FM2015

No substitute for experience. Experience reduces risk. Cost per performance is on par if not superior. Sounds like you got snagged on a labour only contract thinking it would be cheaper. Multi unit developments work out cheaper again. Biggest problem with ICF and mass build? We'd make thousands of brickies jobless.

And rebar quantities are proportional to design of the build. Plenty of engineers will specify lintel steel only; irrespective of ICF product. 3.5 times stronger than a concrete block without joins.

Be fascinated to see the actual details to deliver 200+M2 shell for less than 12k. Take out pumps and 2nd man and I'm down to 7k. Probably 20m3 concrete, another £2000 based in a 4" cavity. Ancillaries, bracing, scaffolding, poleplates, ledger system, another £1k? So the product cost £4,000, £20/m2. Which less than 50% the cost of nearly all other ICF systems. 20/M2 barely covers the cost of the pir board in woodcrete. You've then got air tightness to achieve on the walls. £12k is so cheap I think it needs a good deal of clarification so that it is useful as a reference. £60 only just gets you a square m of decent ICF without concrete.

I heard about sika......it's site and setting specific and, reading between the lines, depends on the ICF being used and who is installing it. Sika, like others seem to like selling you every in the catalogue! No brand bentonite works well but needs total protection until filled. Physical step and properly pokered concrete is all you really need most mass poured ICFs everything else is just a failsafe

Not essential. Depends on warranty provider, architect, design etc. Tend to stay away from to the waterbars that swell. You need a dry day to install and then want keeping dry until covered with concrete. Sika do a physical stop. More practicable. Get your outside done right and nothing else should be tested. Waterproof concrete is a waste of money. Something outside and something maintainable inside gives lowest cost option and satisfies most conditions.

Pound for pound an uninsulated slab/raft and a high performance wall will give you more benefit than an insulated raft and high performing walls. A correct sap assessment using supplier details rather than standard shows u values of walls isn't the be all and end all and a normal raft can be protected to afford some of the insulated raft benefits. Based on experience from 40+ units of various designs.

@ZacP This still requiring more information? Thought I would add our two peneth...... Supply & install of an EPS, pre made(no on site assembly) ICF £100-£200/M2. The closer to a four sided single storey box, the closer to £100. Probably works out at a labour only rate of £34/M2. At that rate, price through the windows. Covers labour and ancillary materials. Includes, bracing, pump, equipment hire. Basically everything. The time is actually less important. You might, and a lot do, think that a quick job is a less expensive job. It's quick because we're experienced. It's not cheap because the end product is higher quality (generally speaking) than any alternatives. And we're experienced. 60 person hours to get a bungalow from slab to wall plate, with two gables, poured and then stripped out. 68 linear metre and about 190m2 of wall. You might get someone in to work for day rate or £20/h and a total of £1200 labour sounds like a dream. We'd have to do 1000+ units per year just to pay our insurance premiums on those rates. And then you have all the capital expenditure, training, H&S, tool provision, alignment systems etc etc. So at 40/M2, your looking at £10,400, or supplied and fitted a minimum of £26,000. You can also find people who will come and pour it for you after you've done the donkey work. Our insurance doesn't cover us for that, we pour our own work with full backing or someone else's with no backing. We can't guarantee someone elses work in the same way a sparks or plumber can't. I've just scanned what I've written and hear the groans already. But experience, especially regarding H&S, means we can't be cheap. I'm not sure most self builders realise that if you get someone in on day rate to help out, the self builder is liable for the HSE requirements. And should something go wrong, your dream home will become a nightmare. And what could possibly go wrong with inexperienced people pouring 60t of concrete into a non solid formwork?!? And to the groaners, you're right, it probably won't happen to you. Be thankful, not condescending. If the HSE get you, it'll be 4 years of grief for a paper cut. Rant over. Thanks, good therapy session!

It won't be anything to do with nudura. You can't ask Celcon to be responsible for a block layer.

Good idea, a box would also work. We had to be super specific to tie in to an isokern pumice DM system and followed the plans only to find that architect and hetas don't agree. Our 4kw stove "needs" twin wall through the wall. Installer not happy with a sleeve, of say, size above single wall flue. So our hole is closer to 600 high. At what point does it become a window needing specific reinforcement? Personally, it's an area of regs that suffers from only affecting a very small number of builds. Not enough examples to create a single accepted method. Interestingly, a number of ICFs get their firerating when fixing plasterboard directly to EPS. If you batten it off, you can't get the fire rating. The void acts as a chimney.....then Grenfell happened. So hidden voids should be designed out of internal surfaces. Hetas recommend a board product for behind stoves that needs standing off the background. Contradictory? Confused? The manufacturers should be working harder in these areas.

Currently got just this issue on one of our builds. Are you planning on twin walling everything from "pot" to stove? If yes, hetas are apparently happy with 50mm of clearance to anything combustible....this also include plasterboard....the paper is flammable. Sleeve needs to be a maximum of 45 from vertical. If you are pre pour, a sleeve with at least 50mm larger diameter than twinwall is ideal. We have had differing views of what protection the EPS needs behind and around the actual stove. Current job has a 4kw stove in a room with no fireplace, it's just in the corner. If you have a fireplace, it's a bit easier to make tidy. Ours is a nightmare. Remember, no void space is of paramount importance. So, either agree a build up directly onto EPS or take the EPS off back to the concrete. Speak with hetas as they offer good advice and give you something to approach the installer with. Dom

If you can separate the non EPS component, I know a guy who puts the EPS component through a garden shredder. Great for insulating some of the hard to reach, enclosed places. All in non dwelling type buildings. I'm not sure what the HSE would think of this!

How much are you producing? We generally waste less than a couple of dumpy bags and never more than a 6yrd skip. A skip is an economical route if you discuss it with the skip firm.....there's good money in EPS. If you're still building, and without knowing anything about your project, I'd say you need to adjust your process to eliminate a greater proportion of the waste. Not exactly the cheapest material to be throwing lots away. What's the system and where are you?

Resin fix post concrete. Simple

@pipedream we see primarily A (proper French drain) and C as the dominant options. Waterproof concrete is a) expensive and b) in most cases has to get wet to work. Therefore if space isn't an issue and cost is a factor, A and C (internal maintainable system for which a supplier will supply a warranty) offers the most effective and cost efficient method of satisfying the largest number of structural warranty providers. One critical factor which is often overlooked but can have an impact is that not all build systems are BBA approved for basements. And the list is being restricted due to issues. From a scientific point of view no A means a real world test for B which then has no secondary defence and is not maintainable. In the age of litigation, a single method of waterproofing doesn't make sense in my book.

Is your ICF and EPS/XPS variety or a woodcrete? Just remember that if you cut into ANYTHING or remove ANYTHING that is there to keep the block whole, brace it afterwards. Take a Nudura block for example, 457 high. You can easy reduce that by 100mm from the top and won't have an issue. Any more, up to 150mm, you might get away with it. More than 150 and you've effectively got a block that has nothing connecting the two sides together at the top. Cue the flaring, bursting mess. If you touch the core structure, the strength must be replaced. Otherwise it's just a former, make it do what you want. Designing houses to the block can be useful, especially if you then get the block by block plan BUT it's very easy to end up a few blocks short. And in my experience, most architects misunderstand something on course one which makes any kind of planning wasted. Plus, you take Nudura again as an example, great if the wall is a multiple of 8" but it won't go squarely into a 8' block, ie it won't be a multiple of 96" so there will always be cutting. It's what experience or diligence does with the off cut that counts.

Ha, been a while since I was a boy scout? and was better at tying knots! I've seen reports on some builds that show thermal inefficiency, ie the outside warming up or being warmed from the inside, allowing some moulds to grow. On all sorts of builds. I've seen it on ICF where expanding foam has been poorly applied to make good a surface prior to render. The EPS and spray foam have different thermal properties and you can see where the foam is due to the darkening of the render due to mould/lichen type things.

It could be that actually it's warmer. Doesn't moss grow on the south side of trees?

Sorry Jack, I totally agree you with regard quality and experience. With regard below ground ICF, warranties are fairly easy to obtain for some ICFs and less so others. As a proponent of ICF in general, I think this should be stressed. Not all ICFs are the same and there's a lot of guff around, surprisingly, a lot of brand Vs brand stuff which is ultimately pointless.

ICF basements and ICF below ground walls need two of the three zones protected. Ideally using different systems and one must be maintainable, pretty much as Bitpipe says. In a lot of cases, waterproof concrete is a waste of money. So external French drain and internal drainage system (maintainable). A waterbar for good measure but the same can be achieved in concrete slab by creating a step. Remember, not all ICFs are the same or have the same structure so their performance below ground differs. Woodcrete along with a number of EPS ICFs: lattice work, polarwall: massive continuous slab. I would also double check to see which ICFs are BBA approved for basements. It's a moving playing field at the moment. Reading some of the comments regarding "not being able to see it once poured" and I can hear the collective concrete world groan. It's really not difficult to do right. I would also be interested to find a timber frame that matches the airtightness of mass poured concrete at the same stage without being wholly reliant on tapes and membranes. Think of a closed box with a window hole in it. Which is going to be easier to guarantee airtightness? A concrete, mass poured box or a timber frame box? You can achieve the same with both but one is easier and involves less processes than the other. Yet to find a TF in 2021 cheaper than an ICF. And I don't expect to. One ICF brand has put its prices up 10%, timber has jumped 40%. Whatever anyone says, and this goes back to my comments on cost management elsewhere, be pathological about comparing like with like and make sure you, as the self builder understand the processes involved in getting, say, a TF and ICF to the same build stage. No one makes it easy. It helps if you've done one of each, next to each other.

Problems befall all builds but water ingress is potentially the most damaging and difficult to solve. With ICFs as well, it is a perfect storm of poor detailing and poor quality installation. And the solutions tabled by some brands are incredible. One would say don't use a check reveal and use illbruk's tapes adding up to £200 per window, plus ICF installer labour (wasn't aware we fit windows) plus your window and their fitting. And it still isn't bomb proof. I'd guess you are fairly exposed where you are, with driven rain? Leaks worse in certain direction? I'm in a similar position with next to nothing between me and Brazil. We might be SW England but that just means it's warmer when the rain is horizontal. We live in an ICF with uPVC windows and slate sills, a combination that often results in leadwork, illbruk's million pound tapes or leaks. Totally not necessary. Don't have anything other than physical doglegs and silicone. No leaks either. Well formed check reveals, cills which extend left and right and a sealant applied to frame before fitting. Cement board on the reveals has become a given down here because the renderers got fed up with people not being able to make a nice opening. The advantage is another physical dog leg for the weather to circumvent. Otherwise, render to a stopbead, silicone the stopbead/window join and happy days. Low cost extras: DPM under cill, forming concrete to shed water outwards, over width cills. It might sound like you're doing a fair portion of the window fitters job but down here they're on £50/window and really don't care that much. Understandably. In your case, would it be possible to remove the cills and replace with wider ones? They shouldn't be fixed to the window. Coincidentally, that's often the number one cause of leaky windows in my ICF experience: low cost windows, fitted averagely, then screwed down through cill. Window leaks then funnels water straight into the wall. Find an old house with wooden windows, chances are, if the frame is sound, the window doesn't leak. No tapes, no lead, no silicone. Just decent geometry and quality workmanship. More than one way to skin a cat too!

If you can get an RSJ that fits within the block, for example a 150 wide beam could fit inside a 6" core block (Nudura forms) and sit on pockets cast in the concrete at either side of the opening. The RSJ can then be packed out and clad with the same ICF. 5m is do-able with concrete but worth it? I'm not sure.

Lots of projects with 75% glass walls until they get a price for the glass! 100m2 of wall of which 20% is opening so meterage rate is multiplied by 90m2 =total area less half the glass. Couldn't really be fairer. Plenty of framers price through openings.

£35 for blocks £20 for concrete £5 for steel £5 for pump Plus labour, scaffold, bracing. £80? Can I have his number please?!

Word on the grapevine is that LABC are trying to stop providing warranties on ICF and some other mmcs. The last set of T's and C's I saw wouldn't allow timber lintels. Finding someone with a relatively local office and experience of the particular MMC eliminates a lot of issues.

I'll stick my neck out.....we undertake projects at rates between £120 and £220/M2 of wall area plus half of the window area. Lots(!) Of factors. The closer to a single storey, 4 cornered, standard windowed box, the closer to £120 you get. Design is the biggest factor and then geography. That covers everything from slab to completed walls and openings. All materials, all equipment all labour to install one particular brand of EPS ICF.