Insulated Concrete Formwork Building Systems

sas

I've been on site with Euromac and Polarwall. I like the system, its fast and simple.

However, I was strongly warned on boards (by Mellor or Muffler I think) that using any system that doesn't have an IAB\NSAI certificate is a big risk. Hence I had limited my research on alternative systems to Kingspan TEK and Poroton Blocks.

None of the ICF systems in this country are certified AFAIK.

Also, 3 of the local architectural technicians I approached were not willing to sign off on ICF builds.

I have also heard horror stories about the external render systems failing e.g simply detaching themselves from the polystyrene external surface and the entire job having to be redone.

One other thing that turned me off is the complexity involved in cladding such a system in stone. Its doable but its just another variable.

Someone else mentioned a risk of the concrete sweating. However, I hadn't time to discuss this with them so I'm not aware of the details. Possibly a risk of interstitial condensation?

What makes people use it anyway?

Mellor

sas wrote:

Q. What makes people use it anyway?



Ans. I like the system, its fast and simple.

Thats pretty much it. It very quick to work with. I have heard of alot of situations were an issue due the lack of certification. Its still very new, and atm I would rather work with a system that I knew more about (trad, timber frame). But it may be an excellant system, I like to learn more/hear about it in practice. One thing I dislike about it (and this relates to only one manufacturer afaik), they try to sell it as enviromentally friendly construction. I questioned this as its polystyrene and concrete, not very good materials. The reply I recieved, was because "the builder uses less energy when putting it in place compared to blocks". Slightly twisting low energy around there imo.

ardara1

An agrement cert is meaningless - testing on a product in lab conditions - what happens on site is totally different whether its ICF or timber frame or block work.

Main advantage in ICF is the airtightness achieved - nothing much different when it comes to U-values - same results, thermal and airtightness can be achieved using traditional methods - if built properly.

New methods of construction have a risk - there are apartment block being built in Dublin where the acrylic rendering guarantee lapses before the mortgae is paid (warranty of 15 years?)

kadman

http://www.m2ireland.com/

IAB certified.

kadman

sas

ardara1 wrote:

Main advantage in ICF is the airtightness achieved - nothing much different when it comes to U-values - same results, thermal and airtightness can be achieved using traditional methods - if built properly.

Polarwall claim to be able to achieve a U-value of 0.15.

How would you achieve this using traditional methods? I assume we're talking about cavity wall construction. I also assume we're talking about materials that are readily available in this country.

SAS

ardara1

Lets take it from the other direction - how to Polarwall come up with 0.15 W/m2K?

- then lets look at alternatives

I have built a bungalow using an ICF system, the main things that attracted me to it were:

Ease of construction, I was able to erect the structure myself.

Air-tightness. with poured concrete it is unlikely that there will be any air leakage through the wall.

High level of insulation easily achieved without any cold bridges.

The system I used was supplied by "eurozone" I think that they have abandoned the self build market now, to concentrate on commercial & social housing sector.

One feature of their system is that unlike many other systems is that there is a steel structure that the sheets of polystyrene are attached to.

This results in a potential cold bridge, but when I calculated it the loss was relatively small, the U value was 0.19 up from 0.18 without the cold bridging. The advantage of this it that I an able to securely attach battens to the inside face of the walls for fermacell dry lining & to securely fix expanded metal to the external wall before plastering (not done this yet)

Viking house and others believe that thermal mass is important, ICF systems (that have a central concrete core) have a very low thermal mass in this respect, it will perform in a similar way as a timber frame house. It would be quick to heat & quick to cool down after the heating is turned off.

In my house the ICF is asymmetrical, the inside leaf is 50mm & the outside leaf is 150mm, this means that the concrete core can partially act as a buffer zone between the warm air inside & the cold air outside.

For example if the outside temperature is 0C inside is 20C the concrete core will sit at 15C, if the heating was turned off, the inside temperature will not fall below 15C in the short term.
Also with 400mm of insulation & 200mm in the floor below 150mm concrete slab incorporating UFH, I believe that the house will be easy to keep warm.


Will let you know next year if this right or not

sas

ardara1 wrote:

Lets take it from the other direction - how to Polarwall come up with 0.15 W/m2K?

- then lets look at alternatives

You not going to make this easy are you

I have no idea where they get their figures. Lets say I want to achieve as low a U-Value as possible for the external walls using traditional methods. How close to an actual 0.15 do you think you could go and how?

sas

Deleted User wrote:

Will let you know next year if this right or not[/SIZE][/FONT]

Considering the lengths you've gone to (have visited your blog several times over the last few months) I hope you do achieve what you set out to.

Where exactly did you acquire all various the skills required to complete so much of the work yourself?

ardara1

Polarwall use Extruded EPS - same as Styrofoam/polyfoam with a thermal conductivity of arounf 0.30 -

Taking a central core of say 150mm of concrete, it would take a total of 190mm of insulation - 4 " core either side which is total viable - but doesn't account fo rany thermal bridging by any other materials - I believe that they have plastic trays between there panels - Perhaps they do not have to be accounted for.

Traditional cavity 80mm Kingspan/Xtratherm and 50mm internal dryling will achieve 0.15.

Or 140mm Timber frame with HD fibre and Kingspan on the cavity of 50mm - (Service void on the inner skin for services keeping airtightness robust)

Mainly self study thh. & asking lots of silly questions, looking at the achievements (& mistakes) of others. I started to plan this house build about ten years ago. Even at this stage things have changed substantially since I started.

Would I do things differently next time? - maybe...

ardara1

ardara1 wrote:

Polarwall use Extruded EPS - same as Styrofoam/polyfoam with a thermal conductivity of arounf 0.30 -

Taking a central core of say 150mm of concrete, it would take a total of 190mm of insulation - 4 " core either side which is total viable - but doesn't account fo rany thermal bridging by any other materials - I believe that they have plastic trays between there panels - Perhaps they do not have to be accounted for.

Those plastic trays are only about 2-3mm thick so will only have a tiny effect on the U value.

Some ICF systems use moulded blocks that have no thermal bridging at all BECO/Styrostone for example.

ardara1 wrote:

Traditional cavity 80mm Kingspan/Xtratherm and 50mm internal dryling will achieve 0.15.

Or 140mm Timber frame with HD fibre and Kingspan on the cavity of 50mm - (Service void on the inner skin for services keeping airtightness robust)

viking house also promotes a system that will easily achieve 0.15 using external insulation cladding.

sas

ardara1 wrote:

Polarwall use Extruded EPS - same as Styrofoam/polyfoam with a thermal conductivity of arounf 0.30 -

Taking a central core of say 150mm of concrete, it would take a total of 190mm of insulation - 4 " core either side which is total viable - but doesn't account fo rany thermal bridging by any other materials - I believe that they have plastic trays between there panels - Perhaps they do not have to be accounted for.

They gave me a sample from the house I visited of the external eps insulation. It was 6 inches wide ( I just measured it) and the internal eps sheet is 2 inches wide so that gives the required 8". There are plastic rails between each vertical sheet linked across the core by plastic ties which were pretty substantial. Was an exceptionally neat job I'll have to admit, not that that means a whole lot. I saw it just prior to the first concrete pour.

ardara1 wrote:

Traditional cavity 80mm Kingspan/Xtratherm and 50mm internal dryling will achieve 0.15.

Or 140mm Timber frame with HD fibre and Kingspan on the cavity of 50mm - (Service void on the inner skin for services keeping airtightness robust)

Does the first option account for the breaks in the drylining at junctions between internal and external walls?

sas

Deleted User wrote:

viking house also promotes a system that will easily achieve 0.15 using external insulation cladding.

Thats the poroton + external insulation system I think you're talking about.

I'm looking into the poroton block that can by itself achieve 0.18. Awaiting quote from FBT. Big advantage it has for me is the decrement delay and the thermal mass (assuming the marketing material is all above board). Big disadvantage is the cost of it. Blocks are close to 7 euro each and there are 16 of them per sq metre.

When I first looked at polarwall they only had the 50mm inside & outside polystyrene, and the price I was quoted was too high.

Their current range looks much better.

sas

sas wrote:

Blocks are close to 7 euro each and there are 16 of them per sq metre.

:eek:

cheaper to just build with dense concrete blocks and then clad externally.

Mellor

sas wrote:

You not going to make this easy are you

I have no idea where they get their figures. Lets say I want to achieve as low a U-Value as possible for the external walls using traditional methods. How close to an actual 0.15 do you think you could go and how?

Its possible to get to 0.10 with tradition method. Its not easy but possible.

BEDZed, a ultra low energy housing scheme in the UK do it. They have won plenty awards for many of their idea, and use. It incorporates CHP units, wind units on every house, rainwater collectors, solar panals, solar gain design & orientation, combines living working units to cut down on travel, facilities in walking distance.
BEDZed homes are built with cavity comstruction. Its much larger than your standard 300mm. But it is a twin leaf wall withinsulation inbetween. It has a U-Value of 0.10 KW/m2k




Could somebody post a link to (or describe) external wall junctions on ICF.
Mainly, ext.wall/foundation, ext.wall/floor, thanks

Mellor

Deleted User wrote:

Viking house and others believe that thermal mass is important, ICF systems (that have a central concrete core) have a very low thermal mass in this respect, it will perform in a similar way as a timber frame house. It would be quick to heat & quick to cool down after the heating is turned off.
Would that not be a bad thing??

In my house the ICF is asymmetrical, the inside leaf is 50mm & the outside leaf is 150mm, this means that the concrete core can partially act as a buffer zone between the warm air inside & the cold air outside.

For example if the outside temperature is 0C inside is 20C the concrete core will sit at 15C, if the heating was turned off, the inside temperature will not fall below 15C in the short term.
The heat passing through the concrete keeps it at 15 degrees. When the heat is turned off, the concrete will drop too. This will preform the same as a conc wall, the polystyrene keeps heat in, not the concrete, which allows heat through very quickly

I really would like to know more about ICF, as it appears very "site ready".
Do you have a source of domestic details??

Mellor

I used ICF for the rising walls as well, doing it this way I eliminated cold bridging at the floor/external wall

My selfbuild diary

http://dolanbaker.info/index.php?option=com_content&task=view&id=17&Itemid=29

and

http://dolanbaker.info/SelfbuildDiaryphotos/index2.html

should answer any questions,

Mellor

I thought you might have to use it on rising walls too. Does it just sit on the strip, and the 1m or so distance is too long for heat to travel, well some will but for any real effect.

How does it hold first floor?


EDIT: Yours doesn't as its a bungalow.


Looked through the pics, nice work, how was the fermacell to work with? Is the finish on it good.

Mellor

Mellor wrote:

The heat passing through the concrete keeps it at 15 degrees. When the heat is turned off, the concrete will drop too. This will preform the same as a conc wall, the polystyrene keeps heat in, not the concrete, which allows heat through very quickly

Yes that's true but the heat will be lost to the inside rather than the outside from the conc wall, it just means that the temperature inside will be fairly stable.

The house is still under construction but here ia a graph of inside temperature vs outside, note that the house is unheated & there is NO loft insulation at the moment.
http://dolanbaker.info/weather/vws1771.jpg

Mellor wrote:

I really would like to know more about ICF, as it appears very "site ready".
Do you have a source of domestic details??

I used "Eurozone building systems" in co Carlow, (dont have their address to hand will update this page in a few days)

Mellor

Mellor wrote:

I thought you might have to use it on rising walls too. Does it just sit on the strip, and the 1m or so distance is too long for heat to travel, well some will but for any real effect.

How does it hold first floor?

Yes it just sits on the strip, at first floor level (I'm just building a bungalow, so a bit vague here) the floors are normally precast concrete or poured in situ, the ICF has the inner leaf cut away to allow the concrete to form a continous structure, steel bars & mesh are continued into the void between the sheets & tied into the vertical reinforcement, the external leaf remaind intact.the first floor is continued from there.

It would be quick to heat & quick to cool down after the heating is turned off.
Would that not be a bad thing??

I like the idea of the house "riding out" rapid flucturations in external temperature, four seasons in a day Irish weather!

Mellor

dolannaker wrote:

Yes that's true but the heat will be lost to the inside rather than the outside from the conc wall, it just means that the temperature inside will be fairly stable.

Afraid not. The heat will always travel to the cold side. No matter where the insulation is. When heat is off, room cools as it loses heat to the wal, which loses heat to the outside. The wall will never lose heat to the room (except if its hot outside and AC is on, but doesn't apply here)

Deleted User wrote:

I like the idea of the house "riding out" rapid flucturations in external temperature, four seasons in a day Irish weather!

I'm not sure about this one. But materials that heat and cool quickly with vary more with rapid temp changes.

Yes that's true. (must read b4 posting) but the U value between the inner wall and the concrete is 3 times the U value between the concrete and the outer wall. It's all down to temperature differences.

The concrete will always be at a temperature approximately 75% of the difference between the inside & outside values. This and the 150mm concrete floor will (hopefully) stabilize the internal temperature.

Mellor

Mellor wrote:

Looked through the pics, nice work, how was the fermacell to work with? Is the finish on it good.

Heavy! but very strong, I used a pnumatic nailer when fitting the sheets, the edges of each sheet was glued to its neighbour, this makes for a very solid wall. I then applied a 'skim' coat of "fine surface treatment" it's a bit like gypsum plaster but is formulated for fermacell the surface looks as good as skimmed plaster.
My wife is painting the walls this week, I will update the website with some pictures soon.

PS for the ceilings I cut the boards in half before fitting, I felt like popeye when I finished that job

sas

Mellor wrote:

I thought you might have to use it on rising walls too. Does it just sit on the strip, and the 1m or so distance is too long for heat to travel, well some will but for any real effect.
QUOTE]

The house I visited with Polarwall was designed and being overseen by www.mosart.ie.

The had built the rising walls as standard and poured the floor slab. The ICF walls sat on the rising walls, much like timber frames I think.

What polarwall had recommended was that they put the floor insulation on top of the floor slab thereby overlapping with the internal insulated face of the ICF wall.

There is alot of details on how their system ties together at http://www.polarwall.co.uk/Specification.html
Also the BRE cert is at http://www.redbooklive.com/pdf/111-04.pdf. What did sort of annoy me when talking to them is that they push the fact that it has BRE certification. But from my reading of it the certification is for when the entire ICF wall is treated as the inner leaf of a cavity wall construction. It doesn't cover the most common situation in this country where the external face of the ICF wall is rendered. They didn't mention this.

sas

Deleted User wrote:

:eek:

cheaper to just build with dense concrete blocks and then clad externally.

If you mean to clad with external insulation then that isn't a whole lot better. Prices for that run from 70 - 100 euro (+ VAT) per square metre from what I've seen. Also its a non runner for stone cladding of which we do have some.

It doesn't have any certification either in which case I'd most likely opt for ICF.

ICF is definitely one of the cheapest ways of getting low U-Values.

Viking House

sas wrote:

ICF is definitely one of the cheapest ways of getting low U-Values.

I only just found this Construction forum, it seems you guys have been using it for a while.
U-value is important but the density of the insulation you are using is equally important. A more important figure I think we should be using is the temperature fluctuation of the house when the heating is off.
I was in a house in Holland at Christmas that had a temperature fluctuation of 4 degrees and was insulated to 0.25 U-value with woodfibre insulation (250kgs/m2).
I was in a Passive house before Christmas insulated to 0.15 with fibreglass (20kg/m2) that had a temperature fluctuation of 8 degrees.

Mellor

Don't worrk VH. You didn't miss anything. The forum is new, they just moved all the relevant threads from Gardening accross. This forum is only a few weeks old

Viking House

Viking House wrote:

U-value is important but the density of the insulation you are using is equally important. A more important figure I think we should be using is the temperature fluctuation of the house when the heating is off.
.

Yes, this is a very important aspect of energy conservation, I am actively monitoring the internal & external temperatures of my new build see here it will be interesting to see how my house performs next winter.
Note that the loft insulation is not yet in place

Viking House

Yes! but Polysterene is one of the least dense insulation materials there is, so if you turn off the heat on a cold day the house will get cold quite quickly. Polysterene is made up of closed bubbles that won't leave heated air into the insulation so it can't leave the heat back out when the heat is turned off.
People talk about the thermal mass of concrete, concrete leaves off its heat in about 3 hours.

If you bring a concrete block into your heated living room for three days you will still get a cold arse when you sit on the block on the third day.
Its what they call cold material in Scandinavia and the feeling of cold you get when you stand close to a concrete wall even though the temperature is the same near the wall as the middle of the room.

In order to put some density into ICF to reduce dramatic heatloss and to avoid fungus and mould problems I would consider lining the inside of the house with 50mm softboard and then Plasterboard or Fermacell.

kadman

It is possible to order varying densities and thicknesses of some ICF manufacturers polystyrene products, as there are double panel systems , and single panel systems available. Whereby the double panel wall effectively acts as both a polystyrene formwork with a core fill of concrete, and a structural render on the 2 cores of polystyrene. And the single panel polystyrene being coated on the 2 faces, internal and external, with a structural render. Thes single panel can be manufacured as thick as 330 mm polystyrene, with 35 mm structural render. Double panel 100mm polystyrene, 150+ core fill, 10mm polystyrene.

kadman

Do-more

Is there much benefit in using aerated concrete to fill the ICF's?

Come to think of it, is there anyone pumping aerated concrete in this country?

Viking House

ardara1 wrote:

Main advantage in ICF is the airtightness achieved - nothing much different when it comes to U-values - same results, thermal and airtightness can be achieved using traditional methods - if built properly.

When has the traditional method ever been done properly? Irish blocks are made with a tolerance of +- 1mm so any 2 blocks in a pallet can have a 2mm difference between them. Thermal Looping occurs when there is 1mm between the insulation and the block reducing the effect of the insulation by 33% on average!

Have you ever seen an Airtightness test result for a traditional Irish built house?

ardara1

Viking House wrote:

When has the traditional method ever been done properly? Irish blocks are made with a tolerance of +- 1mm so any 2 blocks in a pallet can have a 2mm difference between them. Thermal Looping occurs when there is 1mm between the insulation and the block reducing the effect of the insulation by 33% on average!

Have you ever seen an Airtightness test result for a traditional Irish built house?

I've carried out 4 over this pas 2 months - on houses where the builder had not been notified as to what the test was about - we averaged 6 - just about twice as good as the standards asked for under Part L. (All house were were wet finished internally) We've also tested Timber frame and had results of 5 (And 12 - bad one!)

I'm confident that wth a bit more care on site air permeability can achieve below 5 (or 0.25 achr) quite easily)

Do-more

Do-more wrote:

Is there much benefit in using aerated concrete to fill the ICF's?

The only benefit I can think of is a marginally better U value of the completed structure.
May be OK for non-loadbearing parts of the structure, But you would need to use ordinary concrete over lintels etc, probably more trouble than it's worth.