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  1. #1

    Question Anyone used ICF for pond walls

    Iím currently landscaping our garden, including a large in ground pond. Iíve been looking at various construction techniques for both this and a swimming pool. I previously came across ICF (insulated concrete forms) for swimming pools and wondered if anyone had tried this for a pond?

    ICF is effectively a large polystyrene (or similar) hollow block that is easy to transport and lay (they interlock without mortar) and then you fill them with poured concrete. As a result you get a very strong poured wall and also benefit from two layers of insulation.



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  3. #2
    I watched a youtube vid of someone using them for a pond, i would have thought they would be more expensive than a hollow block though

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  5. #3
    I only saw YouTube videos of houses and some pools.

    i found some costs for a block for a pool and given their size, not too bad.

    do you think these can be fibre glassed onto? Given that most people glass onto Kingspan type material? Conscious that this is a different material though and doesn’t have the silver film.

    did the one in the YouTube video you saw have fibreglass?

    Any chance you have the link in your history?

    thanks

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  7. #4
    Found one set of videos, and then followed the links to this blog post...

    https://mnkoilady.com/2016-2017-lower-pond-version-5/

    doesnt really discuss the reasoning behind ICF and it was kindred so doesn’t help with my question about fibreglassing.

  8. #5
    Also found this company that supply ICF including for swimming pool use. They also have a produce called Nudura One, which has a forma one side and the insulation the other, allowing for 1 layer of insulation on the outer edge and a concrete face on the inner edge if I need to go that route.

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  10. #6
    GB, you donít need the silver film to fibreglass to, you could glass straight onto concrete if you wanted to. If using this stuff youíd probably have to tape the joints maybe?
    Also, Iíd presume youíd still require some steel reinforcement within your concrete walls.
    I believe 7N blocks laid flat would work out considerably cheaper unless youíre building something massive , ie, swimming pool size.


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  12. #7
    Quote Originally Posted by bigcarpchaser View Post
    GB, you donít need the silver film to fibreglass to, you could glass straight onto concrete if you wanted to. If using this stuff youíd probably have to tape the joints maybe?
    Also, Iíd presume youíd still require some steel reinforcement within your concrete walls.
    I believe 7N blocks laid flat would work out considerably cheaper unless youíre building something massive , ie, swimming pool size.


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    Hi.

    So it seems that there is a product where you have only one side with polystyrene leaving the concrete to fibreglass to, or also a product where you can have the polystyrene both sides (which is probably easier) which Im unsure about fibreglassing to. I guess I will be best to ask a glasser!

    The pond is 60k litres, so quite a size, I will likely put rebar down as well. In terms of cost, I am paying for labour also, so there will be some savings on that side as it's easier to set these bricks and pour the concrete than moving 7N blocks and laying them. Not sure on the economics of it all, but in my head it should be a similar cost and I get better insulation built in. I'm building a pool also, so potentially using the same system for both.

    There is a similar product directed at the swimming pool market called blokit. https://mypooldirect.co.uk/store/diy...ilding-system/

    They also sell a similar product called megablock, which are £19 each. They have a table with examples of quantities, for 10m x 5m, you need 155 blocks, so approx £3k for the blocks, around 6 cubic metres of concrete, Im guessing £600? Plus the rebar and probably a concrete pump...

    7N blocks from Travis (for example) are £1.70 each, 1125 blocks for 10x5x1.5, so that's £1,912.50. Plus the mortar / sand / plasticiser (not sure how much) and insulation (16 boards x £50.29) £805. I'm guessing around £500 for the mortar / sand etc.

    So that puts blocks at £3,217.50 and ICF at £3,600 + pump and maybe some rebar (arguably for comparison the block wall doesn't have this). But then it's a case of the labour saving which I think will be quite a chunk.

    Add to this that the pond (and pool) that I am looking to build are shaped and not square, I think there will be further benefits to the strength of the ICF wall as it will shape as required (they do bendy ones) versus having to cut all the blocks to get a good tight fit, or packing out with mortar (maybe not as strong?).

    What do you think, am I missing something here? I guess a call to an ICF company will help as this will firm up the costs. Conscious that I've based the costings on a rectangular 10x5x1.5 shape rather than the actual design!

  13. #8
    The vid i saw was ages ago, they wasnt the same at the ones you are looking at they was just a polystyrene version of a hollow block but they slotted together, you would have to find out if the resin would melt the polystyrene or not, the sheets of insulation glassers use is polyurethane. you would deff need rebar though and i dont think a truck and a pump would wait about for you to fill up all the cavities

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  15. #9
    Presumably it's "Solidbric" you're looking at? If so, you will deffo need some kind of steel reinforcement as concrete has absolutely zero tensile strength. How much you'd need I can't answer, the suppliers would probably have a structural engineer look at it I would have thought.
    The swimming pools we draw for one of our customers are normally cast in-situ reinforced concrete 200mm thick with around 80mm of EPS insulation (the blue stuff) under the slab and on the outside of the vertical walls.
    I guess if you're building a massive irregular shape pond and a swimming pool then the ICF method could work out pretty cost effective just from the savings on the volume of concrete you'd require. Not sure how you'd do nice "curves" if that's what you're doing?
    If you have decent insulation on the outside and just wanted a smooth face on the inside to glass to then you could just line the inside with something like this https://www.ecfibreglasssupplies.co....am-sheets-12mm
    Some might argue you don't need much more than that on a koi pond full stop.

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  17. #10
    I just spoke with a Nudura rep. They have a distribution warehouse near me, so I’m going to pop in this afternoon and pick up a sample. They can form the curves to a radius if required or you can slot the straight blocks to make a free form curve and then use fixing points in the webbing to secure it prior to pouring concrete.

    i will ask when I get there if they specify the rebar requirements.

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  19. #11
    Like giant Lego lol
    Canít wait to see it all come together Anyone used ICF for pond wallsAnyone used ICF for pond walls


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  21. #12
    Senior Member Rank = Yonsai Alburglar's Avatar
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    Polestyrene is a big no-no for fibreglass. Looking at the first video I would have guessed that is some form of PU (polyurethane) foam. If Not You would need a layer beyween the two, but something as simple as pallet wrap (large clingfilm) would work.
    But then the 2nd one says that it is polestyrene, but then it looks like they are using a sheet of PU foam as liner, before glassing it.
    I really like the idea, but why not just use osb as shuttering and poor the concrete in? Easier simpler and cheaper surely?
    Last edited by Alburglar; 13-08-2019 at 11:54 PM.

  22. #13
    I have a sample of the material at home as of yesterday, unfortunately, I'm away now until next week, so I can't take a close up picture or measurements for you, but I'd say it's a good 300mm thick, possibly 200mm inside measurement. The slabs come in 2.4m lengths and stack / lock together in seconds.

    They can be cut to curves, or they can manufacture them preformed to the required curves from cad drawings. So Im going to get quotes for both.

    Figured polystyrene would be a no-no as it will probably melt, but lining it as you suggest is an option. They also have a one sided produce where the inside is lined with a shuttering and then removed leaving the concrete face.

    Shuttering and pouring may still be an option Al, but I'm not sure I'd agree it's easier, simpler and not even sure on cheaper (probably). For poured concrete, we'd need to construct the steel re-inforcing manually whereas the Nudura has locators to hold the rebar in place and lock it to the ICF. Cheaper, probably for materials, but overall maybe not since I'm paying for labour.

    In addition, you have to factor in the built in insulation that ICF comes with vs buying and manually fitting Celotex.

    That's the purpose of the exercise really, see what's the best approach from a cost / time perspective. I appreciate if you're fully DIY'ing the pond that labour is less of an issue (at least for cost, maybe not time), but our garden project is significant and I simply couldn't do it all myself (even if I didn't have a bad back!).

    Cheers for the feedback though. I'll pop some details of the sample up next week and let you know how I get on.

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  24. #14
    Senior Member Rank = Yonsai Alburglar's Avatar
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    I was thinking of using the rebar grids (the ones they use in concrete bases) to build a big cage and then shutter that in. Although shuttering can be quite substantial structures it is simple to achieve. For the corners (of the concrete) you could 90 bend rebar and cable tie that to the grid panels.

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  26. #15
    Extreme Koi Member Rank = Jussai bowsaw's Avatar
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    if the form is polystyrene then the solvents in grp and the wash down with acetone would destroy it more than likely as they have the ability to degrade or dissolve a wide range of polymers
    the slow pond build thread

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  28. #16
    The manufacturers did say anything solvent based would melt it. They did also suggest a layer of render could be added and then glassed though, do you see any problems with this?

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  30. #17
    Senior Member Rank = Gosai Sim's Avatar
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    Why not just get catering size foil and wall paper the wall after with it.
    I know a couple of glassers that use it over damp areas when working.
    Just fibreglass straight over the top of it after job done :-)

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  32. #18
    Extreme Koi Member Rank = Jussai bowsaw's Avatar
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    Quote Originally Posted by GadgetBazza View Post
    The manufacturers did say anything solvent based would melt it. They did also suggest a layer of render could be added and then glassed though, do you see any problems with this?
    well hopefully they don't mean all solvents, bit hard making cement with out water

    what ever you coat it with needs to ensure it can't let the wet grp soak through, or it will leave a cavity and weak point.
    the slow pond build thread

 

 

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