the same people for years, and they don't know any better, so it becomes "how I did it on the last job" for them and totally normal.

    Building control just look for certain things and ignore more things. They are not there for your quality control, but just to check a few things mainly based around significant health and safety.
     
  17. Captain Nemesis

    Captain Nemesis

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    They are there to issue a certificate saying that the work complies with building regs. Does this comply with Part C?
     
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