pro's & cons of different ICF systems

[mvincentd]

Hi

 

This ICF section of the forum seems very dormant given that in other sections numerous people have eluded to their build being in ICF.  Clearly there's a predominance of timber frame builders here.  Perhaps we can all come out of the woodwork and identify ourselves to each other?

 

I'm currently leaning towards Nudura as I intend to put it up myself and value the wealth of backup in the form of their training, all the videos, a huge user manual, they're a big company that seem to have evolved the blocks to maximise their practicability.  I also like the large block size to minimise the amount of joints as they're the obvious weak spots during the pour.  I'm not seeing another ICF that has anything 'better' about it, however i've not yet got quotes.....and i'm bracing myself for Nudura to have a bit of a premium (i might be wrong).

 

Is anyone a bit further along in their experience of selecting which ICF?

[le-cerveau]

I will be using the Izadom 2000 Polska system as supplied by Econekt.  The main reason being that as I will not be able to be on site for the build, it will be done by a contractor, I wanted to select the simplest system and this system has both the raft foundation and walling and they interconnect, so one less thermal bridge to worry about.

[Ferdinand]

40 minutes ago, le-cerveau said:

I will be using the Izadom 2000 Polska system as supplied by Econekt.  The main reason being that as I will not be able to be on site for the build, it will be done by a contractor, I wanted to select the simplest system and this system has both the raft foundation and walling and they interconnect, so one less thermal bridge to worry about.

 

That sounds Ed Balls' number for Strictly next week!

[Stones]

I'm using the Amvic system.  The choice of this system is purely down to the fact it is the system used by my builder (and the other ICF contractor working up here).  Whilst  it doesn't have a 'passive slab', all the feedback about running costs that I obtained from people living in houses built with this system led me to the conclusion that it wasn't worth worrying about.  My builder did go down to an awareness session for another system a few months ago, but has yet to make the switch, the main issue being that the premium charged for the time / labour saving differences (passive slab / additional insulation slotting into core) is significantly more than the actual financial savings to the builder / his clients.

[gavztheouch]

I am looking a Nudura as it has the long track record in Canada and its available in Scotland. I have a sample block that im going to have a play with to figure out how to do the windows and lintels, etc. I would be open to looking at other systems, what else is available in the UK?

[RichS]

Ok, I will throw two more names into the hat.

I have been looking at Beco Wallform and also ICF Tech made by the Lichfield group.

At the moment I am favouring the Lichfield system, very good U values!!

Edited November 16, 2016 by RichS

[Vijay]

Have you looked into Polarwall? That's the supplier I'll be using and Alan has been one of the most helpful people I've come across

[Barney12]

44 minutes ago, Vijay said:

Have you looked into Polarwall? That's the supplier I'll be using and Alan has been one of the most helpful people I've come across

 

+1 on Polarwall. When I was researching ICF they were incredibly helpful and really embrace the selfbuild market.

[Alexphd1]

hopefully start the icf part of the build next week ! we picked nudara from the scotish agent.

Edited November 16, 2016 by Alexphd1

[jamiehamy]

Polarwall here - Alan was brilliant to work with and invested a lot of time in helping me with planning and the actual pour. Product was great to work with - realy straight forward and very flexible. 

[mvincentd]

A couple of systems there i'd not yet discovered.  Interesting that rather than a pure technical head to head it very often just comes down to simple practicalities like availability of product & knowledgeable labour....I guess all the systems 'do the job'.

The ICF Tech looks like it has a positive point being UK dimensions...though they're wrong claiming to be the only one; Sunbloc are too.

Having watched a Polarwall site progress I was put off by the complicated mess it looked, plus my build has curves which seems to dictate a real compromise to how it was designed to perform.  That said Alan is enthusiastically helpful and others on my Nudura course had positive experiences with it.

So all in all i'm thinking price might be more influential in my final decision than I expected, with it being easy enough to get to grips with any of the systems.

[RichS]

As usual the more I read the more uncertain I become over which system to use.

I had originally dismissed Polarwall because I didn't think it looked robust enough to do the job. I have worked on some fairly decent sized civil engineering projects and seen 18mm plywood shuttering burst under pressure, but according to all the videos and testimonials Polarwall takes it no problem.

I contacted Alan as the web site wouldn't let me download and he responded very rapidly, which has got to be a good omen. I think I will send him my drawings and see what he comes up with, nothing ventured etc.

[JimG]

Hi,

 

Coming from a position of theoretical knowledge, my wife and I are planning a new build and our current favourite for construction is Durisol (I've read @recoveringacademic's experiences, which seem to be related to the human element, not the product). I like the idea of ICF, but I'm not so keen on the idea of EPS mainly because of securing stuff to it (shelves, bannisters, whatever). Is that really a concern? I've talked to reps about one or two systems and they talk about either drilling right through into the concrete or into the connecting webs, but how can you locate them once the wall is finished? I've also wondered about the heavy-duty plasterboard I've seen somewhere (probably the NSBRC) and wondered if that would be the answer. So I'm open to personal and more practical experiences!

 

My main concern with Durisol, which has been mentioned by recoveringacademic, is getting the right consistency of concrete. Durisol specify the slump, but how do I know what's actually been delivered and whether it's been poured correctly?

 

Then there's Velox, made with similar material to Durisol but in sheets rather than blocks. In theory that should reduce the problem of getting the right consistency of concrete, but in practise it seems to be used even less than Durisol in this country which means that there may be a problem with getting people to use it correctly. Apart from that Velox "isn't from round these parts" (I think it's from Austria) and it doesn't have BBA approval - it does have European approval which the importers say must be accepted as equivalent, but our architect is concerned that it might be an uphill struggle to get Building Control to agree.

 

Over to you!

 

Jim

[najem-icf]

Up until recently, Durisol refused to be classified as an ICF and have only now jumped on the bandwagon by calling themselves the "first ICF" on the market.  They are right in what they claim, however the application at inception was for use in non-habitable spaces like garden retaining walls etc.  Personally, I have a number of issues with Durisol - firstly, they are not members of the ICFA, which means they are not accountable to anyone but themselves - that is evident from the posts you have read on here.  My second issue is that you have a continuous material that features from the outside world to the inside world - in other words - a cold bridge.  Third, they use foil faced PIR/PUR boards to "beef up" the uValue of the wall - however they pay no attention to the fact that every single PUR/PIR manufacturers BBA (or ETA) cert states that there must be a barrier between the concrete and the foil face.  I have yet to see a Durisol build where the foil is actively protected.  In essence, the concrete burns the foil and renders the board much less effective.  Fourth, it is marketed as the only "permeable ICF block on the market" - in a day and age where air tightness is the aim, that should not be a selling point.  Reminds me of an article I read when I was Stateside some years ago about a Durisol build 22 storey hotel in Canada - built back in the early 1980's - guests complained of "ghosts" in the rooms - later realised it was curtains moving due to air penetration through the structure.

 

Then there was this article that summed it up for me - http://www.telegraph.co.uk/news/2017/09/01/grand-designs-dream-home-ruined-biblical-plague-moths - anything organic will eventually attract vermin.

EPS based ICF's will either have a plastic or metal strip that serves two purposes - one is to provide EPS something to adhere to during the manufacturing process, second is to provide a fixing point for the next phase of construction.  I know one manufacturer in particular has done extensive testing on pull out strengths of various screws into the ABS plastic strips - a standard drywall screw has a pullout strength of 95kg and a permissible load of 24kg per screw - the highest proportions were 130kg pull out and 41kg permissible.  If you are still concerned, you are only 70mm or so away from concrete - in one case I recall using Simpson ICF-LC brackets cast into the ICF wall and attaching a timber runner to which you can fix anything heavy.

 

These webs are factory manufactured, so will feature in regular intervals.  If, for example, they are at 200mm c/c, you can measure from any corner and know you will hit a web consistently at 200mm c/c's.  Most (if not all) EPS based ICF's have markings on them to indicate where the webs are.  I have attached photographs of various EPS ICF's to demonstrate this.

 

I do agree with your architect - while ETA's should be accepted Europewide, there is always a comfort and preference of Building Control to accept BBA/BRE/LABC etc as they are familiar with the formats.  ETA's are also somewhat deceptive - I came across an ETA for an ICF that simply confirmed its use as a permanent shutter - no testing done on its thermal properties or fire resistance etc - not to mention that the product has a completely different name in the UK to what the ETA is for.

 

Something else to consider would be the ease of getting mortgages - I often hear people saying they don't need a mortgage and are building using their savings - these are forever homes that they intend to grow old in.   Nice thought - however - what happens when eventually the property is left to children/ next of kin?  They are unable to sell it because people cannot get a mortgage (or the Loan to value is miniscule) and they will end up with a massive inheritance tax headache.  So whatever you chose - make sure there is plenty of faith and support behind the block.  ICFA membership is a good start (www.icfa.org.uk) and secondly, ask the suppliers what the highest building they have built in the last 12 months was - seems silly - but the reasoning behind it is simple.  Whoever decided to take the risk and build a tall building will have done so after seeking assurances from engineers, architects, insurers, lenders, QS's etc - it would not have been a decision taken lightly on the flip of a coin.

 

Hope this helps

Edited September 14, 2017 by najem-icf

[ToughButterCup]

10 hours ago, JimG said:

[...]

My main concern with Durisol, which has been mentioned by recoveringacademic, is getting the right consistency of concrete. Durisol specify the slump, but how do I know what's actually been delivered and whether it's been poured correctly?

[...]

 

A legitimate and sensible concern.

The company do a training course. It addresses all those concerns. Briefly, you use one of those mix-on site set ups  like (locally) this company.

 

Its our final pour today, I'll see if I can remember to take some detailed photos and post them on this thread.

 

[PeterW]

7 minutes ago, recoveringacademic said:

 

A legitimate and sensible concern.

The company do a training course. It addresses all those concerns. Briefly, you use one of those mix-on site set ups  like (locally) this company.

 

Its our final pour today, I'll see if I can remember to take some detailed photos and post them on this thread.

 

 

Did they come through good for you @recoveringacademic..??

[jack]

Interesting stuff, thanks @najem-icf

 

8 hours ago, najem-icf said:

Then there was this article that summed it up for me - http://www.telegraph.co.uk/news/2017/09/01/grand-designs-dream-home-ruined-biblical-plague-moths - anything organic will eventually attract vermin.

 

To be fair, I don't think cement-impregnated wood is anywhere near as attractive to vermin as the sheepswool in that article.

 

8 hours ago, najem-icf said:

My second issue is that you have a continuous material that features from the outside world to the inside world - in other words - a cold bridge.  

 

What's the U-value of the block material itself? It looks like there's quite a bit of air captured in the shredded wood, which I imagine means it has a U-value that's quite a bit lower than concrete. If that's true, then it's less a case of cold-bridging, and more a case of warm-bridging! Not sure whether that makes any difference to the assessment, but it feels like it'd be less likely to cause a problem than true cold bridging. Thoughts?

 

8 hours ago, najem-icf said:

Third, they use foil faced PIR/PUR boards to "beef up" the uValue of the wall - however they pay no attention to the fact that every single PUR/PIR manufacturers BBA (or ETA) cert states that there must be a barrier between the concrete and the foil face.  I have yet to see a Durisol build where the foil is actively protected.  In essence, the concrete burns the foil and renders the board much less effective.  

 

As you referring to the internal PIR/PUR or a separate later added afterwards? If the former, as I understand it, if there's no gap between the foil and the next surface, the foil contributes nothing to the insulation value anyway, since it can no longer reflect radiated heat. Heat will instead move by conduction due to contact. In that case, it's irrelevant whether the foil is intact. 

 

 

[Jeremy Harris]

The level of false information floating around about the foil on insulation board needs addressing.  There isn't an issue with pouring concrete on foil faced insulation.  Yes, the alkaline nature of the wet concrete might, possibly, cause some oxidation of the foil surface, but, as @jack has said, the foil isn't serving a useful function in this application anyway, other than at temporary protection for the insulation, so this is irrelevant.

 

The foil, or often silver coloured paper, facing on some forms of rigid insulation is there for a few reasons.  It makes the material easier to handle in the final stages of manufacture, transport and handling on site, and it provides a partially effective radiant barrier when exposed to an air gap, where it can reflect back some of the long wavelength IR and so help to reduce surface heating of the insulation from heat radiating on to it.  This latter property can be useful in wall or roof construction, where reflecting back out excessive secondary solar radiation can help to improve the short decrement delay factor that all low heat capacity insulation materials have.

 

 

Edited September 15, 2017 by JSHarris

[jamiehamy]

@JimG. Regarding securing things to icf walls, we opted for battens inside to which plasterboard is then afixed. This gives us the option of fixing to the. Plasterboard or if additional strength needed, to the battens (placing additional ones where needed). 

 

For Polarwall, there are plastic rails every 300centers vertically that are pretty robust and can be screwed into. 

 

 

[Bitpipe]

Before we went down the timber frame route we considered doing basement and house in ICF, however for our design it proved more expensive than a traditional shutter pour basement and TF house on top.

 

We did look into these guys quite deeply and visited a very impressive build they had done - interesting system in that it has floor and roof elements as part of the system.

 

http://thermohouse.co.uk/passive-house/

[Jeremy Harris]

I also considered ICF back when we were trying to buy a plot where a house built in to the hillside would have been the only option that the planners would consider.  I found back then that the cost difference between ICF and other forms of concrete construction (and the house we were then thinking of really had to be concrete, being partially earth sheltered) wasn't significant, both were much of a muchness.  One thing I ran up against was the potential lack of internal heat capacity, because of the layer of low decrement delay insulation on the inner face of the external walls.  The concrete core is effectively pretty well insulated from the house, and sits at a temperature that is, on average, around the mid-point of the temperature difference between the internal and external air temperatures.  As such it cannot contribute anything useful to improving the internal thermal time constant, as there can never be any inward heat flow from the concrete core to the house when the outside temperature drops, because the concrete core can never get close to the house temperature.

 

This was around the time when I started looking at how decrement delay and the internal thermal time constant was impacted by various construction methods, and back then, had we managed to persuade the chap to sell the land (we didn't) then we were going to go for externally insulated concrete, primarily to avoid the need to have an additional layer of relatively high heat capacity material internally to provide enough thermal buffering.  Part of this was down to the site, though, as we had two and half walls, plus most of the roof, that would have had a fairly constant, all year around, temperature of around 8 deg C, which is an unusual condition and poses some challenges both in winter and summer in terms of internal temperature self-regulation.

[jack]

2 hours ago, jack said:

What's the U-value of the block material itself? It looks like there's quite a bit of air captured in the shredded wood, which I imagine means it has a U-value that's quite a bit lower than concrete. If that's true, then it's less a case of cold-bridging, and more a case of warm-bridging! Not sure whether that makes any difference to the assessment, but it feels like it'd be less likely to cause a problem than true cold bridging. Thoughts?

 

Just had a thought in the car: When i made the comment above I was thinking about the concrete and cement/wood components and neglecting the rigid insulation in each cavity. So yes, there is cold-bridging. The question is whether it's problematic cold-bridging, and to that I don't know the answer.

[ToughButterCup]

29 minutes ago, jack said:

 

Just had a thought in the car: [...]

 

'Keep yer mind on yer driving

Keep yer hands on the wheel,

And keep yer snoopy eyes on the road ahead,

We're having fun

Pumping all the concrete 

And kissin' and a huggin with Fred'

 

Apologies are in order, not sure to whom though

[JimG]

Wow, thanks for such detailed replies @najem-icf, @jack, @JSHarris! Also @jamiehamy.

 

Getting back to attaching things to EPS ICF blocks, I understand the theory of finding a web by measuring; what I'm not so confident about is finding one when I want to put up a shelf in 10 years' time. Measuring from a corner is fine if you know exactly how much offset to allow for plasterboard (or whatever) and if it's the same in every room. If I have to keep maps of every wall I can see it going wrong at some point. The other thing is that assuming I do this, locate a web and screw a fixing to it, how do I know how far from the centre of the web I am? Have I just caught the edge of it, giving enough resistance to feel good but not enough to be strong? Do I worry too much? ;-)

 

Jim 

[jack]

What about putting strips of something over the webs (or maybe every third of fourth web) that will be detectable with a stud-finder? Would aluminium tape work?