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    • CommentAuthordelprado
    • CommentTimeOct 16th 2017
     
    Has anyone done this and care to share any wisdom? Full filling with EPS still makes me nervous so now I am thinking about just doing it all properly using geocell and making a solid floor.

    Thanks
    • CommentAuthorjfb
    • CommentTimeOct 16th 2017
     
    What makes you nervous? That it might float? Or sink?!
    • CommentAuthordelprado
    • CommentTimeOct 16th 2017
     
    the fact that there is no evidence it is ok to use EPS, and the fact that, on further research, moisture does not need to condensate in order to create issues.
  1.  
    Hi, in a similar position. Can't offer any advice but curious to know what your floor build up will be if you choose the eps route? Thanks
    • CommentAuthorSilky
    • CommentTimeOct 16th 2017
     
    Search for limecrete and you will find plenty of threads.

    I'm doing this at the moment, I used Ecoglas and it''s all down. Currently making up the slab on top. 3 rooms and a hallway, total around 100 m2. I'm also in a flooding area which makes it extra silly. I decided in the end to do concrete islands, i.e. slabs of concrete and leaving a 20 - 50 cm border around the concrete to to back fill with something more insulating and breathable. I'm trying both EPS-concrete and Leca-limecrete with NHL5. I started with the EPS but now figure the Leca-lightcrete will be more airtight. Because of uneven walls my expansion strip is on the edge of the concrete islands, where I can attach a compressible strip to the clean lines of the concrete and then the limecrete goes between this and the walls.

    I've used a Belle electric wacker plate, 50 Kg, 100 Hz and it worked fine, we compressed in 2 layers and went over each layer 2-3 times, therefore no problem with fumes / carbon monoxide working indoors.

    Glass foam delivered in 2m3 bags on palettes, getting the palettes off the lorry is a bit difficult without a forklift, you need a smooth un-loading area ( I had to lay boards over a cobbled yard ).

    I wasn't over happy with the Eco-glas product, but I stuck with them as they are local and price is ok. Advertised as a 10/60 mm aggregate, in reality the pieces are everything from dust to 150 x 100 x 100 mm. I complained but they didn't react. The larger pieces easily break down on compaction, but this doesn't help you to get the loose stuff levelled out before compaction.. bit of a pain. Smaller sizes are available but they're double the price.

    The easiest way to get the stuff out of the big bags is to cut them open near the bottom and then just let it drop by gravity into a container / wheelbarrow or whatever, goes very quick, but shame to destroy the bags.. we were told to throw them away ( no deposit ).. which seems mad as they must cost quite a bit. Not very green or eco at all, so I'm keeping them and trying to think of a re-use.

    For my situation the slab is acting as a counterweight, just in case the foam glass tried to float.. I'm dong the concrete island/hybrid slab because I simply don't have the resources to mix so much Limecrete and in the end I'm not convinced it's needed across the entire floor. The concrete doesn't need to be super strong, so mixing quite runny helps to improve the breathability of the concrete ( as the concrete dries the water leaves micro-pores ).
    • CommentAuthorSilky
    • CommentTimeOct 17th 2017
     
    Another tip, which I was lucky to realise before the 1st concrete pour, if you're not using a DPM then give the foam glass a damn good soaking before trying to put limecrete / concrete on top, it really sucks water away quickly
    • CommentAuthordelprado
    • CommentTimeFeb 24th 2018
     
    Thanks all. I am going for a screed-less finish - geocell, then woodfibre boards, then lithotherm clay UFH tiles
  2.  
    Ive used EPS under slabs and screed for years with no issues to date, could you expnad on the issues you've read about it
    •  
      CommentAuthordjh
    • CommentTimeFeb 24th 2018
     
    Posted By: delpradoThanks all. I am going for a screed-less finish - geocell, then woodfibre boards, then lithotherm clay UFH tiles

    Two questions:
    (1) What is the airtightness barrier?
    (2) How are you going to ensure a flat floor finish?
    • CommentAuthordelprado
    • CommentTimeFeb 25th 2018
     
    I'm still undecided as to what I am going to do for airtightness.

    I like the elegance of simply barging the bricks with cement below DPC and then relying on the fact that mud is airtight!

    However if you are asking about what is stopping vapour transmission internally into the floor then the only thing that can do that is a membrane, so i actually think I am going to do both. With the membrane on top of the wood fibre.

    In terms of levelling - datums to get it measured right, then just being careful with a tamper.
    • CommentAuthordelprado
    • CommentTimeFeb 25th 2018
     
    • CommentAuthorJulio
    • CommentTimeFeb 25th 2018
     
    <blockquote><cite>Posted By: delprado</cite> In terms of levelling - datums to get it measured right, then just being careful with a tamper.</blockquote>

    In my experience it could be tricky to get this a level as might be required for the wood fibre board. What wood fibre were you thinking of using?
    •  
      CommentAuthordjh
    • CommentTimeFeb 25th 2018
     
    Posted By: delpradoI'm still undecided as to what I am going to do for airtightness.

    However if you are asking about what is stopping vapour transmission internally into the floor then the only thing that can do that is a membrane, so i actually think I am going to do both. With the membrane on top of the wood fibre.

    Yes, that's what I was asking about. So you have decided. :bigsmile:

    In terms of levelling - datums to get it measured right, then just being careful with a tamper.

    Sorry, I wasn't clear. What I meant was where is the structural element that provides a solid surface that won't move when point loads are applied? Also, as Julio said, levelling won't be as easy as you seem to expect. At least do a trial area first if you wish to use your suggested approach.

    Might use this instead

    Ah, now that's an interesting product system. I haven't seen it before; is it new? I might have considered it, using the dry levelling compound, for my ground floor instead of battens and chipboard. How much does it cost?

    Note that the brochure is quite clear that it can only be installed over a continuous structural floor. See my Q2.
    • CommentAuthordelprado
    • CommentTimeFeb 26th 2018
     
    Im not sure if its new but I'll ask Fermacell technical today as I am calling them. Fermacell products look all round fantastic to me, and I plan to use it everywhere on top of my IWI as a strong board to fix into. Never thought something could convince me of dry lining! But with the absence of wet in my floor I am becoming a dry trade enthusiast obviously!
    • CommentAuthordelprado
    • CommentTimeFeb 26th 2018
     
    That floor is 30 years old Dave!

    I think on reflection no reason to use it in my case though as the lithotherm tiles are really my screws replacement and all the fermacell product is wood fibre (which I’m using anyway) and their 2 layers of 10mm dense gypsum board as the screws replacement
    •  
      CommentAuthordjh
    • CommentTimeFeb 26th 2018
     
    Posted By: delpradoThat floor is 30 years old Dave!

    Sorry to be dense, but what floor and why is its age relevant?

    the lithotherm tiles are really my screws replacement

    Eh?

    But again, you have no structural layer. The floor will not be stable.
    • CommentAuthordelprado
    • CommentTimeFeb 26th 2018
     
    You asked if the fermacell floor product is new - thats what I meant - its 30 years old.

    the geocell is a structural layer.

    When I talk about lithotherm being a screed replacement I mean purely in the sense of thermal mass
    •  
      CommentAuthordjh
    • CommentTimeFeb 26th 2018
     
    Posted By: delpradoYou asked if the fermacell floor product is new - thats what I meant - its 30 years old.

    Ah, thanks; I said I was being dense! I'm surprised I hadn't come across it before.

    the geocell is a structural layer.

    No, it isn't, not in the sense required. A concrete slab is a structural layer - it's rigid and will distribute point loads without moving. So is e.g. T&G chipboard on timber joists. Loose aggregates are not structural - apply a point load and they will move.

    When I talk about lithotherm being a screed replacement I mean purely in the sense of thermal mass

    Ah, right. I didn't understand the reference to screws?
    • CommentAuthordelprado
    • CommentTimeFeb 26th 2018
     
    Sorry yeah screws was a screed typo!

    re geocell - thats why the woodfibre is there, above it, but below lithotherm tiles, to distribute the load with its high compressive strength
    •  
      CommentAuthordjh
    • CommentTimeFeb 26th 2018
     
    Posted By: delpradore geocell - thats why the woodfibre is there, above it, but below lithotherm tiles, to distribute the load with its high compressive strength

    Yes, but it will still move if a point load is applied to the edge of a sheet.
    • CommentAuthorSilky
    • CommentTimeFeb 26th 2018 edited
     
    You won't get the geocell flat enough for board laying, I would suggest either skimming the top with an nhl screed until it holds together then sand to level OR geotextil + another go on the wacker plate + sand.. then you could lay your air tight membrane on the the sand. Then it's probably best to have some battens and then more fill between the battens before boarding,

    I wanted to give an update in case it is useful for anyone to know, we had 3 severe floods with water up to the edge of the house in January, high humidity before Christmas and very cold weather the last few weeks (-10 tonight).. the new ground floors and surrounding stone walls are bone dry, so very happy so far, considering the concrete should still be drying and that part of the house has no heating, it's looks like a good result, so very happy. By comparison we had a similar flood back in June 2013 and the part of the old floor that was concrete was damp for several weeks, so it seems like the glass foam is doing the job of allowing the floor to dry quickly and stay dry.. and limecrete wasn't needed.
    • CommentAuthordelprado
    • CommentTimeFeb 27th 2018
     
    Lithotherm has done what I am suggesting in hundreds of houses in Germany. I'll go back round the loop with them to get them to comment. The thing I am not mentioning is that I am planning a pea shingle layer of 10mm for levelling.

    Silky, were you screedless? WHat did you use on top of geocell?

    Worth pointing out that the fermacell system is also screedless
    • CommentAuthorSilky
    • CommentTimeFeb 27th 2018
     
    no, not screedless, concrete 'islands' surrounded by pea shingle (leca / liapor) set with hydraulic lime, to give a breathing border for the walls

    We had to lay formwork on top for the concrete, so we tried very hard to get the geocell level, it's very difficult, because you have to squash it so that it stays in place, but when you squash can't control the level, then you add a little more but it's really a labour in vain, so the idea with pea shingle for levelling is good but I would say 50/60 mm is more realistic, and using battens will make the job easier. Another trick is to fill up a large container with the geocell and break it down into smaller pieces (sledge hammer, hand stamper, or wooden post with handles like crushing apples to make cider) and then you have something a little finer for levelling that is cheaper than pea shingle), we found this useful for making up the rough level
    •  
      CommentAuthordjh
    • CommentTimeFeb 27th 2018
     
    Posted By: delpradoWorth pointing out that the fermacell system is also screedless

    But it still requires a solid structural subbase underneath it. Read the installation instructions carefully, especially where it says the Fermacell system is not 'spanning'.
    • CommentAuthordelprado
    • CommentTimeFeb 27th 2018
     
    the geocell is solid and structural when compacted? There is no span
    • CommentAuthordelprado
    • CommentTimeFeb 27th 2018
     
    •  
      CommentAuthordjh
    • CommentTimeFeb 27th 2018
     
    Posted By: delpradohere is an example where it has been done in the UK

    It's the Cemwood that is critical and where the product documentation contains the appropriate wording, AFAICT. But it still seems to need a solid support underneath it. How would it be separated from the Geocell? I'd think it would need a form fitting membrane with adequate tensile strength. Maybe one of the strong geotextiles as John suggests.

    I'd suggest you really need to get an approved build-up for the whole structure from the manufacturer or perhaps a main distributor of the products.
    •  
      CommentAuthordjh
    • CommentTimeFeb 27th 2018
     
    Posted By: delpradothe geocell is solid and structural when compacted? There is no span

    Have you got some and tried walking on it?
    • CommentAuthordelprado
    • CommentTimeFeb 27th 2018
     
    What I am suggested is approved by lithotherm - geocell still talk of limecrete screed.

    i am using gravel instead of cemwood as chris from back 2 earth reckons its easier to level
    •  
      CommentAuthordjh
    • CommentTimeFeb 27th 2018
     
    Posted By: delpradoWhat I am suggested is approved by lithotherm - geocell still talk of limecrete screed.

    Ah, that sounds encouraging. Do you have a link to their document?

    i am using gravel instead of cemwood as chris from back 2 earth reckons its easier to level

    Make sure to get the correct spec of gravel.
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