DIY ICF Construction - Bracing

[scottishjohn]

6 hours ago, jamiehamy said:

Okay, clearly we're not going to agree on this or come close. 

 

For any icf'ers reading this thread I would suggest being very wary of building icf without bracing even if it's suggested. There are multiple reasons for this, from basic Health and Safety to implications for the subsequent concrete pours. Maybe 4 courses might with stand a strong wind but then you have two concrete pours not one. . And once you add in tons of concrete it's all magically to stay absolutely vertical? Each to their own of course. 

 

 

 

[deleted by mod]

"And how one keeps the walls plumb is beyond me - they are lightweight and have in many cases no inherent stiffness"

to say woodcrete has no stiffness just shows how little you know of it ,

Edited May 28, 2019 by jack
Please try to be polite

[Mr Punter]

6 hours ago, Alexphd1 said:

For the little extra cash I will be using waterproof concrete (with all water bars etc), external tanking and good drainage on a 3 sided basement. As you say it's a major to sort out later!

 

I would not recommend this. With ICF you cannot see voids. You will not be able to see the water bars. Normal concrete is fairly waterproof in any case. If the external tanking is correctly applied and guaranteed it should work without waterproof concrete.

[Russell griffiths]

What I don’t get is with these woodfibre type blocks is this pour strategy, they say you can pour every few courses, if this is the case how are they dealing with dry joints between pours, if you had a 5m high wall and poured it in many pours it’s not exactly a monolithic structure is it. 

???

[Mr Punter]

1 hour ago, Russell griffiths said:

What I don’t get is with these woodfibre type blocks is this pour strategy, they say you can pour every few courses, if this is the case how are they dealing with dry joints between pours, if you had a 5m high wall and poured it in many pours it’s not exactly a monolithic structure is it. 

???

 

Some I have seen where you can spray retarder on the top after pouring then jetwash this off when you are built up ready to do the next pour.  Sounds impractical to me.

[jack]

21 minutes ago, Mr Punter said:

Some I have seen where you can spray retarder on the top after pouring then jetwash this off when you are built up ready to do the next pour.  Sounds impractical to me.

 

Yup. Can you imagine jetwashing down into a deep recess within the blocks? And where's the water/retarder going to drain to? I know there are gaps, but do you really want concrete retarder thrown about all over the insides of your blocks right before you pour?

[scottishjohn]

how many months are you talking about between pours?

,you not going to top of last block anyway ,or polishing up the surface 

there will be plenty of grip between the layers -

not all poly systems are poured at one go either .

i suppose if you want to be belt and braces then drop some re-bar in 

you seen how hard it can to get waste concrete up off a floor ,that probably dusty + smooth --not even a rough surface

[jack]

3 minutes ago, scottishjohn said:

how many months are you talking about between pours?

,you not going to top of last block anyway ,or polishing up the surface 

there will be plenty of grip between the layers -

not all poly systems are poured at one go either .

i suppose if you want to be belt and braces then drop some re-bar in 

you seen how hard it can to get waste concrete up off a floor ,that probably dusty + smooth --not even a rough surface

 

Do you know what ICF manufacturers say about this? I seem to recall it being important not to pour concrete on top of cured concrete in ICF, but that may have been in the context of basements and waterproofing.

[scottishjohn]

1 hour ago, Russell griffiths said:

if you had a 5m high wall and poured it in many pours it’s not exactly a monolithic structure is it. 

how many 5mm high walls are poured in one go with poly --the hydraulic pressure on the bottom would be mega

 bricks and mortar are not monolithic for that matter. they seem to stay up OK

you are  exagerating a nothing problem IMHO

the walls in uk on most ICf builds do not even have rebar vertically --just round frames and openings-not needed in our non earthquake country  for the load a normal  house 

 

[scottishjohn]

2 minutes ago, jack said:

 

Do you know what ICF manufacturers say about this? I seem to recall it being important not to pour concrete on top of cured concrete in ICF, but that may have been in the context of basements and waterproofing.

correct

 cured is 28days 

 I know both durisol +isotex and velox  etc have no problem with it

Edited May 28, 2019 by scottishjohn

[scottishjohn]

as usual  there has been thread creep 

if you got the money  then 1 pour is good -- up to 2.4m is what isotex says and maybe more if there are internal walls that join in to outside ones

 this suggestion of multiple pours or hand mixing was for someone who has sod all money but can take time to do it  at his own pace

 no problem  with UV ,like poly has and has to be rubbed off before rendering  or any sort of finish applied to it 

so woodcrete is very flexible for the extended builder and the way he wishes to do it

 

  

 

[K78]

6 hours ago, jamiehamy said:

Okay, clearly we're not going to agree on this or come close. 

 

For any icf'ers reading this thread I would suggest being very wary of building icf without bracing even if it's suggested. There are multiple reasons for this, from basic Health and Safety to implications for the subsequent concrete pours. Maybe 4 courses might with stand a strong wind but then you have two concrete pours not one. And how one keeps the walls plumb is beyond me - they are lightweight and have in many cases no inherent stiffness. And once you add in tons of concrete it's all magically to stay absolutely vertical? Each to their own of course. 

 

 

 

These blocks do require simple plywood bracing at the corners. 

 

The main selling point is speed. You can build to 2.4m high between pours. 

 

You dont pour 2.4m in one go. The idea is to keep to pump moving so you gradually build the height of the concrete up across the footprint of the house. If you just dumped to a 2.4 height in one go you would get a burst. 

[ToughButterCup]

20 minutes ago, scottishjohn said:

[...] I know ... Durisol ...[has]... no problem with it.

 

Hmmmmm. Not sure about that.

On my build, if I knew that there was to be a longish gap, I always built a lot of rebar into the original pour to key the next layer in.  Durisol do not make any statement about long gaps between pours.

 

I wholeheartedly agree with @jamiehamy's comments throughout this topic.

I have seen two separate whole walls (one internal, the other external) rocking to and fro (not on my build but at a pour to which I was invited) because an inexperienced pump-man had not fitted (or been directed to fit)  a 100mm restrictor in the final section of the 'snorkel' . The sheer volume of concrete falling (in that case just under 4 meters ) made the wall rock a good 100mm  left and right of the center line.  I did not stay to examine how much the variance there was in the final line of the wall.  The person supervising the pour was very experienced indeed. The owner was not present at the pour.

 

I pooped myself. There was no burst. I went home sweating :  two years later, although healing, the memory of our bursts is still very raw. 

 

[scottishjohn]

 

 

 

 

25 minutes ago, AnonymousBosch said:

I have seen two separate whole walls (one internal, the other external) rocking to and fro (not on my build but at a pour to which I was invited) because an inexperienced pump-man had not fitted (or been directed to fit)  a 100mm restrictor in the final section of the 'snorkel' . The sheer volume of concrete falling (in that case just under 4 meters ) made the wall rock a good 100mm  left and right of the center line.  I did not stay to examine how much the variance there was in the final line of the wall.  The person supervising the pour was very experienced indeed.

again what is very obvious from this statement is that the guide lines were not followed   and your comment about very experienced--sounds more like couldn,t give a crap  

a bunch of chancers by your description alone

durisol would not suggest a 4m high pour  --so not a product problem ,and you would need same snorkel attachment for a poly pour .

 

 

[ToughButterCup]

'... sounds more like...' and that's the thing we can't be sure. 

There's a lot of hubris in the ICF world, add to that poor practice - which in the case of ICF - you can sometimes get away with. 

[jamiehamy]

3 hours ago, K78 said:

 

These blocks do require simple plywood bracing at the corners. 

 

The main selling point is speed. You can build to 2.4m high between pours. 

 

You dont pour 2.4m in one go. The idea is to keep to pump moving so you gradually build the height of the concrete up across the footprint of the house. If you just dumped to a 2.4 height in one go you would get a burst. 

Agreed however were not talking about bursts, rather stability and safety during build and during pour. 

 

In short @scottishjohn is advocating building this type of icf without bracing, implying that experience makes this possible. Where we are we often get 30mph gusting 50mph winds when the wind comes from the east. Something to do with the warm air on the Moor gathering speed coming down the Glen. It happened on the day of our pour incidentally. 

 

It's careless and worrying to suggest something can be done a certain way without cautioning on the limitations, hence my question on windspeed. 

 

I'm confident that this particular product and many other icf products would not withstand a night of strong wind without either major damage or movement. That's not a criticism of any product either. And I'm certain that if it fell on you from the first storey just before pour, you'd get seriously injured. @AnonymousBosch will concur. 

 

Icf builders will weigh up the costs and risks when deciding on bracing. It didn't even enter my head to build our icf without bracing just to save a few hundred quid. 

 

 

 

[scottishjohn]

4 minutes ago, jamiehamy said:

Agreed however were not talking about bursts, rather stability and safety during build and during pour. 

 

In short @scottishjohn is advocating building this type of icf without bracing, implying that experience makes this possible. Where we are we often get 30mph gusting 50mph winds when the wind comes from the east. Something to do with the warm air on the Moor gathering speed coming down the Glen. It happened on the day of our pour incidentally. 

 

It's careless and worrying to suggest something can be done a certain way without cautioning on the limitations, hence my question on windspeed. 

 

I'm confident that this particular product and many other icf products would not withstand a night of strong wind without either major damage or movement. That's not a criticism of any product either. And I'm certain that if it fell on you from the first storey just before pour, you'd get seriously injured. @AnonymousBosch will concur. 

 

Icf builders will weigh up the costs and risks when deciding on bracing. It didn't even enter my head to build our icf without bracing just to save a few hundred quid. 

 

 

 

and what was the make of your ICF?

[Alexphd1]

Think Jamie used polarwall, quick question Jamie, did you use a poker with the polarwall?

[jamiehamy]

8 minutes ago, Alexphd1 said:

Think Jamie used polarwall, quick question Jamie, did you use a poker with the polarwall?

It was indeed. We didn't use a poker, we used a line pump with 10mm aggregate and an oversanded mix and advice was that is wasn't needed. The pump crew agreed as the mix was spot on and flowed very well. 

[Vijay]

13 minutes ago, jamiehamy said:

It was indeed. We didn't use a poker, we used a line pump with 10mm aggregate and an oversanded mix and advice was that is wasn't needed. The pump crew agreed as the mix was spot on and flowed very well. 

 

What's the oversanded mix? Not heard that mentioned before.  Did you not use a poker around any rebar/lintels, was told that has to be done?

[jamiehamy]

5 minutes ago, Vijay said:

 

What's the oversanded mix? Not heard that mentioned before.  Did you not use a poker around any rebar/lintels, was told that has to be done?

So, because we were using a 2inch line pump and pumping up to 40m, we needed a good flow. Oversanded mix helps along with the 10mm aggregate (it also by default has more cement too) . Because of this its a fairly wet mix and simply didn't need a poker. It flowed perfectly into all the corners. I did some samples after by taking off small bits of icf and the cores were perfect. But that was for ours, with 'normal' mixes then a poker may be needed. BTW, I owe you a drawing. I did one but it was wrong and not sat down to redo it yet @vijay 

[PeterW]

11 minutes ago, Vijay said:

What's the oversanded mix?

 

Oversanding is replacing some of the volume of aggregate with sand. So instead of a 1:3:3 cement:sand:aggregate, you would go 1:4:2 and it’s more fluid. 

 

Ad mix also makes it flow but it can affect strength. 

[Alexphd1]

@Conor just a idea.

What insulation spec of ICF are you looking at? If your going for a high insulation build maybe possible to use basic eps icf then add on another layer EWI as @Stones done with amvic icf. My quick calculation was this would have saved me a fair bit of £ doing this with nudara icf instead of buying a wide block and the extra 150mm inserts to beef the uvalues. Also a lot faster to put up ICF. 

I will investigate this further myself for next build, as they say every day is a school day! 

Edited May 28, 2019 by Alexphd1

[K78]

4 hours ago, jamiehamy said:

Agreed however were not talking about bursts, rather stability and safety during build and during pour. 

 

In short @scottishjohn is advocating building this type of icf without bracing, implying that experience makes this possible. Where we are we often get 30mph gusting 50mph winds when the wind comes from the east. Something to do with the warm air on the Moor gathering speed coming down the Glen. It happened on the day of our pour incidentally. 

 

It's careless and worrying to suggest something can be done a certain way without cautioning on the limitations, hence my question on windspeed. 

 

I'm confident that this particular product and many other icf products would not withstand a night of strong wind without either major damage or movement. That's not a criticism of any product either. And I'm certain that if it fell on you from the first storey just before pour, you'd get seriously injured. @AnonymousBosch will concur. 

 

Icf builders will weigh up the costs and risks when deciding on bracing. It didn't even enter my head to build our icf without bracing just to save a few hundred quid. 

 

 

 

Caution is definitely required. The block suppliers won’t put that you can go to 2.4m in writing. 

 

If I go this route the corners will be heavily braced. My site is sheltered so wind isn’t a huge concern. I wouldn’t attempt it on a site as exposed as yours. I’ll also be building in July. 

 

Im currently deciding between concrete block and isotex/durisol. I haven’t really looked at the eps ICF systems in detail. 

[Vijay]

8 hours ago, Alexphd1 said:

@Conor just a idea.

What insulation spec of ICF are you looking at? If your going for a high insulation build maybe possible to use basic eps icf then add on another layer EWI as @Stones done with amvic icf. My quick calculation was this would have saved me a fair bit of £ doing this with nudara icf instead of buying a wide block and the extra 150mm inserts to beef the uvalues. Also a lot faster to put up ICF. 

I will investigate this further myself for next build, as they say every day is a school day! 

 

exactly what I wish I did and also would have been much easier to cut than thick boards.

[Alexphd1]

Another idea.... say you add on extra 200mm EWI would it be possible to cut the ewi into a tight curve into the windows? i think this would be a nice detail!