Building an ICF Pool (UK) with Nudura. Some questions.

[richie967]

Hi Forum,

I've previously posted here and found it to be an extremely helpful resource. I ended up with a really nice family sized which we loved! It was 5m x 3m x 1.4m. I have since moved house and am building another pool, but this time out of ICF. Here's the basics:

- Pool internal size is slightly larger at 3.5 x 6.5 x 1.4 constant depth.
- 2 low level suction points on long wall
- 2 return jets back to pool either side of skimmer about 50cm below waterline.
- I am building corner steps into the pool in one corner
- I am proposing to use 200mm core Nudura forms which have 67mm or insulation either side making a total wall width of 337mm.
- A bag liner is out of scope due to the steps in the pool. And a weld on-site liner is prohibitively expensive.
- 200mm raft with 2 layers of 8mm mesh (Not asking for advice on this as a SE has specified)
- 50mm XPS under slab

Questions:

1. Has anyone successfully rendered straight onto Nudura EPS foam and used low budget epoxy paint (which I know isn't ideal as the membrane. Any details of products for this would be helpful! I've read that you can use sand/cement, 2 layers, and epoxy, and also read about acrylic render?
2. I've seen a self adhesive water proof membrane used on the foam, but i'm guessing i'd only use this on the outside of the walls.
3. In pool steps, I am guessing I'd insert some steel into the floor and walls (prior to the pour) to tie the steps to the walls and floor.
4. Should I be considering Nudura ONE (one sided ICF) over regular Nudura forms so that I can render straight onto the concrete as a more tried and tested method?

Kind Regards, Rich

[Teapot1]

Hi Rich,
Having corner steps doesn't rule out a bag liner, having done the same for a customer provided your measurements are accurate. I will just say the factory messed up 1st time and somehow made the steps in the opposite corner! 2nd time was ok.
Two low level suction points? To what aim, why?
How many skimmers and only two returns?

Use the 200mm Nudura, thin coat with BASF waterproof render (exact product escapes me but will look it up later and reply) embed render mesh into that and then a second coat of the same. Epoxy paint is shite, had such high hopes for it but it let me and friends down after a short time. There are polyurea coatings and Ecofinish as well.

[Smokeyjon]

Following with interest as I’m also planning a small ICF pool in either nudura or R-wall (hoping to get away with 150mm core though reinforced with horizontal and vertical steel).

I’m favouring a bag liner on budget grounds but having thought about steps did also consider adding plastic/grp(?) roman steps which would allow a cheap bag liner to be cut to accommodate. Maybe something to consider? Cheapest I found was this https://www.agbudget.co.uk/product/roma ... -6in-deep/

[richie967]

Hi Rich,
Having corner steps doesn't rule out a bag liner, having done the same for a customer provided your measurements are accurate. I will just say the factory messed up 1st time and somehow made the steps in the opposite corner! 2nd time was ok.
Two low level suction points? To what aim, why?
How many skimmers and only two returns?

Use the 200mm Nudura, thin coat with BASF waterproof render (exact product escapes me but will look it up later and reply) embed render mesh into that and then a second coat of the same. Epoxy paint is shite, had such high hopes for it but it let me and friends down after a short time. There are polyurea coatings and Ecofinish as well.

Hi Teapot,

Thanks for the note, for some reason I thought that having anything other than a straightforward rectangle would mean an on-site liner. I guess a bag liner made for steps would be a bit more tricky to fit. But good that I've got that as an option if I run into too many difficulties with the rendering and paint. I was thinking two low level suction points, basically to suck the water out of the pool from near the base to enable the water to circulate through the filter and heater? Basically the same setup that I did on the last pool. No main drains. One skimmer in the middle of the wall that gets the prevailing wind, and two returns. Basically the exact same configuration i did on my last pool. I'll mock this up and update this post with an image later showing the plumbing.

Yes, planning the 200mm Core Nudura. That was the thickness specified by the structural engineer as well. With an 8mm steel every 200mm, and horizontal ring steels in each course of block.

RE: Render, Just had a look at the BASF stuff, it is acrylic by the looks of things. Can't seem to find an equivalent in the UK. Would this work It's a Mapei product. Not acrylic. But they also supply a Mesh.

I had Epoxy on my Salt pool for a few years and seemed OK. Granted it's cheap and nasty. But i think it's the only way I can really afford to get the pool done. I like the micro cement finishes. But I think they cost a small fortune. I'm a little nervous about rendering over the EPS. And can't find much info on it. I'll take a look at Polyurea coatings and Ecofinish. Not sure if this stuff is available in the UK.

Thanks again.

Hi Jon, thanks for the note on the steps. I'm not keen on the roman end as I like the clean lines of the good ol' rectangle. But it's good to know that I could potentially go down that route if needed. I'll be back in touch with some images showing plumbing plan.

Cheers.

[Teapot1]

BASF Thoroseal, it is available in the UK as is everything I post with products. Yes Mapei do make a similar but the foam boards like Wedi panel and Marmox use Thoroseal or did unless its changed with a rendermesh buried inside the two coats.

When I fit a liner I start at the steps if fitted as it gives the best starting point IMO and using a shop vac allows a fair bit of adjusting before commiting to final fixing.
Polyurea is available in the UK as is Ecofinish, I can look out the contact info if you cant find it.
Glen Burbridge or Ed Simons for Ecofinish 01580 720929 glen.burbridge@ecofinish.co.uk
Sucking water out at low level achieves very little as dirt enters from the surface that is the best place to remove it and the more lower level action you have the less skimmer action so counter productive. Ok as a return to prevent stratification of the water.

[richie967]

BASF Thoroseal, it is available in the UK as is everything I post with products. Yes Mapei do make a similar but the foam boards like Wedi panel and Marmox use Thoroseal or did unless its changed with a rendermesh buried inside the two coats.

When I fit a liner I start at the steps if fitted as it gives the best starting point IMO and using a shop vac allows a fair bit of adjusting before commiting to final fixing.
Polyurea is available in the UK as is Ecofinish, I can look out the contact info if you cant find it.
Glen Burbridge or Ed Simons for Ecofinish 01580 720929 glen.burbridge@ecofinish.co.uk
Sucking water out at low level achieves very little as dirt enters from the surface that is the best place to remove it and the more lower level action you have the less skimmer action so counter productive. Ok as a return to prevent stratification of the water.

Hi Teapot1,

Thanks so much for the response, it's mega helpful!

Base coat Render
After doing a little bit of digging, I think BASF Thoroseal has been rebranded to BASF Masterseal 581. This Everbuild Febtank Super Tanking Slurry seems to come up when searching for the BASF product.

Thanks for the notes on the liner as well. It's good to know.

Finish
RE: EcoFinish - I've emailed Glenn But no response yet. I'd imagine as EcoFinish is a premium product that requires special tools to apply, it will probably be out of my price range!
RE: Polyurea - I've not heard of this before, Initial googling suggests it's also a specialist coating that you need to get people in to do for you as opposed to putting it on yourself. I'll do some more research here.

Plumbing, inlets and outlets
So I've made a visual showing two inlets (where heated cleaned water is being put back into the pool) shown in red. And two suction points either side of the Skimmer (in blue).

https://i.ibb.co/d6X6LrP/Plumbing0-png.png - Can't seem to get an image to work in the forum - hopefully the link above works.

Thanks again! Super helpful!

[Teapot1]

Yes both of the finishes are specialist applied. The Ecofinish is something I nearly bought into but the gun costs a fortune so best left to guys who do it all the time but like polyurea its really quick to apply. Look for polyurea companies outside of the pool industry as the pool industry charge far more than say the roofing companies.

Your original description of your inlets and outlets was why I questioned you but looking at your sketch, neat by the way! Two low level returns make sense to circulate warmed water but to high level suctions either side of the skimmer do not? They to should be returns but directing water towards the skimmer which I would put on the long side above the low level returns then you create a rolling action in the water which is the most efficient.
Sika and Everbuild are the same company. I guess things have moved on since I last did this so see what you can find out. Laticrete is another really good waterproofer, they set up an office in London dont know if they are still around post covid?

[richie967]

Yes both of the finishes are specialist applied. The Ecofinish is something I nearly bought into but the gun costs a fortune so best left to guys who do it all the time but like polyurea its really quick to apply. Look for polyurea companies outside of the pool industry as the pool industry charge far more than say the roofing companies.

Your original description of your inlets and outlets was why I questioned you but looking at your sketch, neat by the way! Two low level returns make sense to circulate warmed water but to high level suctions either side of the skimmer do not? They to should be returns but directing water towards the skimmer which I would put on the long side above the low level returns then you create a rolling action in the water which is the most efficient.
Sika and Everbuild are the same company. I guess things have moved on since I last did this so see what you can find out. Laticrete is another really good waterproofer, they set up an office in London dont know if they are still around post covid?

I've had a quote for £5k for polyurea, from a farming and welding company. It looks like great stuff, but that's over half my budget, so regrettably it looks like i'll be going with epoxy, unless of course the custom fit bag liner with steps comes in around £1k.

I've updated my model to show the plumbing hopefully how you've described! Unsure how to post images so hopefully you can see that! Here's the link to the image, maybe this will work! https://i.ibb.co/ZmV7bNq/plumbing.png

Kind Regards, Rich

[Teapot1]

Hi Rich, the higher level returns should be on the opposite wall to the low level returns to create the rolling motion I described previously and I would put the skimmer on the same long side as the deep returns so the high levels returns are pushing towards the skimmer.

[richie967]

Hi Rich, the higher level returns should be on the opposite wall to the low level returns to create the rolling motion I described previously and I would put the skimmer on the same long side as the deep returns so the high levels returns are pushing towards the skimmer.

Understood... So like this https://i.ibb.co/vv6j76N/plumbing2.png - You have indeed told me what I didn't want to hear

I was hoping to get away with the same configuration as I did on my last pool. where I only had pipes in and out on one long wall and one short wall! It was only 5 x 3, as opposed to 3.5 x 6.5... So Im guessing as this one is bigger, it needs to be done a bit more industry standard!

[Teapot1]

Hahaha sorry to do that to you but its the best configuration but it is not industry standard, the industry is way behind the science! This rolling design is the result of computer fluidics design, first from colleagues abroard and then separate research by me and a brilliant young university chap who mastered the software. Just sharing it, its how I will be laying out my own pool with the refurbishment. Tested with surface mounted pipes and its good.

[richie967]

Hahaha sorry to do that to you but its the best configuration but it is not industry standard, the industry is way behind the science! This rolling design is the result of computer fluidics design, first from colleagues abroard and then separate research by me and a brilliant young university chap who mastered the software. Just sharing it, its how I will be laying out my own pool with the refurbishment. Tested with surface mounted pipes and its good.

Thanks for the note, also good to be ahead of the curve. So the position of the pipes is done. Now I just need to spend about two years tying all this steel together!

Some more nice images showing the steelwork i've got planned

https://ibb.co/g374FrQ
https://ibb.co/QJQqgZT

[Teapot1]

Buy yourself a rebar wire twister.
QWORK® Automatic Rebar Tie Wire Twister, Pull Tie Wire Twister for Wires and Rebar Ties with Curved and Straight Hook, 2 Pack (10-1/2”, 10-3/4”) https://amzn.eu/d/6EcOht5

[richie967]

Good Afternoon Forum,

A quick update, the pool build is going well, the steel is now tied in two layer son the base along with the L bars ready for concrete. That was fun, and thanks for the tool tie twister recommendation. It worked a treat!

I am just finalising the position of the pressure returns into the pool. And working out how best to achieve the rolling motion that has been described. I don't have main drains. And at present, the only suction from the pool will be the skimmer...But with 4 returns at opposite ends of the pool in an attempt to push water towards the Skimmer. As seen in this image. https://i.ibb.co/C09kp8F/Plumbing-3.png (Can't seem to show images in the post for some reason!) I need to position the Skimmer on the short wall as that's the side of the pool that faces the prevailing wind.

Questions around the plumbing:
1. Will the desired rolling motion be achievable with the 2 sets of return jets at opposite ends of the pool, around 6.5m away from eachother?
2. Should I also include a few low level suction points, and if so, where might be the best place to locate them?

Separate question
3. I am still trying to work out how to level the concrete once its been pumped into the base. I was planning on running a screed bar down the timber frame that I've built to contain the concrete in the base, however the L bars are now obstructing me from doing this! Pic for reference of current pool state! https://ibb.co/yPGZZwm.

I'll be going with the 50mm PVC-U pipe and Hayward Wide Mouth Skimmer .

Cheers, rich

[richie967]

Hi Forum, just Bumping my post!