Amtico instal over wunda UFH issues

Discussion in 'FAQ Section For Consumers' started by TJP, Apr 25, 2022.

  1. TJP

    TJP Active Member

    25
    0
    1
    Hi
    Looking for some advice please. We did a whole house refurb last year and have had issues with the 80sqm amtico floor installation which fills the downstairs since we moved back in November 2021.

    there are two separate issues, the more concerning issue is the impact of cracking to the screed, but I’ll also include reference to an adhesive issue for completeness.

    prior to the flooring installation, the plumber laid a wunda ufh system, adhering the boards to a concrete screed from the 70s after the usual prep and priming, using the adhesive provided by wunda.

    The following week the floor fitter came to start the installation of amtico spacia, small planks to be laid herringbone. He primed and used level it renovate, this used just over twice the quantity of latex he expected and quoted for, but I swallowed the extra cost as I appreciated he wasn’t so familiar with a wunda ufh system, and the fact that some channels in the boards would not be filled with pipe (therefore drinking more latex) is natural due to the design of the product and therefore would use more latex than an instal over an ufh system that sits in a screed.

    all seemed good. The fitter came back a month later to finish a section next to sliding doors that were delayed. ivc high temp adhesive was used.

    first issue came a month after that when we moved back in November. A week prior to moving in the boiler was commissioned and ufh fired up for the first time. The plumber increased the temp at 1 degree per day increments, but we were surprised to see some areas lifting just after we moved back in. It seemed the glue had failed, we put it down to a dodgy batch used for the last section to be relaid, and so the fitter came back and relaid part of the installation.

    a month later in December we noticed the glue was failing in other parts of the install, and some worrying gaps were appearing between some tiles that were adhered well. Fitter came back again, used karndean high temp adhesive instead, and this seems to have worked well. The gaps were acknowledged but something that would need more inspection.

    since then, I feel somewhat stuck between the fitter and the plumber to work out exactly what has gone wrong, how to fix, and who will pay.

    the fitter lifted a section of the gapping amtico tiles. There is a crack in the latex running along the length of the gapping. From the many photos I took during installation, this seems to be running along a joint of the wunda boards. The next step seems to be to lift a larger section to inspect the cracks, and to determine if this is also along a joint of boards.

    Wunda say they can’t tell if this is caused by the boards not adhered properly to the subfloor, or due to the wrong screed being used (their technical docs say to use level it two rather than level it renovate). So I am left with the plumber blaming the screed and the fitter blaming the ufh installation, and I doubt we will ever know the truth. I’m waiting for a call back from Instarmac to understand what the difference is between level it two and renovate, but it’s probably more than I need to know.

    in terms of resolution, not perfect but is the best option to fill the cracks with feathering compound and relay the floor, you’ll see in one of the picks there was a big crack in the screed filled with feathering compound before the final day fitting, as above a month after the instal started. There has been no issue with the floor above this filled crack. or should I insist on the whole job being started again, new screed, new floor installation?
    and in terms of the adhesive issue - I’m worried if it’s not all reglued over time it will fail and we will be constantly dealing with it piecemeal (still some sections are coming up from time to time, some sections completely stuck down)

    Does the cracking on the joins of wunda boards prove there is an adhesion to concrete subfloor issue? Or could this just be a coincidence and it’s the wrong screed causing the issue.
    It’s been a very expensive install, including both ufh and amtico, and I want this to last for 30 yrs as I’ve been led to believe it should. I also don’t think I should have to pay to get this fixed.

    any advice greatly appreciated. Thank you
     

    Attached Files:

  2. Rugmunching

    Rugmunching Well-Known Member

    3,266
    547
    113
    I would have thought the level it renovate would be the more compatible instead of the level it 2 due to the fibre reinforced compound....but instarmac screeds are crap in my opinion, had nothing but issues with it when I used it the handful of times few yrs ago so I don't even entertain it anymore.


    What temperature have you ran the ufh up to?

    Did the fitter do a semi/wet set fitting method gen laying the parquet?

    Did he reapply fresh glue on them edges after he fitted a few columns (noticed from one of the pictures a fair bit left that might have been late placement?)

    How thick is the screed over the top of that UFH?

    Have you had any adhesive seep through any of the joins of the amtico?

    How soon was the heating introduced after the amtico was installed?
     
  3. Rugmunching

    Rugmunching Well-Known Member

    3,266
    547
    113
    *gen = when :rolleyes:
     
  4. TJP

    TJP Active Member

    25
    0
    1
    Thanks, yes the fitter says he always uses level it renovate with ufh due to fibre reinforcement, but if Instarmac say you should use LT two I would expect there to be a reason…

    the screed is thicker than the minimum 3mm specified by wunda, It is c. 5mm, they did it in two passes on consecutive days as the first layer didn’t appear to have covered well

    when the fitter laid the parquet he reapplied glue over the the joins where the sections of adhesive meet. In the pic you noted I think that is where the two sections of glue met, with one half of the tile’s back covered in the glue, the other half less so. It seems a coincidence this is where the crack is present. The failing glue hasn’t been limited to those joins, it’s all over the installation. Not sure what a wet set is, it was ivc high temp adhesive that was used.

    We have run the input of hot water supply up to 40 degrees, the system has probes to stop the surface temp going above 27 degrees as specified by the manufacturers. We got up to 40 degrees in 1 degree increments, waiting on plumber to confirm where he started. The room stats have not gone above 21 degrees

    There was a bit of adhesive seeping through some of the joins, I put that down to poor light at the end of the day (no lighting at that point of the Reno) and the fitter cleaned this off the tiles on a subsequent visit.

    heating was turned on 1 month after final instal finished in mid November, and 2 ,on the after the first sections of the job were finished (fitting was 3 days in sep and 1 day in oct)

    thanks for your help
     
  5. TJP

    TJP Active Member

    25
    0
    1
    this pic might help. The thicker line is his pencil line where the two sections met, the thinner line is the crack in the screed, and you can see the variation in how the adhesive bonded to the back of the tile. So a good example of the two issues at play simultaneously. The gapping in this section seems to be the crack rather than an adhesive issue.
     

    Attached Files:

  6. Paul webb

    Paul webb Well-Known Member

    945
    105
    43
    So the system had never had hot water running through it, before the screed was laid?
     
  7. TJP

    TJP Active Member

    25
    0
    1
    No it didn’t, advice I received was that for wunda you can fit the boards and pipes, then lay flooring, then fire up the ufh at a later date provided you turn it up gradually. I understand this is different to the ufh systems that sit in screed rather than boards.
    Should the ufh have been commissioned prior to the flooring being laid?
     
  8. Paul webb

    Paul webb Well-Known Member

    945
    105
    43
    I was just thinking that it might possibly be the initial expansion of the pipes, i know any expansion of the pipes would be minute, but add lots of pipes together and it might be enough to crack the screed, i might be wrong, but it was just a thought, but if by chance I'm right, then it should mean that no more cracks will appear
     
  9. TJP

    TJP Active Member

    25
    0
    1
    Thanks. Sounds like a good possible theory, but I’d expect wunda to advise you to commission the ufh before screed and flooring if this is a potential risk. The big crack that was filled prior to the final day’s installation without any subsequent issue in the floor laid on top also supports the theory no further cracks will appear…
     
  10. TJP

    TJP Active Member

    25
    0
    1
    Another point occurred to me - it’s interesting that the section of the adhesive to one side of the crack shows no adhesion whatsoever to the tile, whereas on the other side of the crack there is good adhesion. I’m obviously no expert here, but that seems a very strange coincidence if it has nothing to do with the underlying issue…
     
  11. dazlight

    dazlight Super Moderator

    6,463
    1,520
    113
    So why wasn’t there a epoxy liquid Dpm done on the 1970s concrete under the UFH ?
     
  12. TJP

    TJP Active Member

    25
    0
    1
    Good q, I’ll check with the plumber exactly what was laid on top of the 70s concrete. I remember he primed it with something the day before the boards were installed, not sure of the exact spec
     
  13. TJP

    TJP Active Member

    25
    0
    1
    I have the plans from when the house was built in 1975, which makes reference to a “polythene dpm” - and according to wunda you only need to start with a liquid dpm if no dpm is present. is it best practice to apply a liquid dpm for a property of this age?
    thanks for your help
     

    Attached Files:

  14. Paul webb

    Paul webb Well-Known Member

    945
    105
    43
    That's why we test anyway, the dpm may be present, but you can't even guarantee it was intact the day it was laid, let alone 48years later
     
  15. TJP

    TJP Active Member

    25
    0
    1
    Ok thanks. My plumber or floor fitter didn’t mention anything about the dpm before either the wunda ufh or the screed then amtico went down.
    What would you suggest that I do in this case? Lift the dodgy bits or floor, patch the cracks, relay and hope for the best, or something else?
    I’ll ask the plumber if he did anything to test the dpm but I doubt it, we were taking 2 or 3 times per day at that stage of the build.
    Many thanks.
     
  16. merit

    merit Well-Known Member

    7,525
    1,567
    113
    Sounds like your having the same issues we see on all of these ufh systems. No moisture test taken to determine if there is any rising damp. Introducing a ufh system that will make the effects worse if there is any damp. The ufh system should of been fully commissioned and run for 2 weeks before any flooring was installed over it. That will release the last bit of moisture and cause the cracks. Doing it after a impervious floor covering had been installed is not a good idea. Plumbers install the boards that become your new subfloor. they are often not well bonded or level. Who’s at fault? Sounds like both trades are not really trained to install or overlay on your system.


    Sent from my iPhone using Tapatalk
     
  17. TJP

    TJP Active Member

    25
    0
    1
    Thanks. I spoke to the plumber earlier - he didn’t see the need to test the concrete floor for dampness as it was “clearly bone dry” with no sign of dampness. I can see his point, the concrete base has been visible since March when everything was ripped out and the ufh was fitted in September, he had been working on the build throughout that six month timescale. It’s curious that wunda don’t include anything in their technical docs or instructions indicating the ufh should be commissioned and run for at least 2 weeks before fitting flooring like this. The plumber has gone through the process step by step with wunda and they have not found fault in any of the processes. Are you saying that wunda don’t advise the best practice approach to fit their own products? I would agree the fitter certainly didn’t know what he was doing with this system, but from what I hear the plumber regularly fits this wunda system and has never had an issue before. Painful that I’m the first there.
    Focussing on the solution, given it’s not going to be an option to rip everything up and start again would you agree the best thing to do is fill the cracks, relay the flooring and hopefully it will be good enough?
     
  18. Paul webb

    Paul webb Well-Known Member

    945
    105
    43
    Lol, I'm sorry to laugh, but i don't recall seeing "Looks dry to me" in the British standards, it could rain on a concrete drive for a week, then you have one sunny day and it looks bone dry, but that's just the surface you are seeing
     
    • Like Like x 2
    • Agree Agree x 1
    • List
  19. TJP

    TJP Active Member

    25
    0
    1
    I get what you’re saying, but surely if you have rising damp there would be some evidence of it? We took this house back to brick, wiring plastering plumbing everything from scratch. Surely you’d see some evidence of damp if there was some present? Are you saying no matter what the best practice is to test the concrete slab for moisture prior to doing all of the above?
     
  20. tarkett85

    tarkett85 Well-Known Member

    3,089
    468
    83
    Always test the concrete, essentially it’s a big sponge which will take in moisture from the ground and air then have to release it (path of least resistance usually straight up) which is what causes issues, the Rh% must be below 75% for British Standards and manufacturers instructions you can’t guess at this and must take a proper reading with a sub surface hygrometer which takes 72hours, otherwise adhesives, incorrect primers and screeds will fail.


    Sent from my iPhone using Tapatalk
     

Share This Page